U.S. patent application number 15/011547 was filed with the patent office on 2016-10-20 for dendrimer particles and related mixed matrix filtration membranes, compositions, methods, and systems.
The applicant listed for this patent is CALIFORNIA INSTITUTE OF TECHNOLOGY, KOREA ADVANCED INSTITUTE OF SCIENCE AND TECHNOLOGY. Invention is credited to Mamadou S. DIALLO, Madhusudhana Rao KOTTE, Alex KUVAREGA.
Application Number | 20160303517 15/011547 |
Document ID | / |
Family ID | 56544457 |
Filed Date | 2016-10-20 |
United States Patent
Application |
20160303517 |
Kind Code |
A1 |
DIALLO; Mamadou S. ; et
al. |
October 20, 2016 |
DENDRIMER PARTICLES AND RELATED MIXED MATRIX FILTRATION MEMBRANES,
COMPOSITIONS, METHODS, AND SYSTEMS
Abstract
Described herein are mixed matrix filtration membranes and
related, dendrimers, dendrimer particles, compositions, methods and
systems and in particular mixed matrix filtration membranes with an
embedded dendrimer particles and related compositions, methods, and
systems wherein each dendrimer particle comprises at least two
dendrimers each having at least two core chemical moieties having a
core multiplicity Nc; branch cell units attached to the core
chemical moiety or one to another, with the branch cell units
attached one to another having a branch cells multiplicity Nb; and
a number of surface functional groups Z presented on terminal
branch cell units, wherein Z=NcNb.sup.G with G.ltoreq.3.
Inventors: |
DIALLO; Mamadou S.;
(PASADENA, CA) ; KOTTE; Madhusudhana Rao;
(DAEJEON, KR) ; KUVAREGA; Alex; (DAEJEON,
KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CALIFORNIA INSTITUTE OF TECHNOLOGY
KOREA ADVANCED INSTITUTE OF SCIENCE AND TECHNOLOGY |
PASADENA
DAEJEON |
CA |
US
KR |
|
|
Family ID: |
56544457 |
Appl. No.: |
15/011547 |
Filed: |
January 30, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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62110319 |
Jan 30, 2015 |
|
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62164903 |
May 21, 2015 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B01D 67/0009 20130101;
B01D 71/60 20130101; B01D 67/0011 20130101; C02F 1/444 20130101;
B01D 2323/42 20130101; B01D 67/0006 20130101; B01D 71/34 20130101;
B01D 71/56 20130101; C02F 1/285 20130101; B01D 61/145 20130101;
B01D 2323/39 20130101; B01D 69/12 20130101; B01D 61/025 20130101;
B01D 2323/30 20130101; B01D 69/141 20130101; B01D 69/125 20130101;
C02F 2101/20 20130101 |
International
Class: |
B01D 69/14 20060101
B01D069/14; B01D 67/00 20060101 B01D067/00; C02F 1/28 20060101
C02F001/28; B01D 71/34 20060101 B01D071/34; B01D 71/60 20060101
B01D071/60; C02F 1/44 20060101 C02F001/44; B01D 61/14 20060101
B01D061/14; B01D 69/12 20060101 B01D069/12 |
Goverment Interests
STATEMENT OF GOVERNMENT GRANT
[0002] This invention was made with government support under Grant
No. CBET0948485 awarded by the National Science Foundation. The
government has certain rights in the invention.
Claims
1. A mixed matrix filtration membrane comprising: a plurality of
dendrimer particles embedded in a polymer matrix wherein each
dendrimer particle comprises at least two dendrimers each having at
least two core chemical moieties having a core multiplicity Nc;
branch cell units attached to the core chemical moiety or one to
another, with the branch cell units attached one to another having
a branch cells multiplicity Nb; and a number of surface functional
groups Z presented on terminal branch cell units, wherein
Z=NcNb.sup.G with G.ltoreq.3,
2. The mixed matrix filtration membrane of claim 1, comprising a
polymer of formula ##STR00049## wherein Q.sub.4, Q.sub.5 and
Q.sub.6 are independently a core, having a formula selected from:
##STR00050## wherein n.sub.2 is an integer from 1 to 18;
R.sub.35-R.sub.46 are independently a branch cell comprising a head
attachment atom and one to four tail attachment atoms joined to
form a chemical moiety wherein the head attachment atom and one to
four tail attachment atoms are linked by covalent bond, the branch
cell unit chemical moiety comprising amidoamine groups and/or ester
hydroxyl groups; FG1 and FG2 are terminal functional groups,
independently selected from amines, hydroxyl group, carboxylic
acids, azides, thiols, diacetylenyl, and acrylates; m.sub.5,
m.sub.6, or m.sub.7 are independently an integer selected from 1-4;
and l.sub.3 is equal to 2 m.sub.5; l.sub.4 is equal to 2 m.sub.6;
l.sub.5 is equal to 2 m.sub.7.
3. The mixed matrix filtration membrane of claim 1, wherein the
polymeric aggregate is formed by a polymer according to Formula
(I): ##STR00051## wherein: Q, Y, and Z comprise saturated aliphatic
hydrocarbon, aromatic hydrocarbon, or unsaturated aliphatic
hydrocarbons; m, l, and k independently are integers ranging
between 0-50; at least one of m, l, k is not equal to zero; j is an
integer ranging between 50-500; and at least one of Q (when
Q.noteq.0), Y (when Y.noteq.0), or Z (when Z.noteq.0), comprises
the polymer component functional group.
4. The mixed matrix filtration membrane of claim 3, wherein Q, Y,
and Z are independently selected from the group consisting of
Formulas II-XI: ##STR00052## wherein: n=0 or 1; m is an integer
ranging from 0-15; X is a functional group comprising an atom
selected from O, S, N, P, or F; and R.sub.1-R.sub.18 are
independently selected from: the polymer component functional
group; hydrogen; C.sub.1-C.sub.20 linear, branched, saturated,
unsaturated, or aryl hydrocarbon which are either substituted or
unsubstituted with O, N, B, S, P; or substituted O, N, B, S, or
P.
5. The mixed matrix filtration membrane of claim 1, wherein the
dendrimer particles embedded in the polymer matrix are in a
concentration of greater than 20 wt %.
6. The mixed matrix filtration membrane of claim 1, wherein the
dendrimer particles embedded in the polymer matrix are in a
concentration of greater than 40 wt %.
7. The mixed matrix filtration membrane of claim 1, wherein the
mixed matrix filtration membrane is a membrane absorber capable of
binding metal.
8. The mixed matrix filtration membrane of claim 1, wherein the
membrane absorber is capable of binding metal with a mean
percentage of bound metal of larger than 50%.
9. A method of making a mixed matrix filtration membrane with
embedded dendrimer-like particles, the method comprising: providing
a base polymer substantially soluble in a base polymer solvent;
providing a particle precursor having a portion substantially
soluble in the base polymer solvent and a portion substantially
insoluble in the base polymer solvent, the polymeric particle
precursor able to provide a dispersion of segregated domains in the
base polymer solvent, the polymeric particle precursor comprising
one dendrimer having one core chemical moiety with a core
multiplicity Nc, branch cell units attached to the core chemical
moiety or one to another, and a number of terminal functional
groups Z presented on terminal branch cell units, the number of
branch cell unit being attached one to another have a branch cells
multiplicity Nb, and the number of terminal functional groups Z
presented on terminal branch cell units, wherein Z=NcNb.sup.G with
G.ltoreq.3; mixing a base polymer with a polymer particle
precursor, and the base polymer solvent to provide a blend;
maintaining the blend for a time and under a condition to allow
crosslinking of at least some of the terminal functional groups Z
and in situ formation of dendrimer particles thus providing a dope
solution; and casting the dope solution to provide the mixed matrix
filtration membrane with embedded dendrimer particles.
10. The method of claim 9, wherein the maintaining comprises mixing
the blend with a crosslinker and/or an initiator capable of
reacting with the polymer particle precursor.
11. The method of claim 9, wherein the polymeric particle precursor
is a dendrimer having a general formula (XI): ##STR00053## wherein:
Q.sub.1 is a core, having a formula selected from: ##STR00054##
wherein n.sub.2 is an integer from 1 to 18 R.sub.19-R.sub.22 are
independently a branch cell unit comprising a head attachment atom
and one to four tail attachment atoms joined to form a chemical
moiety wherein the head attachment atom and one to four tail
attachment atoms are linked by covalent bond, such as
carbon-nitrogen bond of an amide, carbon-oxygen bond an ester,
carbon-carbon single or double bond; FG1 and FG2 are terminal
functional groups, independently selected from amines, hydroxyl
group, carboxylic acids, azides, thiols, diacetylenyl, and
acrylates. m.sub.2 is an integer ranging from 1-4; and l.sub.1 is
equal to 2m.sub.1.
12. The method of claim 9, wherein the polymeric particle
precursors comprise one or more polymeric particle precursor of
general formula (XV): ##STR00055## wherein: m.sub.3 is an integer
from 1 to 4; X.sup.1 is N; R.sub.23-R.sub.26 are independently
amidoamine groups; FG1 and FG2 are terminal groups, independently
selected from amines, hydroxyl group, carboxylic acids, azides,
thiols, diacetylenyl, and acrylates, and connected to each of the
R.sub.23, R.sub.24, R.sub.25 and R.sub.26; n.sub.3 is an integer
from 1 to 18 and l.sub.2 is equal to 2m.sub.3.
13. The method of claim 9, wherein the polymeric particle
precursors comprise G0, G1 and/or G2 PAMAM.
14. The method of claim 9, wherein the polymeric particle
precursors comprise G1 and/or G2 poly(propyleneimine) (PPI).
15. The method of claim 9, wherein the polymeric particle
precursors have a molecular weight less than 5000 daltons.
16. The method of claim 9, wherein the polymeric particle
precursors have a number of terminal groups less than 30.
17. The method of claim 9, wherein the polymeric particle
precursors are crosslinked to one another to form the dendrimer
particle.
18. A system for making a filtration membrane with in-situ
synthesized dendrimer particles, the system comprising a base
polymer for the membrane matrix substantially soluble in a base
polymer solvent, and polymeric particle precursors partially
soluble in the base polymer solvent the base polymer solvent, each
polymeric particle precursor being capable to form a dispersion of
segregated domains in the base polymer solvent, and comprising one
core chemical moiety having a core multiplicity Nc, branch cell
units attached to the core chemical moiety or one to another, and a
number of surface functional groups Z presented on terminal branch
cell units, wherein in each polymeric particle precursor the branch
cell units attached one to another having a branch cells
multiplicity Nb, and the number of surface functional groups Z
presented on terminal branch cell units, wherein Z=NcNb.sup.G with
G.ltoreq.3, and wherein the polymer particle precursor present
corresponding functional groups.
19. The system of claim 18, further comprising a crosslinker and/or
an initiator capable of reacting with the polymer particle
precursor.
20. The system of claim 18, further comprising the base polymer
solvent or a mixture of solvents compatible with the base polymer
solvent capable of dissolving the base polymer and/or a non-solvent
substantially incompatible with base polymer solvent or a mixture
of non-solvents substantially incompatible with the base polymer
solvent for the membrane polymer to promote phase separation and
subsequent membrane formation.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority to U.S. Provisional
Application No. 62/110,319, entitled "Mixed Matrix Membranes with
In Situ Synthesized Supramolecular Containers: Preparation,
Characterization and Applications to the Electrochemical Reduction
of CO2" filed on Jan. 30, 2015 with docket number CIT-7099-P and to
U.S. Provisional Application No. 62/164,903, entitled "Mixed Matrix
Membranes with In Situ Synthesized Supramolecular Containers:
Preparation, Characterization and Applications to the
Electrochemical Reduction of CO2" filed on May 21, 2015 with docket
number CIT-7099-P2, the disclosure of each of which is incorporated
by reference in its entirety. The present application is also
related to U.S. application Ser. No. 14/447,574 entitled "Mixed
Matrix Membranes with Embedded Polymeric Particles and Networks and
related Compositions, Methods, and Systems" filed on Jul. 30, 2014,
with Docket No. P1525-US which in turn claims priority to U.S.
Provisional Application No. 61/860,170, entitled "Mixed Matrix
Membranes with In-Situ Generated Polymeric Particles and Networks"
filed on Jul. 30, 2013 with docket number CIT-6634-P and to U.S.
Provisional Application No. 61/983,131, entitled "Mixed Matrix
Membranes with In-Situ Generated Polymeric Particles and Networks"
filed on Apr. 23, 2014 with docket number CIT-6634-P2, the
disclosure of each of which is incorporated by reference in its
entirety. The present application is also related to U.S.
application Ser. No. 13/754,883 entitled "Filtration Membranes and
Related Compositions, Methods and Systems" filed on Jan. 30, 2013
with Docket No. P1127-US which in turn claims priority to U.S.
Provisional Application No. 61/592,409, entitled "Ion-Selective
Nanofiltration Membranes Based on Polymeric Nanofibrous Scaffolds
and Separation Layers Consisting of Crosslinked Dendritic
Macromolecules" filed on Jan. 30, 2012 with docket number
CIT-5654-P4, to U.S. Provisional Application No. 61/601,410,
entitled "Low-Pressure Ion-Selective Membranes for Water Treatment
and Desalination: Synthesis, Characterization and Multiscale
Modeling" filed on Feb. 21, 2012 with docket number CIT-5654-P5, to
U.S. Provisional Application No. 61/711,021, entitled "Composite
and Multifunctional Polymeric Membranes with Embedded Polymeric
Micro/Nanoparticles: Compositions, Methods, Systems and
Applications" filed on Oct. 8, 2012 with docket number CIT-6334-P
and to PCT Patent Application PCT/US2012/050043 entitled
"Filtration Membranes, and Related Nano and/or Micro fibers,
Composites, Methods and Systems" filed on Aug. 8, 2012 with
attorney docket P1069-PCT which in turn claims priority to U.S.
Provisional Application No. 61/521,290, entitled "Low-Pressure
Ion-Selective Membranes for Water Treatment and Desalination:
Synthesis, Characterization and Multiscale Modeling" filed on Aug.
8, 2011 with docket number CIT-5654-P3, to U.S. Provisional
Application No. 61/592,409, entitled "Ion-Selective Nanofiltration
Membranes Based on Polymeric Nanofibrous Scaffolds and Separation
Layers Consisting of Crosslinked Dendritic Macromolecules" filed on
Jan. 30, 2012 with docket number CIT-5654-P4, and to U.S.
Provisional Application No. 61/601,410, entitled "Low-Pressure
Ion-Selective Membranes for Water Treatment and Desalination:
Synthesis, Characterization and Multiscale Modeling" filed on Feb.
21, 2012 with docket number CIT-5654-P5, each of the above
mentioned applications is incorporated herein by reference in its
entirety.
FIELD
[0003] The present disclosure relates to dendrimer particles and
related polymeric membranes and related compositions, methods and
systems. In particular the present disclosure relates to mixed
matrix membranes with embedded dendrimer particles and related
compositions, methods and systems.
BACKGROUND
[0004] Development of efficient membranes has been a challenge in
the field of energy generation and storage, fluid filtration, gas
separations, biopharmaceutical purifications in particular when
aimed at environmental and industrial separations.
[0005] Advances in industrial ecology, desalination and resource
recovery have established that industrial wastewater, seawater and
brines are important and largely untapped sources of critical
metals and elements. One of the challenges in metal recovery from
industrial wastewater is to design and synthesize high capacity,
recyclable and robust chelating ligands with tunable metal ion
selectivity that can be efficiently processed into low-energy
separation materials and modules.
[0006] Despite previous investigation and effort, development of
efficient, cost-effective and/or environmentally friendly polymeric
membranes and systems has been a challenge, in particular, the
development of high capacity chelating membranes to recover
metals.
SUMMARY
[0007] Provided herein are dendrimer particles, and related mixed
matrix filtration membranes compositions, methods, and systems that
which can have various applications such as industrial and
environmental separations.
[0008] According to a first aspect, a dendrimer particle is
described. The dendrimer particle comprises at least two dendrimers
each having a core chemical moiety having a core multiplicity Nc,
branch cell units attached to the at least two core chemical moiety
or attached one to another, and a number of surface functional
groups Z presented on terminal branch cell units. In each of the at
least two dendrimers in the dendrimer particle, the branch cell
units attached one to another have a branch cells multiplicity Nb,
and the number of surface functional groups Z presented on terminal
branch cell units, wherein Z=NcNb.sup.G with G.ltoreq.3. In some
embodiments, in the dendrimer particle, at least some of the branch
cell units are functionalized to present reactive sites, and in
particular reactive sites capable of binding a metal, such as
copper and/or platinum.
[0009] According to a second aspect, a mixed matrix filtration
membrane is described. The mixed matrix filtration membrane
comprises dendrimer particles herein described embedded in a
polymer matrix comprising a porous polymeric aggregate formed by a
base polymer.
[0010] According to a third aspect, a mixed matrix filtration
membrane is described. The mixed matrix filtration membrane
comprises dendrimer particles herein described in which at least
some of the of the branch cell units are functionalized to present
reactive sites, the dendrimer particles embedded in a polymer
matrix comprising a porous polymeric aggregate formed by a base
polymer. In some embodiments, in the dendrimer particle, at least
some of the functionalized branch cell units present reactive sites
capable of binding a metal, such as copper and/or platinum.
[0011] According to a fourth aspect, a method is described for
making a mixed matrix filtration membrane with in-situ generated
dendrimer particles herein described and mixed matrix filtration
membranes obtainable thereby. The method comprises: providing a
base polymer substantially soluble in a base polymer solvent;
providing particle precursors each having a portion substantially
soluble in the base polymer solvent and a portion substantially
insoluble in the base polymer solvent the polymeric particle
precursor able to provide a dispersion of segregated domains in the
base polymer solvent, the polymeric particle precursor comprising
one dendrimer having one core chemical moiety with a core
multiplicity Nc, branch cell units attached to the core chemical
moiety or one to another, and a number of terminal functional
groups Z presented on terminal branch cell units. In the polymeric
particle precursor, the number of branch cell units attached one to
another have a branch cells multiplicity Nb, and the number of
surface functional groups Z presented on terminal branch cell units
is Z=NcNb.sup.G with G.ltoreq.3. The method further comprises,
contacting the base polymer, the polymeric particle precursor, and
the base polymer solvent to provide a blend, and maintaining the
blend for a time and under a condition to allow crosslinking of at
least some of the terminal functional groups Z and in situ
formation of dendrimer particles herein described, thus providing a
dope solution. The method further comprises casting the dope
solution to provide a mixed matrix membrane with embedded dendrimer
particles herein described. In some embodiments the maintaining
comprises contacting the blend with a crosslinker and/or an
initiator capable of reacting with the polymer particle precursor
and in particular to the terminal functional groups Z. In some
embodiments, in the dendrimer particle precursor, at least some of
the branch cell units are functionalized to present reactive sites,
and in particular reactive sites capable of binding a metal such as
copper or platinum.
[0012] According to a fifth aspect, a system of making a filtration
membrane with in-situ synthesized dendrimer particles is described.
The system comprises a base polymer for the membrane matrix
substantially soluble in a base polymer solvent, and polymeric
particle precursors partially soluble in the base polymer solvent
the base polymer solvent, each polymeric particle precursor being
capable to form a dispersion of segregated domains in the base
polymer solvent, and comprising one core chemical moiety having a
core multiplicity Nc, branch cell units attached to the core
chemical moiety or one to another, and a number of surface
functional groups Z presented on terminal branch cell units. In the
polymeric particle precursor, the branch cell units attached one to
another have a branch cells multiplicity Nb, and the number of
surface functional groups Z presented on terminal branch cell
units, wherein Z=NcNb.sup.G with G.ltoreq.3. In some embodiments,
in the dendrimer particle precursor, at least some the branch cell
units are functionalized to present reactive sites, and in
particular reactive sites capable of binding a metal such as copper
or platinum. In some embodiments, the system also comprises a
crosslinker and/or an initiator capable of reacting with the
polymer particle precursor and/or the base polymer solvent or a
mixture of solvents compatible with the base polymer solvent
capable of dissolving the base polymer and/or a non-solvent
substantially incompatible with base polymer solvent or a mixture
of non-solvents substantially incompatible with the base polymer
solvent for the membrane polymer to promote phase separation and
subsequent membrane formation.
[0013] According to a sixth aspect, a nanofiber or microfiber is
described. The nanofiber or microfiber comprises a dendrimer
particle embedded in a polymeric component. In some embodiments the
nanofiber or microfiber comprises reactive sites, and the reactive
sites can be positively and/or negatively charged.
[0014] According to a seventh aspect, a method of making a nano
and/or micro fibers with embedded dendrimer particles is described,
the method comprising contacting a base polymer, a particle
precursor having a portion substantially soluble in the base
polymer solvent and a portion substantially insoluble in the base
polymer solvent the polymeric particle precursor herein described:
optionally a cross-linking component, and a solvent for a time and
under a condition to allow crosslinking of at least some surface
functional groups of the polymeric particle precursors thus
allowing the in situ formation of dendrimer particles herein
described to provide a dope solution; and spinning the dope
solution to provide a nanofiber or microfiber herein described. In
some embodiments, the polymeric component and dendritic component
are contacted to form a blend and the cross-linking agent is added
to the blend to allow in situ formation of the dendrimer particles
and obtain the dope. In some embodiments, in the dendrimer particle
precursor, the branch cell units are functionalized to present
reactive sites, and in particular reactive sites capable of binding
a metal such as copper or platinum
[0015] According to an eight aspect, a bicomposite membrane is
described, which comprises a plurality of nanofibers and/or
microfibers herein described attached to a polymer matrix formed by
a porous polymeric aggregate comprising dendrimer like particles.
In some embodiments, in the bicomposite membrane, the plurality of
nanofiber and/or microfiber are arranged in a mesh structure
forming a layer comprised in the membrane, alone or in combination
with additional layers. In some embodiments, the plurality of
nanofiber and/or microfibers are arranged in a substantially
parallel configuration, in particular in some of these embodiments,
one or more nanofibers and/or microfibers of the plurality of the
nanofibers and/or microfibers are hollow.
[0016] According to a ninth aspect, a method to filter a fluid is
described. The method comprises passing the fluid through one or
more mixed matrix membranes herein described. In some embodiments
the passing can be performed by pumping the fluid into the membrane
and extracting the pumped fluid from the mixed matrix
membranes.
[0017] According to a tenth aspect, a method to perform a reaction
catalyzed by one or more metals is described, the method comprises
contacting reagents to perform the reaction with one or more mixed
matrix membranes herein described in which the branch cell units of
dendrimer particles embedded in the polymeric aggregate are
functionalized to present reactive sites comprising the one or more
metals. In the method the contacting is performed for a time and
under condition to allow the reaction catalyzed by the one or more
metals. In some embodiments, the one or more metals comprise copper
and/or platinum.
[0018] Filtration membranes with embedded polymeric
micro/nanoparticles and related methods and systems herein
described are expected in several embodiments to be used to provide
a fast and scalable route for the preparation of a new generation
of high performance membranes,
[0019] Filtration membranes with embedded polymeric
micro/nanoparticles and related methods and systems herein
described are expected in several embodiments to provide a
versatile, flexible and/or tunable membrane platform to perform
selective chelating metals from a liquid and in particular of
industrial waste water or aqueous solutions,
[0020] Filtration membranes with embedded polymeric
micro/nanoparticles and related methods and systems herein
described are expected in several embodiments to provide modules
and systems at a low cost for a broad range applications including
waste water treatment, metal recovery, catalysis, gas separations,
chemical and biological purifications, and energy generation,
conversion and storage.
[0021] Filtration membranes with embedded polymeric
micro/nanoparticles and related methods and systems herein
described can be used in several embodiments, to produce high
capacity membrane absorbers for the selective extraction and
recovery of metals from aqueous solutions. In particular, these
mixed matrix filtration membranes can be used as membrane absorbers
or sorbents for the selective recovery of dissolved metals from
industrial liquid waste stream.
[0022] Filtration membranes with embedded polymeric
micro/nanoparticles and related methods and systems herein
described can be in several embodiments to provide
microenvironments formed by where reactions can occur. Mixed matrix
filtration membranes with embedded dendrimer micro/nanoparticles
and related methods and systems herein described can be used in
connection with applications wherein filtration is desired.
Exemplary applications comprise fluid filtration, gas separations,
biopharmaceutical purifications and energy generation and storage.
In particular, the mixed matrix membranes with embedded dendrimer
particles can be used in watered desalination. resource recovery
and additional applications associated with
industrial/environmental separations, including chemical and/or
biological purifications, which are identifiable by a skilled
person. More particularly, the mixed matrix membranes with embedded
dendrimer particles herein described can be used in applications
where selective absorption and inclusion or removal/conversion of
one more solutes/chemical compounds is desired.
[0023] The details of one or more embodiments of the disclosure are
set forth in the accompanying drawings and the description below.
Other features, objects, and advantages will be apparent from the
description and drawings, and from the claims.
BRIEF DESCRIPTION OF DRAWINGS
[0024] The accompanying drawings, which are incorporated into and
constitute a part of this specification, illustrate one or more
embodiments of the present disclosure and, together with the
detailed description and the examples, serve to explain the
principles and implementations of the disclosure.
[0025] FIG. 1 shows three major classes of branched macromolecules:
(I) Statistical (Random Hyperbranched), II (Semi-Controlled
(Dendrigrafts) and III Controlled (Dendrimers).
[0026] FIG. 2 shows an overview of synthetic strategies for (a)
branch cell construction, (b) Dendron construction and (c)
dendrimer construction.
[0027] FIG. 3 shows three-dimensional projection of dendrimer
core-shell architecture for G=4.5 poly (amidomine) (PAMAM)
dendrimer with principal architectural components (i) core, (ii)
interior and (iii) surface.
[0028] FIG. 4 shows in the upper panel the mathematical
relationship between the number of surface groups (Z), number of
branch cells (Ne), molecular weights (MW) of the dendrimers and the
generation of the dendrimers (G) and in the lower panel the
two-step reaction sequences involving alkylation chemistry and
amidation chemistry.
[0029] FIG. 5 illustrates a comparison of molecular shape change,
two-dimensional branch cell amplification surface branch cells,
surface groups (Z) and molecular weights (MW) as function of
generation: G=0-6.
[0030] FIG. 6 illustrates an exemplary method of Synthesis of PAMAM
dendrimers.
[0031] FIG. 7 illustrates congestion induced dendrimer shape
changes (I,II,III) with development of container properties (G=4, 5
and 6) for a family of PAMAM dendrimers.
[0032] FIG. 8 shows an exemplary method of synthesis of
dendrimer-encapsulated nanoparticles (DENS).
[0033] FIG. 9 illustrates chemical structures of low-generation
poly(amidoamine) (PAMAM) dendrimers (G0, G1 and G2) with terminal
NH.sub.2 groups.
[0034] FIG. 10 illustrates chemical structures of low-generation
PAMAM dendrimers (G1) with different core and terminal group
chemistry.
[0035] FIG. 11 illustrates chemical structures of low-generation
poly(propyleneimine) (PPI) dendrimers (G1 and G2) with terminal
NH.sub.2 groups.
[0036] FIG. 12 illustrates chemical structures of low-generation
2,2-bis(methylol)propionic acid (bis-MPA) dendrimers with various
terminal groups.
[0037] FIG. 13 illustrates chemical structures of low-generation 2
cyclotriphosphazene-phenoxymethyl(methylhydrazono) (PMMH) dendrimer
(G1) with various terminal groups.
[0038] FIG. 14 illustrates chemical structure of other
low-generation dendrimers of various core chemistry and terminal
groups.
[0039] FIG. 15 illustrates an exemplary embodiment of forming
dendrimer particles using EDC coupling.
[0040] FIG. 16 illustrates an exemplary embodiment of forming
dendrimer particles using click chemistry.
[0041] FIG. 17 illustrates an exemplary embodiment of forming
dendrimer particles using acrylate polymerization with an
initiator.
[0042] FIGS. 18A-C illustrate an exemplary embodiment of
preparation of mixed matrix membrane with in-situ synthesized
dendrimer-like particles. FIG. 18 A shows a schematic illustration
of the formation of dendrimer-like particles from G0 dendrimer;
FIG. 18 B shows a schematic illustration of mixed matrix membrane
preparation with embedded dendrimer-like particles: FIG. 18 C shows
a schematic illustration of the formation of dendrimer-like
particles from G1 dendrimer;
[0043] FIGS. 19 A-B show an exemplary embodiment of procedures and
reaction schemes used to prepare mixed matrix PVDF membranes with
in situ synthesized PAMAM particles. FIG. 19A highlights and
visualize the preparation procedures: (i) preparation of membrane
casting solution by dissolution of PVDF in TEP, (ii) addition of
PAMAM and ECH to the membrane casting solution to initiate the in
situ crosslinking reactions between PAMAM and ECH, (iii) membrane
preparation by phase inversion casting. FIG. 19B illustrates the
reaction schemes: (i) reaction of ECH epoxy groups with the primary
amino groups of the segregated PAMAM macromolecules in the dope
solution via ring opening nucleophilic substitution followed by the
nucleophilic displacement of the ECH chloro groups via reaction
with the remaining primary/secondary amino groups of the PAMAM
macromolecules.
[0044] FIG. 20 shows a picture of the crossflow ultrafiltration
(UF) system used in the water filtration and Cu(II) binding
measurements. The filtration cell (17.62 cm in length; 2.54 cm in
width and 0.3 cm in depth), pump head, reservoir and tubing were
built using Teflon and polyvinyl chloride to eliminate metal ion
sorption onto the system components.
[0045] FIG. 21 shows exemplary FESEM micrographs showing the
overall cross-sections of the neat PVDF membrane and mixed matrix
PVDF membranes with in situ synthesized PAMAM particles. Panels A
and B show neat PVDF membrane; Panels C and D show mixed matrix
MDP-G0 membrane; Panels E and F show mixed matrix MDP-G1 membrane.
The estimated composition of each membrane is listed in Table
8.
[0046] FIG. 22 shows representative magnified FESEM micrographs
(1000.times.) showing the presence of PAMAM particles at both the
surface layers and inside the matrices of the mixed matrix PVDF
membranes. Panel A: mixed matrix PVDF MDP-G0: Panel B: mixed matrix
PVDF MDP-G1. The estimated composition of each membrane is listed
in Table 7.
[0047] FIG. 23 shows representative FESEM surface micrographs
showing the top surfaces of mixed matrix PVDF membranes with in
situ synthesized PAMAM particles. Panels A and B: pristine PVDF
control membrane; Panels C and D: mixed matrix PVDF MDP-G0
membrane: Panels E and F: mixed matrix PVDF MDP-G1 membrane. The
estimated composition of each membrane is listed in Table 7.
[0048] FIG. 24 shows characterization of the mixed matrix MDP-G0
membrane by N.sub.2 adsorption permporometry. The pore diameters
were estimated using the Barrett-Joyner-Halenda (BJH) methodology
(4).
[0049] FIG. 25 shows characterization of the mixed matrix MDP-G1
membrane by N.sub.2 adsorption permporometry. The pore diameters
were estimated using the Barrett-Joyner-Halenda (BJH) methodology
(4).
[0050] FIG. 26 shows Characterization of the control PVDF membrane
by N.sub.2, adsorption permporometry. The pore diameters were
estimated using the Barrett-Joyner-Halenda (BJH) methodology
(4).
[0051] FIG. 27 shows DLS measurements of particle size distribution
for the mixed matrix MDP-G0 membrane with in situ synthesized
crosslinked PAMAM particles. The membrane was dissolved in TEP.
[0052] FIG. 28 shows DLS measurements of particle size distribution
for the mixed matrix MDP-G1 membrane with in situ synthesized PAMAM
particles. The membrane was dissolved in TEP.
[0053] FIG. 29 shows mid and near FTIR spectra of the neat PVDF
membrane and mixed matrix PVDF membranes with in situ synthesized
PAMAM particles. Panel A highlights the main absorption bands of
the mid IR region: (a) 3313 cm.sup.-1: --OH and --NH stretch from
amide, secondary amino or hydroxyl groups of PAMAM particles; (b)
1640 cm.sup.-1: --C.dbd.O stretch from amide groups of PAMAM
particles; (c) 1540 cm.sup.-1: --NH bending from the amide/amine
groups of PAMAM particles and (d) 1270 cm.sup.-1: --C--N stretch
from the amine groups of PAMAM particles. Panel B highlights the
main absorption bands of the near IR region: (e) 6850 cm.sup.-1:
--OH overtone from the ECH crosslinked PAMAM particles. (f) 5788
cm.sup.-1: overtones of --CH/--CH.sub.2 stretching from the ECH
crosslinked PAMAM particles and (g) 5116 cm.sup.-1: combination of
asymmetric OH stretching/bending from the ECH crosslinked PAMAM
particles. The estimated composition of each membrane is listed in
Table 8.
[0054] FIG. 30 shows XPS spectra of the control PVDF membrane and
mixed matrix PVDF membranes with in situ synthesized PAMAM
particles. The estimated composition of each membrane is listed in
Table 7.
[0055] FIG. 31 shows DIW flux of the mixed matrix MDP-G0 and MDP-G1
membranes as a function of filtration time at 2 bar. The estimated
composition of each membrane is listed in Table 7.
[0056] FIG. 32 shows permeate flux of aqueous solutions of Cu(II)
through the mixed matrix MDP-G0 and MDP-G1 membranes as a function
of solution pH and filtration time at 2 bar. The composition of
each membrane is listed in Table 8. A 2 L solution of Cu(II) [10
mg/L] at constant pH (3, 7 and 9) was pumped through each membrane
at 2 bar.
[0057] FIG. 33 shows extent of binding [mg of Cu(II) per mL of
membrane] and mean % Cu(II) bound in DIW by the mixed matrix PVDF
membranes with in situ synthesized PAMAM particles as a function of
filtration time and solution pH. The composition of each membrane
is listed in Table 8. A 2 L solution of Cu(II) [10 mg/L] at
constant pH (3, 7 and 9) was pumped through each membrane at 2
bar.
[0058] FIG. 34 shows representative FESEM micrographs illustrating
the surface and cross-sections of the bare and Cu(II) saturated
PAMAM-PVDF MDP-G0 membrane using different electron detectors. A 2
L solution of Cu(II) [10 mg/L] at pH 9 was pumped through the
membrane at 2 bar. Panel A shows a micrograph of the surface of the
bare MDP-G0 membrane using FESEM with a Through-the-lens Detector
(TLD): Panels B and C show micrographs of the Cu(II) MDP-G0
membranes using FESEM with TLD and Concentric Backscatter Detector
(CBS), respectively; Panel D shows a micrograph of the cross
section of the bare MDP-G0 membrane using FESEM with a
Everhart-Thomley Detector (ETD) and Panels E and F show the
micrographs of the Cu(II) MDP-G0 membranes using FESEM with TLD and
CBS.
[0059] FIG. 35 shows characterization of a Cu(II) laden MDP-G0
membrane by FT-Raman spectroscopy and XPS. The membrane composition
is listed in Table 8. A 2 L solution of Cu(II) [10 mg/L] at pH 9
was pumped through the membrane at 2 bar. Panel A shows the
FT-Raman spectra; Panel B shows the overall XPS scans while Panels
C and D highlight the C1s and O1s scans, respectively.
[0060] FIG. 36 shows XPS spectra of the Cu(II) loaded mixed matrix
PVDF MDP-G0-Cu.sup.2+ membrane with in situ synthesized PAMAM
particles. The estimated composition of each membrane is listed in
Table 7.
[0061] FIGS. 37A-B show Dendronized PAMAM bromoethylated
poly(2,6-dimethyl-1,4-phenylene oxide (BPPO) hollow fiber membranes
(HFMs) [7]. FIG. 37A shows a schematic illustration of membrane
preparation and FIG. 37B shows representative SEM images of a G3HFM
following immersion of a 50-mg sample in an aqueous solution (8 mL)
of Cu.sub.2(OH).sub.3Cl with a Cu(II) concentration of .about.12
mg/L at room temperature for 72 h. The SEM images show the
precipitation of Cu.sub.2(OH).sub.3Cl crystals on the surface of
the G3-NH.sub.2 dendronized PAMAM HFM. The SEM images of the Cu(II)
laden PAMAM HFM were acquired following sample free-drying using
field emission scanning electron microscopy (FESEM, SIRION 200
Series, FEI Corporation) at an acceleration voltage of 5 Kv.
[0062] FIG. 38 shows a schematic illustration of the postulated
mechanisms of Cu(II) complexation with the N and O donors of a
mixed matrix PVDF membrane with in situ synthesized crosslinked
PAMAM particles. Table 8 lists the estimated composition of each
membrane. The postulated mechanisms of Cu(II) complexation with the
N and O ligands of the membrane PAMAM particles were derived based
on the results of FT-Raman and XPS characterization a Cu(II)
saturated PVDF-PAMAM membrane absorber (FIG. 35) and published
literature on the mechanisms of Cu(II) binding to PAMAM dendrimers
in aqueous solutions.sup.27-30,38-40. Further independent
experiments and/or atomistic simulations need to be performed to
validate these hypothetical mechanisms.
[0063] FIG. 39 shows a schematic illustration of PVD membranes with
in-situ synthesized PAMAM dendrimer particles as containers for
Pt(0) nanoparticles using low-generation dendrimers (e.g. G0-NH2)
as particle precursors.
[0064] FIG. 40 shows an exemplary embodiment of the preparation of
a PVDF UF membrane (MDP-G1) with in-situ synthesized G1-NH.sub.2
PAMAM dendrimer particles for Pt(0) nanoparticles by reduction of
bound Pt.sup.4+ ions using sodium borohydride [NaBH.sub.4].
[0065] FIG. 41 shows Pt.sup.4+ loading onto a MDP-G1 membrane from
Flux measurements in one embodiment.
[0066] FIG. 42 shows Pt.sup.4+ loading onto a MDP-G1 membrane from
metal binding measurements in one embodiment.
[0067] FIG. 43 shows SEM micrographs of a Pt(0) loaded MDP-G1
membrane using a backscattered electron (BSE) detector in one
embodiment.
[0068] FIG. 44 shows SEM micrographs with spot EDX of a Pt(0)
loaded MDP-G1 membrane in one embodiment.
[0069] FIG. 45 shows Raman spectra of a MDP-G1 membrane loaded with
Pt.sup.4+ ions and Pt(O) nanoparticles in one embodiment.
[0070] FIG. 46 shows XPS spectra of a MDP-G1 membrane loaded Pt(0)
nanoparticles in one embodiment.
[0071] FIG. 47 shows TEM micrographs of PAMAM-G1 microparticles
from a Pt(0) loaded MDP-G1 membrane in one embodiment. For the TEM
experiments, a small piece of the reduced platinum loaded membrane
(Pt.sup.0/MDP-G1) was dissolved in 2 mL of triethyl phosphate (TEP)
by sonication for about 30 mins.
[0072] FIG. 48 shows TEM micrographs of Pt(0) nanoparticles from a
Pt(0) loaded MDP-G1 membrane in one embodiment.
[0073] FIG. 49 shows regioselective hydrogenation of selected
alkene and alkynes at room temperature using a Pt(0) loaded MDP-G1
membrane.
[0074] FIG. 50 shows recyclability of a Pt(0) loaded MDP-G1
membrane for the hydrogenation of cyclohexanone at room using
H.sub.2 (2 bar) in one embodiment.
[0075] FIG. 51 shows an exemplary embodiment of PVDF UF membrane
with in-situ synthesized PAMAM dendrimer particles as
supercontainers for Cu(0) nanoparticles using low-generation
dendrimers (e.g. G0-NH2) as particle precursors.
[0076] FIG. 52 shows SEM micrographs of a CU(0) loaded MDP-G0
membrane using a backscattered electron (BSE) detector in one
embodiment.
[0077] FIG. 53 shows Raman spectra of a MDP-G0 membrane loaded with
Cu.sup.2+ ions and Cu(0) nanoparticles in one embodiment.
[0078] FIG. 54 shows XPS spectra of a MDP-G0 membrane loaded with
Cu(0) nanoparticles in one embodiment.
[0079] FIG. 55 shows TEM micrographs of PAMAM-G0 microparticles
from a Cu(O) loaded MDP-G0 membrane in one embodiment. For the TEM
experiments, a small piece of the copper loaded membrane
(Cu.sup.0/MDP-G1) was dissolved in 2 mL of triethyl phosphate (TEP)
by sonication for about 30 mins.
[0080] FIG. 56 shows TEM micrographs of Cu(0) nanoparticles from a
Cu(0) loaded MDP-G0 membrane in one embodiment.
[0081] FIG. 57 shows examples of chelating agents that can be used
as ligand groups for the selective recovery of metal ions from
aqueous solutions. Panel A shows ligand chemistry and architecture
and Panel B shows Cu(II) coordination to selected monodentate,
bidentate, and macrocyclic ligands with nitrogen donors.
[0082] FIG. 58 shows a table with a list of physiocochemical
properties and binding affinities of selected metal ions to
selected monodentate ligands.
[0083] FIG. 59 illustrates introduction of one reactive site into
the dendritic component after a chemical transformation in step (a)
and the binding of a metal ion in step (b).
DETAILED DESCRIPTION
[0084] Provided herein are dendrimer particles and related mixed
matrix filtration membranes compositions, methods and systems that
allow in several embodiment to perform selective filtration of a
liquid and in particular of waste water for metal recovery.
[0085] The term "filtration" as used herein refers to the
mechanical or physical operation which can be used for separating
components of a homogeneous or heterogeneous solutions. Types of
filtration can be classified by the approximate sizes of chemicals
to be separated and can include particle filtration, or PF (>10
.mu.m); microfiltration, or MF (0.1-10 .mu.m); ultrafiltration, or
UF (0.01-0.1 .mu.m); nanofiltration, or NF (0.001-0.01 .mu.m); and
reverse osmosis, or RO (<0.001 .mu.m).
[0086] The term "chemicals" as used herein indicates a substance
with a distinct composition that is produced by or used in a
chemical process. Exemplary chemicals comprise particles,
molecules, metals, ions, organic compounds, inorganic compounds and
mixture thereof as well as any additional substance detectable
through chemical means identifiable by a skilled person. In
particular, in some embodiments, the chemicals can comprise solutes
dissolved in a fluid (e.g. water), and in particular dissolved
ions.
[0087] The term "membrane" as used herein refers to a porous
structure that is capable of separating components of a homogeneous
or heterogeneous fluid. In particular, "pores" in the sense of the
present disclosure indicate voids allowing fluid communication
between different sides of the structure. More particular in use
when a homogeneous or heterogeneous fluid is passed through the
membrane, some components of the fluid can pass through the pores
of the membrane into a "permeate stream", some components of the
fluid can be retained by the membrane and can thus accumulate in a
"retentate" and/or some components of the fluid can be rejected by
the membrane into a "rejection stream". Membranes can be of various
thicknesses, with homogeneous or heterogeneous structure. Membranes
can be comprised within, for example, flat sheets or bundles of
hollow fibers. Membranes can also be in various configurations,
including but not limited to spiral wound, tubular, hollow fiber,
and other configurations identifiable to a skilled person upon a
reading of the present disclosure (see, for example the web page
kochmembrane.com/Learning-Center/Configurations.aspx). Membrane can
also be classified according to their pore diameter. According to
IUPAC, there are three different types of pore size
classifications: microporous (dp<2 nm), mesoporous (2
nm<dp<50 nm) and macroporous (dp>50 nm). In particular, in
some instances, membranes can have pores with a 0.5 nm to 1.0 mm
diameters. Membranes can be neutral or charged, and particles
transport can be active or passive. The latter can be facilitated
by pressure, concentration, chemical or electrical gradients of the
membrane process.
[0088] In several embodiments, a filtration membrane herein
described comprises a polymer matrix formed by a porous polymeric
aggregate.
[0089] The term "polymer matrix" as used herein refers to
three-dimensional network of a polymer component of the membrane.
The term "polymer component" as used herein refers to one or more
linear polymers forming a polymeric aggregate of the polymer matrix
and comprising repeating structural unit forming long chains
without branches or cross-linked structures. In some instances
molecular chains of a linear polymer can be intertwined, but in
absence of modification or functionalization the forces holding the
polymer together are physical rather than chemical and thus can be
weakened by energy applied in the form of heat. In particular,
polymers forming the polymeric component in the sense of the
disclosure comprise substituted or unsubstituted aliphatic polymer,
a substituted or unsubstituted unsaturated polymer and a
substituted or unsubstituted aromatic polymer identifiable by a
skilled person upon reading of the present disclosure.
[0090] The term "polymer aggregate" or "polymeric aggregate" or
"aggregate" as used herein refers to aggregations of linear polymer
molecules that form an amorphous network structure. The amorphous
network structure can provide structural support to the filtration
membranes and pores through which desired substances can pass from
one side of the membrane to the other. Exemplary polymer aggregates
can be seen, for example, in FIG. 21, FIG. 22 and FIG. 34. In
particular, in some embodiments, the pores provided by the polymer
aggregate of the polymer matrix can permit the passage of some
molecules (e.g. solvent molecules such as water) while preventing
the passage of others (e.g. solute molecules such as proteins) thus
configuring the membrane to act as a size-exclusion membrane.
[0091] In embodiments herein described, the polymeric matrix
further includes dendrimer particles embedded in the polymer
matrix.
[0092] The term "dendrimers" used herein refer to repetitively
branched molecules having three basis architectural components
namely (i) a dendrimer core, (ii) repetitive branch cell units and
(iii) terminal functional groups. In particular, a "dendrimer core"
is a chemical moiety presenting a backbone and at least two anchor
atoms, each anchor atom defining a bonding position to a head
attachment atom of a branch cell unit. An exemplary illustration is
provided in FIGS. 9-13. In the dendrimer core, the backbone of the
dendrimer core can be any stable chemical moiety having the
capability to present anchoring positions for the attachment of
branch cell units. In particular, the core backbone structure can
be one of aromatic, heteroaromatic rings, aliphatic, or
heteroaliphatic rings or chains. In some embodiments, the backbone
of the dendrimer core can be one single atom, including C, N, O, S,
Si, or P. A "branch cell unit" is a chemical structure presenting
one head attachment atom and at least two tail attachment atoms.
The head attachment atom defines a bonding position to an anchor
atom of a dendrimer core or a tail attachment atom of another
branch cell unit. The tail attachment atom defines a bonding
position to a head attachment atom of another branch cell unit or
to a terminal functional group with the attachment possibly
performed directly or indirectly. A generation of branch cell units
within a dendrimer defines a shell of the dendrimer as will be
understood by a skilled person (see "Dendrimers and other Dendritic
polymers" by Jean M. J. Frechet and Donald A. Tomalia 2001 herein
incorporated by reference in its entirety) The branch cell units of
a generation typically define an interior space inside the
dendrimer herein also indicated as interior of shell as will be
understood by a skilled person. A "terminal functional group" of a
dendrimer, is a functional group presented on the outermost part of
the dendrimer attached to an end of a branch cell unit. The branch
cell units attaching the terminal functional groups typically
provide the outer shell or periphery of the dendrimer. The terms
"terminal functional groups" and "surface functional groups" are
herein used interchangeably.
[0093] Typically, in dendrimers in the sense of the disclosure, the
dendrimer core branch cell units and the terminal functional groups
can determine the physicochemical properties, as well as the
overall sizes, shapes, flexibility and/or container properties of
the dendrimers as the dendrimers are grown generation by
generation. An exemplary schematic illustration of dendrimer core,
branch cell units and terminal functional groups are illustrated in
FIGS. 1-3.
[0094] In dendrimers herein described, the core of the dendrimers
is typically the center from which size, shape, directionality and
multiplicity are expressed via the covalent connectivity to the
outer shells (see FIG. 3). One of the properties used to
characterize the dendrimer core is referred to as core
multiplicity, denoted by N.sub.c. N.sub.c represents the total
number of anchor atoms, and therefore the number of anchored
branches, on a dendrimer core. Examples of the dendrimer cores are
shown in FIGS. 10, 13 and 14. For example, PAMAM dendrimer core
shown in FIG. 10 has a N.sub.c value of four and 2
cyclotriphosphazene-phenoxymethyl(methylhydrazono) (PMMH) shown in
FIG. 13 has a N.sub.c value of six.
[0095] In dendrimers herein described, the branch cell units of
each shell define the type and amount of interior void space that
can be enclosed by the terminal groups as the dendrimer is grown
also known as interior of shell (see FIG. 3) One of the properties
used to characterize the branch cell units is referred to as branch
cell units multiplicity, denoted by N.sub.b. Branch cell units
multiplicity ("N.sub.b") represents a total number of tail
attachment atoms on each branch cell unit and determines the
density and degree of amplification as an exponential function of
the generation (G) as will be understood by a skilled person. In
the embodiment shown in FIGS. 9-11, the branch cell units
multiplicity ("N.sub.b") has a value of two. The interior
composition and amount of solvent filled void space determines the
extent and nature of guest-host (endo-receptor) properties that are
associated with a particular dendrimer family and generation. In
some embodiments, the solvent filled interior void space can
exhibit encapsulation properties that can be amenable to organic,
inorganic or metal compounds.
[0096] In dendrimers herein described, the surface of the
dendrimers consists of reactive or passive terminal groups that can
perform several functions (see FIG. 3). With appropriate function,
the terminal groups can serve as a template polymerization region
as each generation is amplified and covalently attached to the
precursor generation. Additionally, the surface groups can function
as passive or reactive gates controlling control entry or departure
of guest molecules from the dendrimer interior. Example of the
terminal groups can be found, for example, in FIG. 10 and FIG. 12,
as well as others that can be readily identified by a person
skilled in the art.
[0097] The configuration of the number of surface functional
groups, the number of branch cells, the molecular weights and the
number of generation of dendrimers can be expressed by mathematical
equation as shown in FIG. 4. In particular, both the core
multiplicity (Nc) and branch cell units multiplicity (Nb) determine
the precise number of terminal groups (Z) and mass amplification as
a function of generation (G). Such relationship can be represented
using the mathematical formula below:
Z=N.sub.cN.sub.b.sup.G
[0098] In particular the parameter G indicates the generation
number of the dendrimer as will be understood by a skilled person
as dendrimers are typically classified by generation number. The
common notation for this classification is GX followed by the name
of the dendrimer, where X is a number referring to the generation
number. A zero generation dendrimer is annotated as G0 followed by
the name of the dendrimer; a first generation dendrimer is
annotated as G1 followed by the name of the dendrimer and so on.
For example, the zero generation PAMAM dendrimer is annotated as G0
PAMAM, the first generation PAMAM dendrimer is annotated as G1
PAMAM, the second generation PAMAM dendrimer is annotated as G2
PAMAM and so on.
[0099] The term "low-generation dendrimer" herein described refers
to any one of a G0 to G3 dendrimer and "high-generation dendrimer"
herein described refers to any one of G4 dendrimers or a higher
generation dendrimer.
[0100] The dendrimer generation is provided as a result of an
iterative manufacturing process by which dendrimers are "grown" off
a central core, wherein in each iteration branch cell units are
attached to the core of the dendrimer or to terminal branch cell
units of the dendrimer. Accordingly, in the iterative manufacturing
processes each iteration provides a generation of branch cell units
defining a new shell of the dendrimer as well as a new "generation"
of the dendrimer. The term "terminal branch cell units" indicates
branch cell units presenting functionalized or unfunctionalized
tails on the outermost part of the dendrimers and forming the outer
shell of the dendrimer. In some embodiments, dendrimers can be
synthesized by divergent methods. Divergent synthesis refers to the
sequential "growth" of a dendrimer layer by layer, starting with a
core moiety which contains functional groups capable of acting as
active sites in the initial reaction. Each round of reactions in
the series forms a new generation of dendrimers with exponentially
increased number of available surface groups. In other embodiments,
dendrimers can also be synthesized by convergent methods as will be
understood by a person of ordinary skill in the art. Detailed
information about the dendrimer synthesis methods can be found in
related publications and textbooks such as "Dendrimers and other
Dendritic polymers" by Jean M. J Frechet and Donald A. Tomalia 2001
herein incorporated by reference in its entirety.
[0101] The dendrimer diameters usually increase linearly as a
function of shells or generations added, whereas, the terminal
functional groups increase exponentially as a function of
generation. Lower generations generally have open, floppy
structures, whereas higher generations become robust, less
deformable spheroids, ellipsoids or cylinders depending on the
shape and directionality of the core.
[0102] Higher generation dendrimers also have a high degree of
branching and more exposed functional groups on the surface, which
can later be used to customize the dendrimer for a given
application. For example, highly branched dendrimers typically
indicate a macromolecule whose structure is characterized by a high
degree of branching that originates from a central core region.
Exemplary highly branched dendritic macromolecules comprise
dendrimers, hyperbranched polymers, dendrigraft polymers,
dendronized linear polymers, tecto-dendrimers, core-shell (tecto)
dendrimers, hybrid linear dendritic copolymers, dendronized
polymers and additional molecule identifiable by a skilled person
(see e.g. US 2006/0021938, US 2008/0185341, US 2009/0001802. US
2010/0181257, US 2011/0315636, and US 2012/0035332 each
incorporated by reference in its entirety, also describing method
of making highly branched dendritic macromolecules). Exemplary
dendritic nanomaterials can include, for example, any highly
branched dendritic macromolecules or mixtures thereof, in
dendrimer-based supramolecular assemblies, 3-D globular
nanoparticles or dendritic nano/microparticles identifiable by a
skilled person (see, for example, US 2006/0021938, US 2008/0185341,
US 2009/0001802, US 2010/0181257, US 2011/0315636, and US
2012/0035332 each incorporated by reference in its entirety).
[0103] Highly branched dendrimers typically comprise dendrimer of
generation G4 or higher. Low generation dendrimers typically
comprise dendrimer of generation G3 or lower.
[0104] An exemplification of dendrimer generations is provided
below with reference to the exemplary dendrimer PAMAM. A skilled
person will understand the applicability to other dendrimer and
dendrimer like particles upon reading of the present
disclosure.
[0105] In some embodiments, the dendrimers used as building blocks
for the formation of dendrimer particles are polyamidoamine (PAMAM)
dendrimers. In those embodiments, examples of low generation
dendrimers include G0-G3 PAMAM and examples of high generation
dendrimer include G4-G6 PAMAM.
[0106] Polyamidoamine (PAMAM) dendrimers are hyperbranched polymers
with unparalleled molecular uniformity, narrow molecular weight
distribution, defined size and shape characteristics and a
multifunctional terminal surface. PAMAM dendrimers consist of an
ethylenediamine core, a repetitive branching amidoamine internal
structure and a primary amine terminal surface. Similar to other
dendrimers, PAMAMs have a tree-like branching structure with each
outward layer containing exponentially more branching points.
[0107] In some embodiments, PAMAM dendrimers can be synthesized by
the divergent approach that involves the in situ branch cell
construction in stepwise, iterative stages (generation=0, 1, 2, 3 .
. . ) around a desired core to produce mathematically defined
core-shell structures as illustrated in FIG. 2. Typically,
ethylenediamine (N.sub.c=4) or ammonia (N.sub.c=3) are used as
cores and allowed to undergo reiterative two-step reaction
sequences involving: (a) exhaustive alkylation of primary amines by
Michael addition with methyl acrylate, and (b) amidation of
amplified ester groups with a large excess of ethylenediamine to
produce primary amine terminal groups as illustrated in FIG. 3.
N.sub.c refers to the number of arms (i.e. dendrons) anchored to
the core.
[0108] As shown in FIG. 2 and FIG. 6, the first reaction sequence
on the exposed dendron creates G=0 (core branch cell). One
iteration of the alkylation/amidation sequence produces an
amplification of terminal groups from 1 to 2 with the in situ
creation of a branch cell at the anchoring site of the dendron that
constitutes G=1. Repeating these iterative sequences, produces
additional shells (generations) of branch cell units that amplify
mass and terminal groups according to the mathematical expressions
described in FIG. 4.
[0109] Predicted molecular weights can be confirmed by mass
spectroscopy and other analytical methods as will be known to a
person skilled in the art. Predicted numbers of branch cells,
terminal groups (Z) and molecular weights (MW) as a function of
generation for ammonia core (Nc=3) PAMAM dendrimers are described
in FIG. 5. The molecular weights approximately double as one
progresses from one generation to the next. The surface groups (Z)
and branch cells (BC) amplify mathematically according to a power
function, thus producing discrete, monodispersed structures with
precise molecular weights as described in FIG. 5. These predicted
values can be verified by mass spectroscopy for the earlier
generations. With divergently synthesized dendrimers, minor mass
defects can be observed for higher generations as
congestion-induced de Gennes dense packing begins to take
effect.
[0110] Calculated properties such as molecular weight, measured
diameter and number of surface groups for PAMAM can be found in
Table 1.
TABLE-US-00001 Generation Molar Mass Number of Hydrodynamic (G)
(Daltons) Terminal Groups Diameter (nm) 0 517 4 1.5 1 1,430 8 2.2 2
3,256 16 2.9 3 6,909 32 3.6 4 14,214 64 4.5 5 28,826 128 5.4 6
58,048 256 6.7 7 116,493 512 8.1 8 233,383 1024 9.7 9 467,162 2048
11.4 10 934,720 4096 13.5
[0111] Dendrimers, in particular, higher generation dendrimers can
serve as supramolecular containers for cations, anions, organic
solutes and bioactive molecules depending on dendrimer
generation.[1]
[0112] FIG. 7 shows congestion induced dendrimer shape changes
(I,II,III) with development of container properties (G=4, 5 and 6)
for a family of PAMAM dendrimers. The PAMAM dendrimers can be
utilized as templates for the preparation of dendrimer-encapsulated
nanoparticles (DENs) (see FIG. 8) with tunable electronic, optical
and catalytic properties. [1]
[0113] FIG. 8 illustrates the synthesis of dendrimer-encapsulated
nanoparticles (DENS). These higher generation PAMAM dendrimers
(e.g. G4-G6 NH.sub.2) are expected to be used as (i) high capacity,
selective and selective supramolecular containers for metal ions
(e.g. Cu(II), Pt(II), Pd(II), Ag(I), Au(I) and U(VI)) and (ii)
templates for the preparation of redox and catalytic DENs [Cu(0),
Pt(0) and Pd(0)].
[0114] In embodiments herein described low generation dendrimers
can be used as building blocks to provide dendrimer particles which
have properties comparable with the ones of the more expensive
higher generation dendrimers.
[0115] The term "dendrimer particles" described herein refer to
particles of covalently linked and in particular cross-linked
polymeric molecules with low degree of branching in which the
covalently linked or cross-linked polymeric molecules form
aggregate nanostructures and/or microstructure possessing a high
degree of branching and a controlled composition, architecture,
and/or size. Polymeric molecules with low degree of branching that
can form polymeric particle comprise low-generation dendrimer, for
example, low-generation PAMAM, PPI, 2,2-bis(methylol)propionic acid
(MPA).
[0116] Accordingly in embodiments herein described polymeric
molecules with low degree of branching and in particular low
generation dendrimers can be used as polymeric particle precursors
in the formation of the dendrimer particles herein described.
[0117] The term "polymeric particle precursor" described herein
refer to a chemical compound that can covalently link another same
or different chemical compound, through a cross-linking agent or
reactive surface functional group to produce a third compound with
resulting increased covalent bonds formed.
[0118] In embodiments herein described, the low-generation
dendrimers covalently link one to another through their respective
surface functional groups In particular, a low-generation
dendrimers forming a polymeric particle precursor comprises one
core chemical moiety having a core multiplicity Nc, branch cell
units attached to the core chemical moiety or one to another, and a
number of surface functional groups Z presented on terminal branch
cell units. In the polymeric particle precursor, the number of
branch cell unit attached one to another have a branch cells
multiplicity Nb, and the number of surface functional groups Z
presented on terminal branch cell units, wherein Z=NcNb.sup.G with
G.ltoreq.3. In the method, the polymeric particle precursors can
present functional groups that can crosslink with corresponding
functional groups from other polymeric particle precursors either
directly or indirectly.
[0119] The term "functional group" as used herein indicates
specific groups of atoms within a molecular structure that are
responsible for the characteristic chemical reactions of that
structure. Exemplary functional groups include hydrocarbons, groups
containing halogen, groups containing oxygen, groups containing
nitrogen and groups containing phosphorus and sulfur all
identifiable by a skilled person. In particular, functional groups
in the sense of the present disclosure include a carboxylic acid,
amine, triarylphosphine, azide, acetylene, sulfonyl azide, thio
acid and aldehyde. In particular, for example, the first functional
group and the second functional group can be selected to comprise
the following binding partners: carboxylic acid group and amine
group, azide and acetylene groups, azide and triarylphosphine
group, sulfonyl azide and thio acid, and aldehyde and primary
amine. Additional functional groups can be identified by a skilled
person upon reading of the present disclosure.
[0120] As used herein, the term "corresponding functional group"
refers to a functional group that can react with another functional
group under appropriate conditions. Thus, functional groups that
can react one with the other can be referred to as corresponding
functional groups. Typically, a reaction between one functional
group and its corresponding functional results in binding together
of the two molecular structures presenting these two functional
groups.
[0121] In embodiments where the corresponding functional groups are
in the dendrimer forming a first polymeric particle precursor and
in the dendrimer forming a second polymeric particle precursor, the
corresponding functional groups react to form a covalent bond thus
attaching the first polymeric particle precursor and the second
polymeric particle precursor as will be understood by a skilled
person upon reading of the present disclosure.
[0122] The term "attach" or "attachment" as used herein, refers to
connecting or uniting by a bond, link, force or tie in order to
keep two or more components together, which encompasses either
direct or indirect attachment such that, for example, a first
compound is directly bound to a second compound or material, and
the embodiments wherein one or more intermediate compounds, and in
particular molecules, are disposed between the first compound and
the second compound or material. In particular, in some
embodiments, the polymeric nanomaterial can be associated with the
polymer matrix by, for example, by being physically embedded in the
polymer matrix, by being covalently bonded to the polymeric
component, or through a combination of both. In some embodiment,
the functional groups as used herein refer to specific groups of
atoms within a molecular structure such as a dendrimer or specific
groups of atoms that can attached to the molecular structure of the
dendrimer, which are responsible for a characteristic chemical
reaction between one functional group and its corresponding
functional group. Exemplary functional groups include groups
containing double or triple bonds, groups containing halogen,
groups containing unsaturated hydrocarbon group, oxygen, groups
containing nitrogen and groups containing phosphorus and sulfur all
identifiable by a skilled person.
[0123] In some embodiments herein described, the functional groups
presented in one dendrimer can crosslink with a corresponding
functional group of another dendrimer directly to form a covalent
bond thus linking the one dendrimer with the another dendrimer.
Alternatively, the functional groups presented in one dendrimer can
crosslink with its corresponding functional group from another
dendrimer indirectly through a crosslinking agent.
[0124] The term "crosslinking" herein used generally refer to a
direct or indirect linking of two separate polymers. Crosslinking
can occur through chemical reactions by addition of a crosslinking
agent or through chemical reactions that are initiated by heat,
pressure, change in pH, radiation or a free radical initiator that
are commonly referred to as "initiator" as will be understood by a
person skilled in the art.
[0125] In some embodiments, corresponding functional groups can
react in absence of an initiator. Exemplary, corresponding
functional groups which can react in absence of an initiator are
functional groups comprising one double and/or triple bond such as
an unsaturated hydrocarbon group, a group containing oxygen, a
group containing nitrogen and a group containing phosphorus and/or
sulfur, and more particularly diacetylene groups, methacrylate
groups, acryloyl groups, sorbyl ester groups, diene groups, styrene
groups vinyl groups and isocyano groups. Additional functional
groups that can react in absence of an initiator can be identified
by a skilled person upon reading of the present disclosure.
[0126] In some embodiments, corresponding functional groups can
react in presence of an initiator. Exemplary functional groups
capable of reacting in presence of an initiator to provide
crosslinked dendrimer are diacetylene groups (initiator-UV
exposure), methacrylate groups (initiator-UV exposure,
azobisisobutyronitrile (AIBN)+heat), acryloyl groups
(initiator-(AIBN)+heat), sorbyl ester groups (initiator-UV
exposure, azobisisobutvronitrile (AIBN)+heat), diene groups
(initiator-UV exposure, azobisisobutyronitrile (AIBN)+heat,
azobis(2-amidinopropane) dihydrochloride (AAPD)+heat), styrene
groups (initiator-UV exposure), vinyl groups (initiator-UV
exposure) and isocyano groups (initiator-UV exposure). In some
embodiments, in a crosslinkable dendrimer herein described at least
one functional group is selected from diacetylenyl, acryloyl,
methacryloyl and dienyl groups.
[0127] In some embodiments, a functional group of one dendrimer can
be directly cross-linked to a corresponding functional group of
another dendrimer and the functional group and the corresponding
functional group can have different chemical structures. In one
example, the functional group on one dendrimer comprises an alkynyl
group and its corresponding functional group from another dendrimer
comprises azide. At the presence of a copper(I) catalyst, azide
reacts with the alkynyl group to form
1,4-disubstituted-1,2,3-triazole, resulting in the crosslinking of
the two dendrimers Other functional groups that identifiable by a
person of skill in the art, including those of Diels Alder
reactions.
[0128] In some embodiments, the polymeric particle precursor used
as building blocks for the formation of dendrimer particles are low
generation dendrimers In some embodiments, the low-generation
dendrimers are low-generation Polyamidoamine (PAMAM) dendrimers
such as G0, G1, G2 or G3 PAMAM, in particular, low generation
Polyamidoamine (PAMAM) dendrimers with terminal NH.sub.2 groups as
shown in FIG. 9.
[0129] In some embodiments, the terminal groups of the low
generation PAMAM dendrimers can be amine, amidoethanol, succinamic
acid, sodium carboxylate, tris(hydroxymethyl) amidomethane,
carbomethoxy-pyrrolidinone, amidoethylethanolamine, polyethylene
glycol as shown in FIG. 10 and others that can be readily
identified by a person skilled in the art.
[0130] In some embodiments, the dendrimers used as building blocks
for the formation of dendrimer particles are low generation
poly(propyleneimine) (PPI] dendrimers such as G1 or G2 PPI with
terminal NH.sub.2 groups (see FIG. 1). This family of dendrimers is
commercially available from SyMO-Chem
(http://www.symo-chem.nl/dendrimer.htm).
[0131] In some embodiments, the dendrimers used as building blocks
for the formation of dendrimer particles are low generation
2,2-bis(methylol)propionic acid (bis-MPA) dendrimers with various
terminal groups (see FIG. 12). This family of dendrimers is
commercially available from Polymer Factory (see web page
http://www.polymerfactory.com/dendrimers at the filing date of the
present disclosure).
[0132] In some embodiments, the dendrimers used as building blocks
for the formation of dendrimer particles are low generation 2
cyclotriphosphazene-phenoxymethyl(methylhydrazono) (PMMH) dendrimer
(G1) with various terminal groups (see FIG. 13). This family of
dendrimers is commercially available from Biodendrimers
International (http://www.biodendrimers.com/products/).
[0133] In some embodiments, the dendrimers that can be used as
building blocks for the formation of dendrimer particles include
low-generation dendrimers of various core chemistry and terminal
groups are shown in FIG. 14 as well as others that can be readily
identified by a person skilled in the art.
[0134] In some embodiments, the polymeric molecules forming the
dendrimer particle precursor can include branched polymers such as
low-generation dendrimers, for example, low generation
poly(amidoamine) (PAMAM) (see, for example, Example 5).
[0135] In some embodiments, the low-generation dendrimers used as
the building blocks to form dendrimer particles have a molecular
weight less than 5000 daltons.
[0136] In some embodiments, the low-generation dendrimers used as
the building blocks to form dendrimer particles have a number of
terminal groups less than 30.
[0137] In some embodiments, the low-generation dendrimers used as
the building blocks to form dendrimer particles have a hydrodynamic
diameter less than 5 nm.
[0138] The dendrimer particles formed by the covalent linking of
polymeric particle precursors herein described comprises at least
two core chemical moieties having a core multiplicity Nc, branch
cell units attached to the at least two core chemical moiety or
attached one to another, and a number of surface functional groups
Z presented on terminal branch cell units. In the dendrimer
particles, the branch cell units attached one to another have a
branch cells multiplicity Nb, and the number of surface functional
groups Z presented on terminal branch cell units, wherein
Z=NcNb.sup.G with G.ltoreq.3.
[0139] In particular, in dendrimer particles herein described at
least some of the interior of shells of the dendrimers forming the
dendrimer particles exhibit encapsulation properties that can be
used to encapsulate organic, inorganic or metal compounds
[0140] In mixed membrane herein described the dendrimer particles
are embedded in a polymer matrix alone or in combination with other
particles.
[0141] The term "embed" or "embedded" as used herein refers to a
spatial relationship of an item relative to a structure in which
the item is at least partially enclosed within the structure. In
particular, when used in connection to spatial relationship of
nanoparticle with reference to a polymer matrix the term "embed"
refers to the nanoparticles being at least partially enclosed by
the matrix in a suitable configuration within the polymeric
aggregate. In particular, in dendrimer particles herein described
embedded in a polymer matrix corresponding functional groups in the
polymer forming the polymer matrix and in the polymer forming the
nanoparticle typically react to form a covalent bond, a hydrogen
bond or other bond functional to the attachment of the polymer
forming the polymer matrix and the polymer forming the nanoparticle
identifiable by a skilled person upon reading of the present
disclosure.
[0142] In some embodiments the nanoparticles can be attached (e.g.
through covalent bonds or through non-covalent interactions such
as, for example, van Der Waals forces) to the polymer molecules
forming the porous aggregate in particular in correspondence to
pores of the porous aggregate structure of the polymer matrix (see
e.g. FIG. 21. FIG. 22 and FIG. 34).
[0143] In embodiments herein described, at least one polymer of the
polymers forming the polymer component of the polymer matrix has a
functional group capable of interacting with a corresponding
functional group on the dendrimer particles.
[0144] In some embodiments herein described, the polymer matrix
with embedded dendrimer particles can behave similarly as those
formed by high-generation dendrimers in various filtration purposes
and particularly serve as multifunctional membranes for a variety
of SusChEM related applications, including water treatment, metal
extraction and recovery, (biochemical separations and purifications
and catalysis and reaction engineering, with similar or even
improved properties and performance including higher
permselectivity and flux, greater mechanical strength and lower
fouling propensity.
[0145] The membrane absorbers can be utilized as templates for
preparation of dendrimer-encapsulated nanoparticles (DENs) with
tunable electronic, optical and catalytic properties. The membrane
absorbers described herein with in-situ synthesized dendrimer
particles can also serve as multifunctional membranes for a variety
of SusChEM related applications
[0146] In some particular embodiments, the polymeric matrix with
embedded dendrimer particles can serve as supercontainers. The term
"supercontainers" herein used refer to polymeric material
exhibiting encapsulation properties for retaining target compounds
including cations, anions, organic solutes, bioactive molecules and
catalytic and redox active metallic/bimetallic nanoparticles and
cluster.
[0147] In the embodiments shown in FIGS. 18A-C, the supercontainer
formed by G0 dendrimer particles and G1 dendrimer particles have a
hard shell formed by crosslinking primary amine groups of the G0 or
G1 dendrimer and a soft core of G0 or G1 dendrimers crosslinked to
the shell.
[0148] In some embodiments, target compounds to be contained in the
supercontainers can form complex with the dendrimers in the soft
core depending on the identity of the target compounds and the
chemical reaction between the target compounds and the branch cell
units of the dendrimer. For example, the N and O donors of the
dendrimer particles as well as water molecules and/or counterions
trapped inside the dendrimer particles can chemically coordinate
with metals in order to contain the metals in the supercontainers
(see Examples 7-9 and FIGS. 38-39)
[0149] In some embodiments, the supercontainers can be
functionalized with ligand groups further presenting a reactive
site that can selectively bind and contain specific target
compounds, such as metal ions (see FIG. 59).
[0150] In some embodiments, the metal ion can form complexation
with selected ligand groups based on a ligand exchange reaction. In
some particular embodiments, metal ion complexation is an acid-base
reaction that depends on several parameters including (i) ion size
and acidity, (ii) ligand basicity and molecular architecture and
(iii) solution physical-chemical conditions. FIG. 57 shows a broad
range of ligand groups with different chemistry and architectures
including (i) unidentate ligands, (ii) chelating ligands, (iii)
macrocycles, (iv) cryptands and (v) dendrimers.
[0151] As a person skilled in the art will understand, the Hard and
Soft Acids and Bases (HSAB) principle provides a general guidance
for selecting an effective ligand (i.e. Lewis base) for a given
metal ion (i.e. Lewis acid). [3-6] The table shown in FIG. 58 lists
the physicochemical properties of selected metal ions present in
seawater along with their binding constants to selected unidentate
ligands in aqueous solution. [3-6] The OH.sup.- ligand is
representative of ligands with negatively charged "hard" O donors
such as oxalate and catecholate (FIG. 57). Conversely, NH.sub.3 and
imidazole (FIG. 57) are representative of ligands with saturated
hard N donors (e.g. ammonia and ethylene diamine (EDA)) and
unsaturated N donors, respectively. In contrast, the
mercaptoethanol group (HOCH.sub.2CH.sub.2S') (FIG. 57) is
representative of ligands with soft donors (e.g. thiols).
[0152] The table in FIG. 58 lists the stability constants of
selected metal ions in aqueous solution to selected unidentate
ligands. The stability constant (log K.sub.1) is one the most
widely utilized indicator of the binding affinity of a metal ion to
a ligand. The higher the log K.sub.1 of a metal ion is, the higher
its binding affinity to the target ligand is. Consistent with the
HSAB principle, the table in FIG. 58 shows that soft metal ions
(e.g. Ag.sup.+ and Au.sup.+) tend to form more stable complexes
with soft ligands containing S donors (e.g. mercaptoethanol) (FIG.
57). In contrast, hard metal ions (e.g. UO.sub.2.sup.2+ and
VO.sup.2+) tend to prefer hard ligands with negatively charged O
donors (e.g. oxalate and catecholate); whereas metal ions of
borderline hardness/softness (e.g. Cu.sup.2+, Ni.sup.2+ and
Co.sup.2+) bind with soft/hard ligands containing nitrogen, oxygen
and sulfur donors [e.g. EDA, oxalate and mercaptoethanol) depending
on their specific affinity toward the ligands. It is worth
mentioning that alkaline-earth metal ions such as Na.sup.+ and
Li.sup.+ have low binding affinities to the ligands listed in the
table; i.e., they preferentially bind to macrocycles and
macropolycyclic ligands with neutral oxygen donors (e.g. crown
ethers and cryptands).
[0153] In embodiments herein described, the mixed matrix filtration
membranes can have embedded dendrimer particles in which the
concentration of the embedded dendrimer particles can be between
about 1 and 50 wt % of the membrane weight as determined by, for
example, x-ray photoelectron spectroscopy of the membranes (see,
e.g. Examples section). In particular, in some embodiments, the
concentration of the embedded dendrimer particles and/or
nanoparticles can be between about 1 and 10 wt %. In particular, in
other embodiments, the concentration of the embedded dendrimer
particles and/or nanoparticles in the matrix can be greater than
about 10 wt %, and more particularly greater than about 20 wt %,
and more particularly greater than about 40 wt %.
[0154] In some embodiments, the concentration of the embedded
dendrimer particles and/or nanoparticles articles can be up to
about 50%. In some embodiments, the concentration of the embedded
dendrimer particles and/or nanoparticles can be between about 25%
to about 50%, above 50%, and also between about 50% and about 60%
(see Examples section).
[0155] In some embodiments, the embedded dendrimer particles\can
have a homogeneous distribution throughout the membrane wherein
similar numbers of nanoparticles are observed within same sized
areas (e.g. in SEM images at the same magnification) throughout
different portions of the membrane (see, e.g. Example section). In
particular, in some embodiments, some (greater than about 5%) the
microparticles and/or nanoparticles can be present as clusters of
nanoparticles as can be observed by imaging the membrane (e.g. with
SEM images of the membrane). In other embodiments, the particles
can be discrete and not detectable as clusters (see. e.g. Example
section).
[0156] In particular, in some embodiments, the filtration membranes
can have particles approximately 1-3000 nm in size as can be
determined, for example, by SEM and AFM imaging (see e.g. Examples
section).
[0157] In particular, in some embodiments, the filtration membranes
herein described can have pores formed by the polymer aggregates
forming the polymer matrix that range in size from approximately
0.5 microns to 10 microns as can be observed by imaging the
membrane, for example, by SEM (see e.g. Example section).
[0158] In some embodiments, the polymer matrix and the dendrimer
particles can be brought together to form membranes comprising the
polymer matrix and the dendrimer particles such that the dendrimer
particles are embedded in the polymer matrix. In particular, in
some embodiments, the formation of the membranes with embedded
dendrimer particles can be accomplished by allowing formation of
polymeric nanoparticle in situ.
[0159] In particular, in some of those embodiments, a method for
making a filtration membrane in situ herein described comprises
preparing a blend comprising the base polymer that will form the
polymeric aggregate and the polymeric particle precursors that will
form the dendrimer particle in a suitable solvent or mixture of
solvents. In embodiments where crosslinking of corresponding
functional groups in the polymeric particle precursor requires an
initiator and/or a crosslinking agent can be added to the blend to
allow crosslinking and formation of the particles and/or the blend
can be maintained under condition allowing formation of the
covalent link between corresponding functional groups.
[0160] Embodiments wherein formation of polymeric particles is
performed in situ allow under appropriate conditions formation of
homogeneous membrane having a concentration of particles up to
about 50% and/or in which fractal formation of nanoparticle is not
detectable. In addition or in the alternative to the particle
distribution, concentration and configuration, filtration membrane
obtainable by in situ formation can have further controllable
features identifiable by a skilled person upon reading of the
present disclosure.
[0161] In some embodiments, the method to prepare a filtration
membrane herein described in situ comprises preparing a base
polymer solution by dissolving the target amount of base polymer in
a suitable and good/compatible solvent. In particular, in in situ
method a good/compatible solvent is a solvent where the base
polymer is substantially soluble wherein the term "substantially
soluble" as used herein with reference to a polymer and a solvent
and/or a composition indicates the ability of the polymer to
dissolve in the solvent and/or composition. Accordingly, the
backbone of the base polymers as herein described can be
substantially soluble in a good solvent when the polymer backbone
and the good solvent have similar Hildebrand solubility parameters
(6) which is the square root of the cohesive energy density:
.delta. = .DELTA. H v - RT V m ##EQU00001##
wherein .DELTA.H.sub.v is equal to the heat of vaporization, R is
the ideal gas constant, T is the temperature, and V.sub.m is the
molar volume. Similarly two solvents or more solvents are
compatible when they have similar solubility parameters. In
particular, similar solubility parameters between a polymer or a
portion thereof and a solvent and/or composition, and similar
solubility parameters between two or more solvents can be found
when the absolute value of the difference between their solubility
parameters is within 1-10% (see also Tables 2 to 4 herein).
[0162] A polymer or portion thereof in accordance with the present
disclosure is partially soluble in a certain solvent or
composition, when the polymer or portion thereof has partially
similar solubility parameters with the solvent or compositions.
Analogously two or more solvents are partially compatible one with
the other when the two or more solvents have partially similar
solubility parameters. Partially similar solubility parameters are
found when the absolute value of the difference between their
solubility parameters is within 5 to 10% (see also Tables 2 to 4
herein).
[0163] A polymer or portion thereof in accordance with the present
disclosure is substantially insoluble in a certain solvent or
composition, when the polymer or portion thereof has dissimilar
solubility parameters with the solvent or compositions. Analogously
two or more solvents are substantially incompatible one with the
other when the two or more solvents have dissimilar solubility
parameters. Dissimilar solubility parameters are found when the
absolute value of the difference between their solubility
parameters is higher than 10% (see also Tables 2 to 4 herein).
[0164] A skilled person will realize that the ability of the
backbone to dissolve in the solvent can be verified, for example,
by placing an amount of the homopolymer or copolymer to be used in
the solvent or composition as herein described, and observing
whether or not it dissolves under appropriate conditions of
temperature and agitation that are identifiable to a skilled
person.
[0165] In particular, an exemplary reference providing solubility
parameters is the website
www.sigmaaldrich.com/etc/medialib/docs/AldrichlGeneral_Information/polyme-
r_solutions.Par.0001.File.tmp/polymer_solutions.pdf [7] at the time
of filing of the present disclosure (see Tables 2-4). More
particularly, a skilled person will know that Sigma-Aldrich and
other chemical companies provide exemplary tables showing exemplary
solubility parameter values for various non-polar compositions and
polymers. A skilled person can also refer to sources such as the
Polymer Handbook to find solubility parameter values Brandrup, J.,
et al., "Polymer handbook". Vol. 1999. 1999: Wiley New York
[8].
TABLE-US-00002 TABLE 2 Table II: Solubility Parameters for
Plasticizers and Solvents (Alphabetical sequence) .delta. H-Bonding
.delta. H-Bonding Solvent (cal/cm.sup.3)F Strength.sup.3 Solvent
(cal/cm.sup.3)1/2 Strength.sup.3 Acetone 9.9 m Dioctyl aebacate 8.6
m Acetonitrile 11.9 p 1,4-Dioxane 10.0 m Amyl acetate 8.5 m
Di(propylene glycol) 10.0 s Aniline 10.3 s Di(propylene glycol) 9.3
m Benzene 9.2 p monomethyl ether Butyl acetate 8.3 m Dipropyl
phthalate 9.7 m Butyl alcohol 11.4 s Ethyl acetate 9.1 m Butyl
butyrate 8.1 m Ethyl amyl ketone 8.2 m Carbon disulfide 10.0 p
Ethyl n-butyrate 8.5 m Carbon tetrachloride 8.6 p Ethylene
carbonate 14.7 m Chlorobenzene 9.5 p Ethylene dichloride 9.8 p
Chloroform 9.3 p Ethylene glycol 14.6 s Cresol 10.2 s Ethylene
glycol diacetate 10.0 m Cyclohexanol 11.4 s Ethylene glycol diethyl
ether 8.3 m Diamyl ether 7.3 m Ethylene glycol dimethyl ether 8.6 m
Diamyl phthalate 9.1 m Ethylene glycol monabutyl ether 9.5 m
Dibenzyl ether 9.4 m (Butyl Cecaove .RTM.) Dibutyl phthalate 9.3 m
Ethylene glycol monoethyl ether 10.5 m Dibutyl sebacate 9.2 m
(Cellosolve .RTM.) 1,2-Dichlorobenzene 10.0 p Furturyl alcohol 12.5
s Diethyl carbonate 8.8 m Glycerol 16.5 s Di(ethylene glycol) 12.1
s Hexane 7.3 p Di(ethylene glycol) monobutyl 9.5 m Isopropyl
alcohol 8.8 m ether (Butyl Carbitol .RTM.) Methanol 14.5 s
Di(ethylene glycol) monoethyl 10.2 m Methyl amyl ketone 8.5 m ether
Carbitol .RTM.) Methylene chloride 9.7 p Diethyl ether 7.4 m Methyl
ethyl ketone 9.3 m Diethyl ketone 8.8 m Methyl isobutyl ketone 8.4
m Diethyl phthalate 10.0 m Propyl acetate 8.8 m Di-n-hexyl
phthalate 8.9 m 1,2-Propylenecarbonate 13.3 m Diisodecyl phthalate
7.2 m Propylene glycol 12.6 s N,N-Dimethylacetamide 10.8 m
Propylene glycol methyl ether 10.1 m Dimethyl ether 8.8 m Pyridine
10.7 s N,N-Dimethylformamide 12.1 m 1,1,2,2-Tetrachloroethane 9.7 p
Dimethyl phthalate 10.7 m Tetrachloroethylene 9.3 p
Dimethylsiloxanes 4.9-5.9 p (perchloroethylene) Dimethyl sulfoxide
12.0 m Tetrahydrofuran 9.1 m Dioctyl adipate 8.7 m Toluene 8.9 p
Dioctyl phthalate 7.9 m Water 23.4 s .sup.2"Polymer Handbook",
Eds.Brandrup, J.; Immergul, E.H.; Grulke, E.A., 4th Edition, John
Wiley, New York, 1999, VII/675-711. Aldrich Catalog Number
Z41,247-3. .sup.3H-Bonding: p = poor; m = moderate: s = strong
TABLE-US-00003 TABLE 3 Table III: Solubility Parameters (.delta.)
for Plasticizers and Solvents (irtereasing .delta. value sequence)
.delta. H-Bonding .delta. H-Bonding Solvent (cal/cm.sup.3).sup.1/2
Strength.sup.4 Solvent (cal/cm.sup.3).sup.1/2 Strength.sup.4
Dimethylsiloxanes 4.9-5.9 p Di(ethylene glycol) monobutyl 9.5 m
Diisodecyl phthalate 7.2 m ether (Butyl Carbitol.RTM.) Hexane 7.3 p
Chlorobenzene 9.5 p Diamyl ether 7.3 m Methylene chloride 9.7 p
Diethyl ether 7.4 m Dipropyl phthalate 9.7 m Dioctyl phthalate 7.9
m 1,1,2,2-Tetrachloroethane 9.7 p Butyl butyrate 8.1 m Ethylene
dichloride 9.8 p Ethyl amyl ketone 8.2 m Acetone 9.9 m Ethylene
glycol diethyl ether 8.3 m 1,2-Dichlorobenzene 10.0 p Butyl acetate
8.3 m Diethyl phthalate 10.0 m Methyl isobutyl ketone 8.4 m
Ethylene glycol diacetate 10.0 m Methyl amyl ketone 8.5 m
Di(propylene glycol) 10.0 s Amyl acetate 8.5 m Carbon disulfide
10.0 p Ethyl n-butyrate 8.5 m 1,4-Dioxane 10.0 m Ethylene glycol
dimethyl ether 8.6 m Propylene glycol methyl ether 10.1 m Carbon
tetrachloride 8.6 p Di(ethylene glycol) monoethyl 10.2 m Dioctyl
sebacate 8.6 m ether (Carbitol .RTM.) Dioctyl adipate 8.7 m Cresol
10.2 s Isopropyl alcohol 8.8 m Aniline 10.3 s Diethyl carbonate 8.8
m Ethylene glycol monoethyl 10.5 m Propyl acetate 8.8 m ether
(Cellosolve .RTM.) Diethyl ketone 8.8 m Pyridine 10.7 s Dimethyl
ether 8.8 m Dimethyl phthalate 10.7 m Toluene 8.9 p
N,N-Dimethylacetamide 10.8 m Di-n-hexyl phthalate 8.9 m
Cyclohexanol 11.4 s Ethyl acetate 9.1 m Butyl alcohol 11.4 s Diamyl
phthalate 9.1 m Acetonitrile 11.9 p Tetrahydrofuran 9.1 m Dimethyl
sulfoxide 12.0 m Dibutyl sebacate 9.2 m Di(ethylene glycol) 12.1 s
Benzene 9.2 p N,N-Dimethylformamide 12.1 m Tetrachloroethylene 9.3
p Furfuryl alcohol 12.5 s (perchloroethylene) Propylene glycol 12.6
s Di(propylene glycol) 9.3 m 1,2-Propylenecarbonate 13.3 m
monomethyl ether Methanol 14.5 s Chloroform 9.3 p Ethylene glycol
14.6 s Dibutyl phthalate 9.3 m Ethylene carbonate 14.7 m Methyl
ethyl ketone 9.3 m Glycerol 16.5 s Dibenzyl ether 9.4 m Water 23.4
s Ethylene glycol monobutyl ether 9.5 m (Butyl Cellosolve .RTM.)
.sup.4H-Bonding: p = poor; m = moderate: s = strong Carbitol and
Cellosolve are registered trademarks of Union Carbide Corp.
TABLE-US-00004 TABLE 4 Table IV: Solubility Parameters for
Homopolymers.sup.5 Repeating Unit .delta.(cal/cm.sup.3).sup.1/2
Repeating Unit .delta.(cal/cm.sup.3).sup.1/2 (Alphabetical
Sequence) (Increasing .delta. value sequence) Acrylonitrile 12.5
Tetrafluoroethylene 6.2 Butyl acrylate 9.0 Isobutyl methacrylate
7.2 Butyl methacrylate 8.8 Dimethylsiloxane 7.5 Cellulose 15.6
Propylene oxide 7.5 Cellulose acetate (56% Ac groups) 27.8
Isobutylene 7.8 Cellulose nitrate (11.8% N) 14.8 Stearyl
methacrylate 7.8 Chloroprene 9.4 Ethylene 8.0 Dimethylsiloxane 7.5
1,4-cis-Isoprene 8.0 Ethyl acrylate 9.5 Isobornyl methacrylate 8.1
Ethylene 8.0 Isoprene, natural rubber 8.2 Ethylene teraphthalate
10.7 Lauryl methacrylate 8.2 Ethyl methacrylate 9.0 Isobornyl
acrylate 8.2 Formaldehyde (Oxymethylene) 9.9 Octyl methacrylate 8.4
Hexamethylene actiparnide (Nylon 6/6) 13.6 n-Hexyl methacrylate 8.6
n-Hexyl methacrylate 8.6 Styrene 8.7 Isobornyl acrylate 8.2 Propyl
methacrylate 8.8 1,4-cis-Isoprene 8.0 Butyl methacrylate 8.8
Isoprene, natural rubber 8.2 Ethyl methacrylate 9.0 Isobutylene 7.8
Butyl acrylate 9.0 Isobornyl methacrylate 8.1 Propyl acrylate 9.0
Isobutyl methacrylate 7.2 Propylene 9.3 Lauryl methacrylate 8.2
Chloroprene 9.4 Methacrylonitrile 10.7 Tetrahydroluran 9.4 Methyl
acrylate 10.0 Methyl methacrylate 9.5 Methyl methacrylate 9.5 Ethyl
acrylate 9.5 Octyl methacrylate 8.4 Vinyl chloride 9.5 Propyl
acrylate 9.0 Formaldehyde (Oxymethylene) 9.9 Propylene 9.3 Methyl
acrylate 10.0 Propylene oxide 7.5 Vinyl acetate 10.0 Propyl
methacrylate 8.8 Methacrylonitrile 10.7 Stearyl methacrylate 7.8
Ethylene terephthalate 10.7 Styrene 8.7 Vinylidene chloride 12.2
Tetrafluoroethylene 6.2 Acrylonitrile 12.5 Tetrahydrofuran 9.4
Vinyl alcohol 12.6 Vinyl acetate 10.0 Hexamethylene
adiparnide(Nylon 6/6) 13.6 Vinyl alcohol 12.6 Cellulose nitrate
(11.8% N) 14.8 Vinyl chloride 9.5 Cellulose 15.6 Vinylidene
chloride 12.2 Cellulose acetate (56% Ac groups) 27.8 .sup.5Values
reported are for homopolymers of the Repeating Unit. Reported
.delta. values vary with the method of determination and test
conditions. Averaged values are given in this table.
[0166] Additional exemplary empirical solubility parameters (e.g.
Flory Huggins are identifiable by a skilled person (see, e.g.,
Brandrup, J., et al., "Polymer handbook". Vol. 1999. 1999: Wiley
New York [8], and other available references known or identifiable
by one skilled in the art)) Exemplary good solvents for the
exemplary base polymer PVDF comprise Tetrahydrofuran, Methyl EThyl
Ketone, Dimethyl formamide, Dimethyl acetamide, Tetramethyl urea,
Dimethyl Sulfoxide, Trimethyl phosphate, N-Methyl-2-Pyrrolidone.
Additional indication concerning good solvents for a PVDF polymer
can be found in F. Liu et al./Journal of Membrane Science 375
(2011) 1-27 [9]. A skilled person can determine if other solvents
would be good solvents for PVDF or if other base polymers or other
polymers (e.g. functionalizing polymers their precursor, polymeric
particle precursors) would be substantially soluble in these
solvents or other solvents or compositions by applying the same
calculations using the particular solubility parameters for the
particular solvent and/or composition.
[0167] Exemplary linear polymers that can be used as building
blocks for the base polymer of membranes with in-situ generated
dendrimer particles include polyvinylidene fluoride (PVDF),
polyethersulfone (PES), polysulfone (PSf), polyacrylonitrile (PAN)
and polyamides (PAM) and additional polymer of formula (I) herein
described. Good solvents for these polymers are expected to
comprise n-methyl-2-pyrrolidone (NMP), dimethyl formamide (DMF),
dimethyl acetamide (DMAc), triethyl phosphate (TEP) and dimethyl
sulfoxide (DMSO).
[0168] The method further comprises adding a polymeric particle
precursor in the base polymer solution to obtain a blend and in
particular a dispersion of particle precursor in the base polymer
solution. Given a certain base polymer solution a particle
precursor can be selected to have: a portion substantially soluble
in a solvent (or mixture of solvents) compatible with that used to
dissolve the base polymer and a portion substantially insoluble
with said solvent. Accordingly, the particle precursor can be
selected for the ability to form dispersed/segregated domains and
in particular aggregates of surfactant molecules (e.g. micelles)
dispersed in the base polymer solution as will be understood by a
skilled person. Exemplary expected membrane particle precursors
include functional monomers/polymers, block copolymers: branched
polymers/dendrimers. Preferred particle precursors include
aliphatic amines, aromatic amines, anhydrides, polyamines (linear,
branched and dendritic) and epoxides and other compound presenting
hydroxyl groups.
[0169] A variety of low-generation dendrimers and coupling agents
(for example, crosslinkers) can be utilized as precursors for the
preparation of dendrimer particles in a membrane casting solution.
FIGS. 9-14 list selected low-generation dendrimers from several
commercial sources.
[0170] In some embodiments, preparing a base polymer solution and
adding a particle precursor is performed to control the sizes of
the segregated domains of precursor particles, which on their turn
control the sizes of the in-situ synthesized dendrimer particles
and/or nanoparticles. In particular, with the in situ method the
dendrimer particles and/or nanoparticles can be synthesized which
have a diameter in a range of from approximately 10-100 nm to
approximately 2-4 .mu.m and depend on several factors including the
(i) chemistry and molecular weight of the particle precursor, (ii)
intensity and duration of mixing (e.g. sonication versus slow
stirring) and (ii) the addition of a dispersion stabilizer (e.g.
surfactant). For example, a mixture of (i) base polymer and
solvent, (ii) particle precursor formed by a monomer/oligomer of
[molecular weight (M.sub.n) of 100-10001 and (iii) a surfactant
(e.g. sodium dodecyl sulfate) is expected to be sonicated to
prepare a membrane casting solution containing segregated domains
of particle precursors of 10-100 nm in sizes. In contrast, the slow
stirring of a mixture of base polymer and solvent and (ii)
monomer/polymer [Molecular weight (M.sub.n) of 300-100000] is
expected to be required to prepare a membrane dope containing
segregated domains of particle precursors of sizes ranging from 0.5
to 4 .mu.m depending on the specific combination of based polymer,
polymer particles precursor and/or stirring conditions.
[0171] The method to prepare dendrimer particles by coupling
low-generation dendrimers in a membrane casting solution varies
depending on the chemistry of the dendrimer terminal groups (e.g.
amines, carboxylic acids, azides, thiols and acrylates). The
methods can include (i) EDC coupling (FIG. 15), (ii) click
chemistry (FIG. 16) and (iii) in-situ polymerization using an
initiator (FIG. 17
[0172] In some embodiments, the method to prepare an in situ
membrane further comprises adding crosslinker and/or an initiator
capable of reacting with the polymer particle precursor to the
blend to synthesize the polymeric particles in a membrane casting
solution formed by a base polymer a solvent, polymeric particle
precursor and the crosslinker and/or/initiator.
[0173] A cross-link is a bond that links one polymer chain to
another. They can be covalent bonds or ionic bonds. Exemplary
crosslinkers include diacrylates, dimethacrylates, diepoxides,
dihalides, diisocyanates, diacyl chlorides, dianhydrides.
[0174] Preferred crosslinkers include diepoxides, dihalides, diacyl
chlorides and dianhydrides with small molecular weights (Mn of
90-300). Preferred crosslinker monomers include epoxides, acrylics,
amines, acid chlorides and others that can be used to prepare
polymeric particles in solutions herein described. Exemplary
crosslinkers for particle formation herein described comprise the
compounds described in Table 5 corresponding to Table 2 of U.S.
Pat. No. 7,459,502 [10].
TABLE-US-00005 TABLE 5 Structure Mw Stucture Mw ##STR00001## 92.52
##STR00002## 178.49 ##STR00003## 174.19 ##STR00004## 240.99
##STR00005## ##STR00006## 127.01 ##STR00007## 302.37 ##STR00008##
203.02 ##STR00009## 297.27 ##STR00010## 203.02 ##STR00011## 277.32
##STR00012## 265.48 ##STR00013## 86.09 ##STR00014## 154.98
##STR00015## 202.25 ##STR00016## 198.13 ##STR00017## 184.41
##STR00018## ##STR00019## 175.06 ##STR00020## 112.08 ##STR00021##
112.99 ##STR00022## 194.19 ##STR00023## 168.2 ##STR00024## 234.2
##STR00025## 118.16 ##STR00026## 252.22 ##STR00027## 249.27
##STR00028## 194.19 ##STR00029## 168.19 ##STR00030## 178.14
##STR00031## 174.16 ##STR00032## 108.53 ##STR00033## 188.18
##STR00034## 222.28 ##STR00035## 86.09 ##STR00036## 158.16
##STR00037## 146.14
[0175] An initiator indicates a source of any chemical species that
reacts with a monomer (single molecule that can form chemical
bonds) to form an intermediate compound capable of linking
successively with a large number of other monomers into a polymeric
compound. The most widely used initiators produce free radicals
(reactive atoms or groups of atoms that contain odd numbers of
electrons); examples include peroxides and aliphatic azo compounds
used to polymerize vinyl chloride, methyl methacrylate, and other
monomers. Acid-forming systems such as boron trifluoride with
traces of water react with a monomer to produce a positively
charged (cationic) intermediate. Such initiation is used in the
conversion of isobutylene to butyl rubber. Reaction of metallic
sodium and biphenyl produces an anionic initiator that causes
formation of polymer chains with reactive sites at both ends; these
may be further treated with a different monomer to yield block
copolymers. For example, Polypropylene and high-density
polyethylene are prepared by use of Ziegler catalysts, which are
initiators composed of organometallic compounds and metallic
halides, such as triethylaluminum and titanium tetrachloride.
[0176] An exemplary initiator capable of reacting with a polymeric
particle precursor herein described is benzyl chloride. Additional
initiators can be identified by a skilled person in view of
information known to a skilled person (see e.g. M. Talha Gokmen,
Filip E. Du Prez*Progress in Polymer Science 37 (2012) 365-405
[11]) and the content of the present disclosure. Additional methods
and techniques to make polymeric particles known to a skilled
person (e.g. Strathmann, Introduction to Membrane Science and
Technology. Wiley-VCH Verlag: Weinheim, 2011, and V. Mittal, (Ed).
Advanced Polymer Nanoparticles-Synthesis and Surface Modifications.
CRC Press: Boca Raton (Fla.). 2011, Chap 1, 1-28 [12]) can also be
adapted to in situ particle formation by modifications that allow
to avoid precipitation.
[0177] In some embodiments, the method further comprises performing
membrane preparation by phase inversion casting by mixing the dope
with a non-solvent (a solvent substantially incompatible with the
base polymer solvent). Note that the membrane can be casted onto a
suitable support (e.g. s glass plate) and then peeled off to form a
self-supporting membrane. Alternatively, the membrane can be casted
onto a microporous [e.g. polyethylene terephthalate (PET)] support,
a layer of a multilayered membrane or another membrane (e.g. a
mesh) to form a bicomposite membrane herein described.
[0178] In some embodiments, the concentration of base polymer in
the membrane is not less than about 40%, and preferable not less
that about 50%, In some embodiments the concentration of polymeric
particles is about 50% possibly about 60%. In some embodiments the
concentration of polymeric particles is not more than 60% to
conserve the support to the membrane provided by the porous
polymeric aggregate formed by the base polymer.
[0179] In some embodiments, the polymer that will form the porous
polymer aggregate can be selected based on desired features such as
morphology, structural strength, and others known to a skilled
person [13] as well as compatibility based on thermodynamic
parameters identifiable to a skilled person. For example, one
desired feature can be the presence of skin layers on either side
of the membrane when observed in cross section (see e.g. FIG. 21-23
of the instant application and FIG. 6 of related application U.S.
Ser. No. 13/754,883 published as US20130213881). In particular, the
thickness of one of the skin layers can be decreased by increasing
the amount of polymer to form the polymeric nanoparticles in the
blend of polymer to form the polymeric nanoparticles and polymer to
form the polymer matrix (see, e.g. Example 5 and FIG. 21 of the
instant application and Example 2 and FIG. 6 of related application
U.S. Ser. No. 13/754,883 published as US20130213881).
[0180] For example, another desired feature can be particle size.
In particular, the size of the dendrimer particles can be decreased
by increasing the amount of polymer to form the polymeric
nanoparticles in the blend of polymer to form the polymeric
nanoparticles and polymer to form the polymer matrix (see, e.g.
Example 1 and FIGS. 4-7 of the related U.S. Ser. No. 14/447,574 and
Example 2 and FIG. 6 and FIG. 7 related application U.S. Ser. No.
13/754,883 published as US20130213881).
[0181] For example, another desired feature can be porosity as
determined by imaging (e.g. with SEM) of the surface of the
membrane. In particular, the number of pores can be increased by
increasing the amount of polymer as well as the type of polymer to
form the dendrimer particles in the blend of polymer to form the
polymeric nanoparticles and polymer to form the polymer matrix
(see, e.g., Example 5 and FIGS. 22-26 of the instant application,
Example 1 and FIG. 4, FIG. 5, FIG. 6 and FIG. 7 of U.S. Ser. No.
14/447,574 and Example 2 and FIG. 7 of related application U.S.
Ser. No. 13/754,883 published as US20130213881).
[0182] Factors to be considered comprise having a solubility
parameter (see, e.g., [7, 14, 15]) similar to that of polymer that
will form the polymeric nanoparticles, as well as favorable
interactions between the comprising the polymer that will form the
polymer matrix and the polymer that will form the polymeric
nanoparticles. In particular, the similarity of solubility
parameters can ensure that the polymer forming the polymeric
nanoparticles is sufficiently distributed in the blend of polymer
that will form the polymeric nanoparticles and polymer that will
form the polymer matrix (as determined, for example, by inspection
of the turbidity and viscosity of the blend) such that a membrane
with a desired concentration of nanoparticles is obtained. For
example, in embodiments, wherein a concentration of greater than
about 20 wt % is desired, PVDF or other fluorinated polymer can be
chosen as the polymer for the polymer matrix. In another example
wherein a membrane with similar features is desired a poly(ether
sulfone) polymer or other polymer with ether groups and/or sulfonyl
and/or carbonyl groups can be chosen as the polymer for the polymer
matrix thus providing a homogeneous blend adapted to form
particles, and in particular discrete particles, in situ when a
cross-linker is added to the blend form a dope with homogeneously
distributed discrete to form the membrane as described herein (see,
e.g., Example 2 of the instant application, Example 1 and 2 of U.S.
Ser. No. 14/447,574 and Examples 1-3 and 21 of related application
U.S. Ser. No. 13/754,883 published as US20130213881).
[0183] In particular, the in situ formation of the microparticles
and/or nanoparticles can be controlled by parameters such as
relative concentration of the polymers to form the matrix and
nanoparticles and cross linker (see. e.g. Example 2 of the instant
application, Examples 1 and 2 of U.S. Ser. No. 14/447,574 and
Example 21 of related application U.S. Ser. No. 13/754,883
published as US20130213881) such that the membranes produced have
discrete particles in which formation of nanoparticle clusters is
minimized (see e.g. FIG. 58B of related application U.S. Ser. No.
13/754,883 published as US20130213881) as well as fractal growth as
can occur in membranes when the particles are preformed and blended
with the polymer that will form the polymer matrix. In particular,
the membranes with in situ generated nanoparticles can have
nanoparticles in concentrations exceeding about 20 wt % and in
particular, exceeding about 40 wt %.
[0184] In particular, in some embodiments, membrane compositions,
methods and applications herein described comprise (i) a linear
polymer (e.g. poly(vinylidinefluoride) [PVDF]) as base membrane
polymer, (ii) a polyamine (e.g. G0 or G1 Poly(amidoamine) (PAMAM)
as polymeric particle precursor, (iii) a crosslinker, (e.g. an
epoxide such as epichlrohydrin [ECH])) and (iv) an initiator (e.g.
hydrochloric acid (HCl).
[0185] In other embodiments, filtration membranes herein described
can be formed by a process wherein nanoparticles can be added to
the membrane ex situ in addition or in the alternative to
nanoparticles formed with the in sin method. In particular, in some
of these embodiments, the nanoparticles can be performed by cross
linking suitable polymeric nanomaterial separately from the polymer
forming the matrix (see e.g. Examples 4, 5, and 14 of related
application U.S. Ser. No. 13/754,883 published as US20130213881)
and then mixed with the polymer that will form the polymer matrix
to form a dope with preformed polymeric nanoparticles. The method
can further comprise casting the dope to form the membranes as
described herein (see, e.g., Examples 1 and 20 of U.S. Ser. No.
14/447,574). In particular, the membranes made with preformed
nanoparticles in the dope can have clusters of nanoparticles (see
e.g. FIG. 58B of related application U.S. Ser. No. 13/754,883
published as US20130213881) from fractal growth. In particular, the
membranes with ex sine generated preformed nanoparticles can have
nanoparticles in concentrations between about 1 wt % and about 10
wt %.
[0186] In some embodiments, the polymer aggregate of the polymer
matrix can be formed by a polymer having a formula
##STR00038##
wherein:
[0187] Q, Y, and Z comprise saturated aliphatic hydrocarbon,
aromatic hydrocarbon, or unsaturated aliphatic hydrocarbons;
[0188] m, l, and k independently are integers ranging between
0-50;
[0189] at least one of m, l, k is not equal to zero;
[0190] j is an integer ranging between 50-500; and
[0191] at least one of Q (when Q.noteq.0), Y (when Y.noteq.0), or Z
(when Z.noteq.0), comprises the polymer corresponding functional
group.
[0192] The term "saturated aliphatic hydrocarbon" as used herein
refers to a hydrocarbon comprising, carbon atoms that are joined
together in straight chains, branched chains, or non-aromatic rings
in which the carbon-carbon bonds are saturated with hydrogen (e.g.
methane, ethane, propane, isobutane, and butane). For example, in
saturated aliphatic hydrocarbons have a general formula of
C.sub.nH.sub.2n+2 for acyclic saturated aliphatic hydrocarbons and
C.sub.nH.sub.2n cyclic saturated aliphatic hydrocarbons. Saturated
aliphatic hydrocarbon can be substituted with one or other
elements, for example, N, O, S, P, F, Cl, Br, and I.
[0193] The term "aromatic hydrocarbon" as used herein refers to a
hydrocarbon comprising a conjugated ring of unsaturated bonds, lone
pairs, and/or empty orbitals which can exhibit a stabilization
stronger than expected by the stabilization by conjugation alone.
An exemplary aromatic compounds is benzene which is a six-membered
ring having alternating double and single bonds between carbon
atoms. Aromatic hydrocarbons can be monocyclic (MAH) (e.g. benzene)
or polycyclic (PAH) (e.g. naphthalene, anthracene, pyrene).
Aromatic hydrocarbons can be substituted with one or other
elements, for example, N, O, S, P, F, Cl, Br, and I.
[0194] The term "unsaturated aliphatic hydrocarbon" as used herein
refers to a hydrocarbon comprising carbon atoms that are joined
together in straight chains, branched chains, or non-aromatic rings
and comprise at least one of a double or a triple bond between
adjacent carbon atoms, referred to as "alkenes" and "alkynes",
respectively. An unsaturated hydrocarbon can comprise one or more
of double or triple bonds. In hydrocarbons having more than one
double or triple bond, the unsaturated hydrocarbon can be
conjugated (e.g. 1,4-hexadiene) or can be isolated (e.g.
1,5-hexadiene). In hydrocarbons comprising internal alkenes, the
alkenes can be in a "cis" or a "trans" configuration (e.g.
trans-2-butene or cis-2-butene). Unsaturated aliphatic hydrocarbon
can be substituted with one or other elements, for example, N, O,
S, P, F, Cl, Br, and I.
[0195] In particular in some embodiments, Q, Y, and Z in formula
(I) can independently selected from the following formulas:
##STR00039##
wherein:
[0196] n=0 or 1;
[0197] m, is an integer ranging from 0-15;
[0198] X is a functional group comprising an atom selected from O,
S, N, P, or F; and
[0199] R.sub.1-R.sub.18 are independently selected from: the
polymer component functional group; hydrogen: C.sub.1-C.sub.20
linear, branched, saturated, unsaturated, or aryl hydrocarbon which
are either substituted or unsubstituted with O, N, B, S, P; or
substituted O, N, B, S, or P:
[0200] and at least one of R.sub.1-R.sub.18 is the polymer
corresponding functional group attaching the dendrimer
component.
[0201] Exemplary linear polymer materials for producing a polymeric
aggregate made from linear polymers herein described comprise
polysulfone (PS), polyether sulfone (PES), poly(vinylidene)
fluoride (PVDF), poly(tetrafluoroethylene) (PTFE),
poly(acrylonitrile) (PAN), poly(methacrylic acid) (PMAA),
poly(acrylic acid) (PAA), poly(vinyl methyl ketone), and
poly(ethylene terephthalate) (PET).
[0202] In some embodiments, the polymer forming the polymeric
microparticles and/or nanoparticles embedded in the polymer matrix
can be one or more polymers of formula (I) covalently linked (e.g.
by a suitable initiator to form microparticles and/or
nanoparticles). In particular, exemplary linear polymer materials
for producing polymeric nanoparticles made from linear polymers
herein described comprise polysulfone (PS), polyether sulfone
(PES), poly(vinylidene) fluoride (PVDF), poly(tetrafluoroethylene)
(PTFE), poly(acrylonitrile) (PAN), poly(methacrylic acid) (PMAA),
poly(acrylic acid) (PAA), poly(vinyl methyl ketone), and
poly(ethylene terephthalate) (PET). Additional polymers suitable as
a polymer component herein described comprise polymers which can be
used as base polymers in the fabrication of commercial UF/MF
membranes, polymer which is either partially soluble or can be
dispersed in solvents with different physicochemical properties
together with nanoparticles according to the disclosure, and
polymers which can be functionalized, which are identifiable by a
skilled person upon reading of the present disclosure (see e.g. [7,
12, 14]).
[0203] Suitable polymeric nanoparticles according to embodiments
herein described can be selected for a given polymer matrix based
on compatibility with the polymer aggregate which can be determined
based on the presence of corresponding functional group capable of
attachment as well as possibly other features such as solubility of
the polymer that forms the polymeric nanoparticles for in situ
nanoparticle formation (or solubility of the preformed polymeric
nanoparticles for preformed nanoparticle formation) together with
the polymer that forms the polymer matrix in a particular solvent
or mixture of solvents, affinity of the dendritic component for
polymeric component, and/or stability of the dendritic component in
a solvent to be used in the fabrication of the membrane. By way of
example, compatibility can be determined by the polymeric
nanoparticle possessing functional groups (e.g. amine groups or
carboxylic acid or hydroxyl groups) capable of interacting with
functional groups on the polymer matrix (e.g. fluoride atoms or
oxygen atoms) and/or by the polymers used to make the polymer
matrix and polymeric nanoparticles having similar solubility
parameters (see e.g. [7, 12, 14]). In particular, if the polymeric
nanoparticle possesses amine groups (e.g. PMAM, PPI, or bis-MPA)
then a polymer to form the polymer matrix can be chosen which
possesses fluoride atoms; if the polymeric nanoparticle possesses
carboxylic acid or hydroxyl groups (e.g. MPA or bis-MPA
polyester-16-hydroxyl) then a polymer to form the polymer matrix
can be chosen which possesses oxygen atoms (e.g. a poly(sulfone) or
poly(ether sulfone) polymer).
[0204] In some embodiments, the polymers that can be used as
polymeric particle precursor to form dendrimer particles herein
described can be a branched low-generation dendritic molecules and
in particular the branched low-generation dendritic molecules
according to general formula (XI) for a dendrimer core having four
anchor atoms.
##STR00040##
wherein: m.sub.2 is an integer ranging from 1-4; R.sub.19-R.sub.22
are branch cell units, each branch cell unit comprising a head
attachment atom and one to four tail attachment atoms joined to
form a chemical moiety wherein the head attachment atom and one to
four tail attachment atoms are linked by covalent bond, such as
carbon-nitrogen bond of an amide, carbon-oxygen bond an ester,
carbon-carbon single or double bond.
[0205] FG1 and FG2 are terminal functional groups, independently
selected from amines, hydroxyl group, carboxylic acids, azides,
thiols, diacetylenyl, and acrylates. The FG1 and FG2 groups can be
the same or different.
L.sub.1 is equal to 2m.sub.1; and Q.sub.1 is a core, having a
formula selected from:
##STR00041##
wherein n.sub.2 is an integer from 1 to 18
[0206] In formula (XI), the dendrimer core Q has four anchor atoms
connecting to the branch cell units. In some other embodiments, the
dendrimer core can have two to six anchor atoms.
[0207] In embodiments of the precursor of formula (XI), FG1 and FG2
are directly or indirectly attached to the terminal groups of the
outmost shell of the dendritic molecules. In embodiments herein
described 2l.sub.1=Z wherein Z is the number of terminal functional
groups.
[0208] In some embodiments, a branch cell unit can include
amidoamine groups or ester hydroxyl groups.
[0209] In some embodiment, the head attachment atom and tail
attachment atom of a successive branch cell unit can form a
chemical group selected from one of
1,4-disubstituted-1,2,3-triazole, carbonato (--O--(CO)--O--),
carbamoyl (--(CO)--NH--), thiocarbamoyl (--(CS)--NH--), carbamido
(--NH--(CO)--NH--), carbamate (--O(CO)--NH--), imino (--CR.dbd.N--)
where R.dbd.C.sub.1-C.sub.12 alkyl, C.sub.5-C.sub.12 aryl,
C.sub.6-C.sub.12 alkaryl, C.sub.6-C.sub.12 aralkyl), boronato
(--B(OR)O--) wherein R.dbd.C.sub.1-C.sub.12 alkyl, C.sub.5-C.sub.12
aryl, C.sub.6-C.sub.12 alkaryl, C.sub.6-C.sub.12 aralkyl),
phosphonato (--P(O)(O.sup.-)OR--, wherein R.dbd.C.sub.1-C.sub.12
alkyl, C.sub.5-C.sub.12 aryl, C.sub.6-C.sub.12 alkaryl,
C.sub.6-C.sub.12 aralkyl), and chemical group form by any coupling
chemistry that is known to a person of skill.
[0210] In some embodiment, a branch cell unit of head attachment
atom and tail attachment atoms can be an alkyl, aryl, substituted
aryl aromatic (e.g. benzene, naphthalene, anthracene or others
identifiable to a skilled person) or aliphatic (e.g. cyclobutane,
cyclopentane, cyclohexane, decalin, or others identifiable to a
skilled person), spirane, fused rings.
[0211] In some embodiment, a branch cell unit of head attachment
atom and tail attachment atoms can be C1-C15 alkyl; branched linear
C3-C15 alkyl: cyclic C3-C15 alkyl; linear, cyclic, or branched
C2-C15 alkenyl; linear, cyclic, or branched C2-C15 alkynyl; C6-C20
substituted or unsubstituted aryl: and C6-C20 substituted or
unsubstituted heteroaryl groups.
[0212] Examples of heteroaryl groups include pyrrolyl,
pyrrolidinyl, pyridinyl, quinolinyl, indolyl, pyrimidinyl,
imidazolyl, and examples of heteroatom-containing alicyclic groups
are pyrrolidino, morpholino, piperazino, piperidino groups.
[0213] In some embodiment, a branch cell unit of head attachment
atom and tail attachment atoms can be aryl groups having 5 to 24
carbon atoms, or aryl groups can contain 5 to 14 carbon atoms.
Exemplary aryl groups can contain one aromatic ring or two fused or
linked aromatic rings, e.g., phenyl, naphthyl, biphenyl,
diphenylether, diphenylamine, benzophenone, and the like.
[0214] In particular, in some embodiments, the low-generation
dendrimers according to some embodiments have the general formula
XV below:
##STR00042##
m.sub.3 is an integer from 1 to 4,
X.sup.1 is N:
[0215] R.sub.23-R.sub.26 are independently amidoamine groups; FG1
and FG2 are terminal groups, independently selected from amines,
hydroxyl group, carboxylic acids, azides, thiols, diacetylenyl, and
acrylates, and connected to each of the R.sub.23, R.sub.24,
R.sub.25 and R.sub.26; n.sub.3 is an integer from 1 to 18 and
L.sub.2 is equal to 2m.
[0216] In embodiments herein described in polymeric particle
precursor of formula (XV) 2l=Z wherein Z is the number of terminal
functional groups.
[0217] More particularly, in some embodiments, the low-generation
dendrimers according to some embodiments have the general formula
XVI below:
##STR00043##
wherein n.sub.4 is an integer from 2-10: p.sub.1 and P.sub.2 are
independently an integer from 2-5: m.sub.4 is an integer from 1-4;
l.sub.3 is equal to 2m.sub.4: FG1 and FG2 are terminal groups,
independently selected from amines, carboxylic acids, azides,
thiols, diacetylenyl, and acrylates.
[0218] In embodiments herein described in polymeric particle
precursor of formula (XVI) 2l.sub.3=Z wherein Z is the number of
terminal functional groups.
[0219] In some embodiments, the low-generation dendrimer to form
dendrimer particles according to some embodiments comprises a core,
a plurality of arms extending from the core, the arms having a
branched structure, and within the branched structure, a plurality
of units satisfying having the formula:
##STR00044##
where Z.sub.2 and Z.sub.3 are independently a C1 to C20 substituted
or unsubstituted alkyl or aromatic moiety wherein Z.sub.2 comprises
no nitrogen atoms that are simultaneously bound to two or more
carbon atoms, for example, secondary and tertiary amines or
amides.
[0220] In some embodiments the dendritic component comprises the
formula:
##STR00045##
where n.sub.5 is an integer ranging from 2-5, each of Q.sub.1 and
Q.sub.2 comprises linear or branched polymer moiety, and R.sub.27
to R.sub.34 are independently selected from hydrogen, an
substituted or unsubstituted alkyl or aromatic group, or a
substituted or unsubstituted 2-hydroxyalkyl group.
[0221] In particular, in some embodiments, when groups Z.sub.1,
Z.sub.2, Z.sub.3 and Q.sub.1, Q.sub.2 and Q.sub.3 of formulas
XI-XVIII comprise linear or branched polymer moieties with amino
and/or alcohol groups, the molecules can be converted to
nano/microparticles by cross linking the molecules with
cross-linking reagents described herein (e.g. 1,3-dibromopropane or
epichlorohydrin) using inverse micelles as described herein (see
e.g. Examples). In particular, in some embodiments, the formation
of the particles can occur by blending polymers that comprise the
polymer matrix with polymers that form the polymeric nanoparticles
to form a blend, and adding a cross-linker to form a dope with in
situ generated dendrimer particles, and in particular dendritic
nanoparticles as described herein (see, e.g. Examples 1 and 2).
[0222] In particular, in some embodiments, the branched dendritic
molecules to form polymeric nanoparticles can comprise low
generations of poly(amidoamine) (PAMAM) dendrimers (for example,
G0, G1, G2 or G3 PAMAM); low generations of poly(propyleneimine)
(PPI) (for example, G1 or G2 PPI); low generation
2,2-bis(methylol)propionic acid (bis-MPA); 2
cyclotriphosphazene-phenoxymethyl(methylhydrazono) (PMMH) dendrimer
(G1 PMMH) and other low-generation dendrimers of various core
chemistry and terminal groups are shown in FIGS. 9-14.
[0223] Suitable polymer components comprising the polymer matrix
can be selected for a given dendritic component based on
compatibility which can be determined based on the presence of
corresponding functional group capable of attachment as well as
possibly other features such as thermodynamic parameters such as
solubility of the polymer component together with the dendrimer
component in a particular solvent or mixture of solvents, affinity
of the polymer component for the dendritic component (e.g. the
ability to hydrogen bond or have an electrostatic attraction),
and/or stability of the polymer component in a solvent to be used
in the fabrication of the membrane.
[0224] In some embodiments, the dendrimer particles formed by
polymeric particle precursor of formula (XI) herein described can
have in the following formula:
##STR00046##
m.sub.5, m.sub.6, or m.sub.7 are independently an integer selected
from 1-4: l.sub.3 is equal to 2 ms; l.sub.4 is equal to 2 m.sub.6:
l.sub.5 is equal to 2 m.sub.7; R.sub.35-R.sub.46 are branch cell
units each independently comprising a head attachment atom and one
to four tail attachment atoms joined to form a chemical moiety
wherein the head attachment atom and one to four tail attachment
atoms are linked by covalent bond, the branch cell unit chemical
moiety comprising amidoamine groups and/or ester hydroxyl groups;
Q.sub.4, Q.sub.5 and Q.sub.6 are independently a core, having a
formula selected from:
##STR00047##
wherein n.sub.2 is an integer from 1 to 18 FG1 and FG2 are terminal
functional groups, independently selected from amines, hydroxyl
group, carboxylic acids, azides, thiols, diacetylenyl, and
acrylates. In particular. FG1 and FG2 are cross-linked to one
another either directly or indirectly via a cross-linking
agent.
[0225] In embodiments of dendrimer particle of formula (XIX)
l.sub.3+l.sub.4+l.sub.5=Z wherein Z is the number of terminal
functional groups. In embodiments of dendrimer particle of formula
(XIX), the head attachment atom and tail attachment atom of each
cell unity can be a covalent bond such as carbon-nitrogen bond of
an amide, carbon-oxygen bond an ester, carbon-carbon single or
double bond.
[0226] In filtration membranes herein described, nanoparticles
formed by a linear or dendritic polymers, are attached to the
polymer component of the polymer matrix typically through a
covalent and/or a hydrogen bond. For example, in some embodiments,
when the polymeric components of formulas I-XI comprise fluorine
and/or sulfonyl groups (e.g. PVDF or PES), dendritic components of
formulas XII-XV comprising amino groups can attach to the polymeric
component through hydrogen bonds from the amino hydrogen atoms to
the fluorine or carbonyl oxygen atoms. In other embodiments, when
the polymeric components comprise oxygen groups (e.g. ethers,
carbonyls, and sulfonyls), dendritic components comprising hydroxyl
or carboxylic acid groups can attach to the polymeric component
through formation of hydrogen bonds.
[0227] In particular, in embodiments of the filtration membrane
herein described, the nanoparticles of the matrix are embedded in
the polymer aggregate of the polymer matrix to present reactive
sites in the membrane.
[0228] The term "present" as used herein with reference to a
compound or functional group indicates attachment performed to
maintain the chemical reactivity of the compound or functional
group as attached. Accordingly, a functional group presented on a
surface, is able to perform under the appropriate conditions the
one or more chemical reactions that chemically characterize the
functional group.
[0229] The term "reactive site" as used herein refers to a chemical
functional group capable of attracting, rejecting, and/or binding
to a chemical of interest. In particular, reactive sites herein
described are able to attract, reject or bind selectively a
chemical to be filtered. Exemplary functional groups suitable as
reactive sites include, but are not limited to, amines, quaternary
ammonium groups, amides, hydroxyl groups, ethers, carboxylates,
esters, sulfonates, sulfiniates, sulfonate esters, sulfinate
esters, sulfonamides, sulfonamides, phosphates, carbamates, ureas,
imidines, guanidines, oximes, imidazoles, pyridines, thiols,
thioethers, thiocarboxylates, and phosphines.
[0230] In particular, in some embodiments, the reactive sites can
be located on the functional groups of the linear polymer forming
the polymeric nanoparticles. By way of example, the reactive sites
can comprise carboxylic acid groups in polymeric nanoparticles
formed with a linear polymer such as poly(methacrylic acid).
[0231] In particular, in some embodiments, the reactive site can be
located on a dendrimer forming the dendrimer polymeric
nanoparticles (for example, amino groups on PAMAM or carboxylic
acid groups on MPA) without any chemical transformation being
necessary. In other embodiments, one or more reactive sites can be
introduced into the dendritic component after a chemical
transformation. Exemplary chemical transformations suitable for the
introduction of a reactive site comprise reductive amination of
amine groups to form alkylated amino groups, alkylation of amines
to form quaternary ammonium groups, alkylation of hydroxyl groups
to form ethers, reaction of amines or hydroxyls with haloalkyl
carboxylic acids and/or derivatives (such as, for example,
2-chloroacetic acid or methyl 2-chloroacetate) to form carboxylic
acids and/or derivatives, reaction of amines or hydroxyls with
haloalkyl sulfonic acids and/or derivatives (such as, for example,
2-(chloromethyl)sulfonic acid or methyl 2-(chloromethyl)sulfonate
to form sulfonic acids and/or derivatives, and reaction of amines
with epoxides to form alcohols. Other transformations are
identifiable to a skilled person upon a reading of the present
disclosure (see, for example, US 2010/0181257 and US 2011/0315636
each incorporated by reference in its entirety). In some
embodiments, the chemical transformation of the reactive site on
the dendritic component can be performed before the dendritic
component is associated with the polymeric component as herein
described. In other embodiments, the chemical transformation of the
reactive site on the dendritic component can be performed after the
dendritic component is associated with the polymeric component as
herein described.
[0232] In particular, in some embodiments where dendrimer particles
are formed in situ, the dendrimer particles can be functionalized
when the particles are formed in the polymer blend and before
casting of the membrane. In other embodiments where dendritic
nanoparticles are formed in situ, the dendritic nanoparticles can
be functionalized after the casting of the membranes, for example
by contacting the membrane with the functionalization reagents to
functionalize the nanoparticles and then rinsing the membrane. For
example, if a cation-rejecting membrane with a cation-rejecting
nanoparticle concentration of greater than about 20 wt % is
desired, polymeric nanoparticles with amine groups can be formed in
situ in the dope and the particles quaternized using an alkyl
iodide or bromide (see, e.g. FIG. 49 and Example 15 of related
application U.S. Ser. No. 13/754,883 published as US20130213881) by
treating the dope with the alkyl iodide or bromide, casting the
membrane and rinsing the membrane to produce a cation-rejecting
membrane with a nanoparticle concentration of greater than about 20
wt %. If a cation-rejecting membrane with a cation-rejecting
nanoparticle concentration of between about 1 and about 10 wt % is
desired, PAMAM nanoparticles or other polymeric nanoparticles with
amine groups can be formed ex situ (see, e.g., Example 14 of
related application U.S. Ser. No. 13/754,883 published as
US20130213881) and quaternized using an alkyl iodide or bromide
(see, e.g. FIG. 49 and Example 15 of related application U.S. Ser.
No. 13/754,883 published as US20130213881) and then mixed with the
polymer to form the polymer matrix to form a dope for casting a
membrane with a cation-rejecting nanoparticle concentration of
between about 1 and about 10 wt % (see. e.g. Examples 3 and 19). As
another example, if a cation-selective membrane with a
cation-selective nanoparticle concentration of greater than about
20 wt % is desired, PAMAM nanoparticles or other polymeric
nanoparticles with amine groups can be formed in situ in the dope
and the particles functionalized with N, O, and S donors (see,
e.g., Example 17 and FIG. 51 of related application U.S. Ser. No.
13/754,883 published as US20130213881).
[0233] In particular, in some embodiments, the cross-linking of
polymers in the polymer blend herein described to form polymeric
nanoparticles as described herein can result in the formation of
additional reactive sites in addition to those already present on
the polymer forming the polymeric nanoparticle. For example, if the
polymer comprises carboxylic acids groups (e.g., as in
poly(methacrylic acid) or MPA) and the cross-linker used is a
diamine, the cross-linking can give rise to amide reactive sites in
addition to the carboxylic acid reactive sites.
[0234] In some embodiments reactive sites can be introduced in the
polymeric particles post membrane formation e.g., as described in
related application U.S. Ser. No. 13/754,883 published as
US20130213881
[0235] In embodiments herein described of filtration membrane
herein described the reactive site can be selected and configured
on the polymer forming the polymeric nanoparticles of the matrix to
provide selective filtration of one or more chemicals of interest.
In particular, in some embodiments, the reactive site can be
selected to separate the one or more chemicals of interest in the
rejection stream, permeate stream and/or retentate of the membrane.
In particular, the dimension, chemical nature, and electrical
charge of the reactive site as well as the location on the
dendrimer component can be selected based on the dimensions,
chemical nature and electrical charge of the chemical to be
selectively filtered.
[0236] For example, in embodiments wherein selective filtration is
desired to include anions in rejection stream and 2s metal ions
cations such as Ca.sup.2+ and Mg.sup.2+ in the retentate of the
membrane, reactive sites having negatively charged O donors [3] can
be presented on the dendrimer component of the membrane. As another
example, polymeric nanoparticles having neutral oxygen donors can
be used to coordinate selective retention of is metal ions such as
Na.sup.+ [3]. As another example, polymeric nanoparticles, and in
particular dendritic nanoparticles having positively charged
nitrogen atoms (e.g. quaternary ammonium groups) can be used to
selectively reject cations. As another example, polymeric
nanoparticles, and in particular dendritic nanoparticles,
comprising vicinal diol groups can be used to coordinate selective
retention of boron.
[0237] In some embodiments, reactive sites retaining one or more
chemical of interest can then be subjected to further reactions to
selectively release some or all of the chemicals forming the
retentate in a permeate stream, and/or to further modify the
retentate as will be understood by a skilled person upon reading of
the present disclosure.
[0238] In particular, membranes herein described including a
suitable retentate can be treated to convert the retentate into a
catalyst thus forming a catalytic membrane. For example, in some
embodiments, a retentate form by metals can be treated with
suitable active agents to change the oxidation state and/or
ligation state to convert the metal to a catalytically active form.
For example, in an embodiment dendritic components having groups
capable of retention of palladium (e.g. amines and phosphines) can
be subjected to reduction (e.g. H.sub.2 or other reducing agents)
to reduce the Pd atoms to produce catalytically active Pd(0) sites.
Additional suitable metals or other materials suitable for
preparation of catalytic membrane and related activating agents
and/or suitable treatments will be identifiable by a skilled
person.
[0239] In some embodiments, the retentate can be subjected to a
selective release before or after an additional treatment. For
example dendritic components having negatively charged O donors and
tertiary amine groups can be used to selectively bind Ca.sup.2+ and
Mg.sup.2+ ions at pH .about.7.0, and the ions can later be released
from the dendritic component by washing the dendritic component
with an acidic solution containing a small ligand such as citric
acid.
[0240] In some embodiments, the polymeric nanoparticles of the
membranes herein described in any configuration, can be formed by
polymeric nanomaterials according to the present disclosure that
can range from approximately 1-3000 nm in size and can in some
embodiments can selectively encapsulate and release a broad range
of solutes in water including but not limited to cations (e.g.,
copper, silver, gold and uranium), anions (e.g., chloride,
perchlorate and nitrate) and organic compounds (e.g.,
pharmaceuticals) [16, 17].
[0241] In particular in some embodiments, the branched dendritic
molecule forming the dendrimer particles can comprise branched
macromolecules, water-soluble branched molecules with functional N
groups including for example, Gx-NH, PPI dendrimers and Gx-NH.sub.2
PAMAM dendrimers, where x is less than 2. Similarly, polymers such
as polysulfone (PS), polyethersulfone (PES), and/or poly(vinyl)
alcohol can be used in making polymer matrix of the filtration
membranes described herein.
[0242] In some embodiments, the dendrimer particles can be selected
to retain chemicals and to be used as nanoscale reactors and
catalysts [16, 17]. In some embodiments, dendritic nanomaterial can
be selected to be selective for cells, or other biological material
(e.g. to reject or retain such material). For example, in some
embodiments, filtration membranes herein described can be
configured to bind bacteria and viruses possibly followed by a
deactivation of the same [17]. In other embodiments, the dendritic
nanomaterials can be used as scaffolds and templates for the
preparation of metal-bearing nanoparticles with controllable
electronic, optical and catalytic properties [16, 17]. Dendritic
nanomaterials can also be used as delivery vehicles or scaffolds,
for example for bioactive compounds [18].
[0243] According to embodiments herein described, the dendrimer
particles can be functionalized with surface groups can make the
polymeric nanomaterial soluble in selected media or bind to
surfaces. According to some embodiments, a first dendritic
nanomaterial can be covalently linked to one or more further
dendritic nanomaterials or associated with one or more
macromolecules to form supramolecular assemblies.
[0244] According to some embodiments, a polymeric nanomaterial can
be used as functional materials, for example, for water treatment
[19-24]. According to some embodiments, the dendritic component
comprises a carbon based structure functionalized with N or O. In
particular, in some embodiments, the dendritic molecule comprise
amines, carbonyls, and/or amides. In these embodiments, the N and O
groups can sorb anions and/or cations. Exemplary dendritic
components with N and O groups which can function as anion and
cation sorbents include but is not limited to poly(amidoamine)
[PAMAM], poly(propyleneimine) and bis (methylol) propionic acid
(MPA) dendrimers (see, e.g. FIG. 25 of related application U.S.
Ser. No. 13/754,883 published as US20130213881). Syntheses of
dendritic nanomaterials according to the present disclosure can be
carried out, for example, by cross linking of branched dendritic
molecules to form dendrimer-like nano- and/or microparticles.
Further syntheses of dendritic nanomaterials will be apparent to a
skilled person upon reading of the present disclosure (see, for
example, [19-28]).
[0245] According to some embodiments, the dendrimer particles can
bind and release cations such as Cu.sup.2+, Co.sup.2+, Fe.sup.3+,
Ni.sup.2+ and U.sup.6+] and anions such as Cl.sup.-,
ClO.sub.4.sup.- and SO.sub.4.sup.2-, for example, through a change
of solution pH [19-24]. In particular PAMAM, PPI, and MPA particles
can in some embodiments bind and release cations such as Cu.sup.2+,
Co.sup.2+, Fe.sup.3+, Ni.sup.2+ and U.sup.6+, and anions such as
Cl.sup.- ClO.sub.4.sup.- and SO.sub.4.sup.2-. In some embodiments,
low generation PAMAM dendrimers are used and the dendrimer can
present for example, an amide, a primary amine, a secondary amine,
and/or a tertiary amine group. In some embodiments PPI dendrimers
are used. In embodiments where low generation PPI dendrimers are
used, the PPI dendrimers have only primary and tertiary amine
groups. In some embodiments, low generation MPA dendrimers are
used. MPA dendrimers can have carbonyl and/or carboxyl groups which
can allow for membranes to have a high capacity, selective, and/or
recyclable ligands for Ca.sup.2+, Mg.sup.2+ and Na.sup.+ [3].
[0246] According to further embodiments, the dendrimer particles
according to the present disclosure can be functionalized with
terminal groups which can allow them to be soluble in a particular
solvent to type of solvent, bind onto one or more targeted
surfaces, or cross-link with other dendrimers to form
multifunctional supramolecular assemblies [16, 17](See e.g. FIG. 24
of related application U.S. Ser. No. 13/754,883 published as
US20130213881).
[0247] In some embodiments, the dendrimer-like polymeric
nanomaterials can provide selective and recyclable high capacity
macroligands for anions (for example Cl.sup.-, Br.sup.-;
SO.sub.4.sup.2-; NO.sub.3.sup.-; and ClO.sub.4.sup.-) and cations
(for example, Na.sup.+, Ca.sup.2+, and Mg.sup.2+) in aqueous
solutions [21-24]. Such dendritic macromolecules can be suitable,
for example, in making filtration membranes for water purification
as Na.sup.+, Ca.sup.2+, and Mg.sup.2+ cations and anions Cl.sup.-
and SO.sub.4.sup.2- anions make-up more than 98% of the total
dissolved solids (TDS) in brackish water and seawater [29].
[0248] In some embodiments, the dendrimer-like polymeric
nanomaterial are capable of rejecting cations and anions. For
example, dendritic components having negatively charged O donors
can be used to coordinate 2s metal ions such as Ca.sup.2+ and
Mg.sup.2+ [3]. As another example, dendritic components having
neutral oxygen donors can be used to coordinate with Is metal ions
such as Na.sup.+ [3].
[0249] In some embodiments, dendrimer-like polymeric nanomaterials
containing negatively charged O donors and tertiary amine groups
can be used to selectively bind Ca.sup.2+ and Mg.sup.2+ ions at pH
.about.7.0. The Ca.sup.2+ and Mg.sup.2+ ions can then be released
from the dendritic component by washing the dendritic component
with an acidic solution containing a small ligand such as citric
acid. As another example, dendritic nanomaterials containing
neutral O donors and tertiary amine groups can selectively bind
Na.sup.+ ions at pH .about.7.0. The Na.sup.+ ions can then be
released from the dendritic nanomaterial by washing the dendritic
component with an acidic solution containing a small complexing
ligand such as citric acid. These examples are based on established
trends in coordination chemistry [3] and accordingly other methods
of making and using dendritic components based on such trends as
will be understood by a skilled person, can be implemented without
departing from the scope of the present disclosure.
[0250] In some embodiments, the dendritic nanomaterial can be made
by cross-linking branched low-generation dendritic molecules by
using a cross linking agent. For example, a dendritic nanomaterial
comprising amine groups can be combined with a cross linking agent
which is capable of cross linking proximate amine groups
(amine-amine cross linking agents). The amine-amine cross linking
agents can be bifunctional (e.g. two sites which can form covalent
bonds with amines) or multifunctional (e.g. three or more sites
which can form covalent bonds with amines). The cross linking
agents can include but are not limited to primary bifunctionalized
alkanes having the general formula (XXV) or (XXVI) below:
##STR00048##
wherein X.sup.1 and X.sup.2, by way of example, can be
independently selected from (COCl, COBr, COI, Cl, Br, I,
OSO.sub.3CH.sub.3, OSO.sub.3C.sub.7H.sub.7, n can range from 1-15,
and wherein R can be H, alkyl, or epoxy substituted alkyl.
Crosslinking agents can also include imidoesters (e.g. dimethyl
adipimidate.2HCl (DMA), dimethyl pimelimidate.2HCl (DMP), dimethyl
suberimidate.2HCl (DMS), dimethyl 3,3'-dithiobispropionimidate.2HCl
(DTBP)), N-hydroxy succinimide (NHS)-esters (e.g. disuccinimidyl
suberate (DSS), bis(sulfosuccinimidyl) suberate (BS3),
disuccinimidyl glutarate (DSG)), and
1,5-difluoro-2,4-dinitrobenzene (DFDNB). Exemplary amine cross
linking agents comprise in particular, trimesoyl chloride (TMC),
1,3-dibromopropane (DBP), and epichlorohydrin (EPC) to form
dendritic nanoparticles.
[0251] In some embodiments, membranes can be fabricated by casting
a mixture of the polymer component, the dendritic component, one or
more solvents, and a cross-linking agent onto porous polymeric MF
membrane supports [30].
[0252] Targeted atomistic molecular dynamics (MD) simulations of
anion and/or cation binding to a dendritic component (e.g. PAMAM,
PPI, and MPA) can be carried out using a Dreiding III force field
(FIG. 26 of related application U.S. Ser. No. 13/754,883 published
as US20130213881) [13] to develop and validate a computer-aided
molecular design framework that can be used to guide the synthesis
of high capacity and recycle low-cost ion-selective dendritic
polymers.
[0253] In some embodiments, the membranes with embedded
nanoparticles as described herein can comprise a polymeric matrix
with dendrimer particles made from cross-linked linear polymers. In
some embodiments, the membranes with embedded nanoparticles as
described herein can comprise a polymeric matrix made from
poly(vinylidene) fluoride (PVDF) with polymeric nanoparticles made
from cross-linked linear polymers (e.g. polyamine). In some
embodiments, the membranes with embedded nanoparticles as described
herein can comprise a polymeric matrix made from poly(vinylidene)
fluoride (PVDF) with polymeric nanoparticles made from cross-linked
low generation dendrimers such as Poly(amidoamine) (PAMAM)
dendrimers, poly(propyleneimine) [PPI] dendrimers,
2,2-bis(methylol)propionic acid (bis-MPA) dendrimers, 2
cyclotriphosphazene-phenoxymethyl(methylhydrazono) (PMMH)
dendrimers and other low-generation dendrimers of various core
chemistry and terminal groups.
[0254] In some embodiments, the mixed matrix membrane with embedded
dendrimer particles and related compositions and methods described
herein can be used to provide a fast and scalable route for the
preparation of high capacity membrane absorbers for the selective
extraction and recovery metals from aqueous solutions. In
particular, these mixed matrix membranes can be used as membrane
absorbers or sorbents for the selective recovery of dissolved
metals such as Cu(II) or Pt(II) or metal particles (Cu(0) or Pt(0)
from industrial liquid waste stream using low-pressure membrane
filtration.
[0255] The term "membrane absorbers" used herein refer to a type of
membranes capable of functionalizing as a sorbent to selectively
absorb substances, materials or chemical compounds due to their
high affinity of doing so. In particular, the membrane absorbers
described herein have strong binding affinity for target substances
and/or chemical compounds but allow others to pass through the
membrane absorbers.
[0256] One of the challenges in metal recovery from industrial
wastewater is to design and synthesize high capacity, recyclable
and robust chelating ligands with tunable metal ion selectivity
that can be efficiently processed into low-energy separation
materials and systems (e.g. ultrafiltration membrane absorbers and
modules).
[0257] For example, in aqueous solutions and industrial wastewater,
dissolved Cu is predominantly found as cationic species..sup.14,24
Chelating agents are the most effective ligands for recovering
cationic species from aqueous solutions. Metal ion complexation is
an acid-base reaction that depends on several parameters including
(i) ion size and acidity, (ii) ligand basicity and molecular
architecture and (iii) solution physical-chemical
conditions..sup.24
[0258] Membrane absorbers made from high generation dendrimers
(e.g. G4-G5 NH.sub.2 PAMAM) have shown to possess high capacity,
selective and recyclable macroligands for metal recovery from
aqueous solutions using dendrimer enhanced filtration (DEF) process
and dendronized PAMAM hollow fiber membranes (reference 26).
However, these membrane absorbers are expensive to produce due to
the large number of synthetic and purification steps required
preparing such macromolecules.
[0259] In some embodiments, the membrane absorbers described herein
comprising the embedded dendrimer particles formed from low
generation dendrimers (e.g. G0-G3 PAMAM dendrimers) herein
described possess high metal ion chelating capability and behave
similarly as membrane absorbers formed from high generation
dendrimers (e.g. G4-6 PAMAM). In particular, the membrane absorbers
synthesized from G0-G3 dendrimers exhibit the container properties
of G4-G6 dendrimers for containing metal ions.
[0260] In some embodiments, the membrane absorbers described herein
can serve as supramolecular contains, also referred to as
"supercontainers" for containing cations, anions, organic solutes,
bioactive molecules and catalytic and redox active
metallic/bimetallic nanoparticles and cluster.
[0261] The membrane absorbers can be utilized as templates for
preparation of dendrimer-encapsulated nanoparticles (DENs) with
tunable electronic, optical and catalytic properties. The membrane
absorbers described herein with in-situ synthesized dendrimer
particles can also serve as multifunctional membranes for a variety
of SusChEM related applications including (i) water treatment, (ii)
metal extraction and recovery, (iii) biochemical separations and
purifications and (ii) catalysis and reaction engineering.
[0262] In some embodiments, the method of using the membrane
absorbers as a supercontainer comprises preparing a mixed matrix
membrane with embedded dendrimer particles, providing a sample
solution to be filtrated, such as a sample solution containing
metal ions, pumping the solution through the mixed matrix membrane
to yield a permeated sample, and collecting the permeated sample.
The pumping and collecting steps can be repeated until a desired
filtered sample is obtained. The sample solution herein used refers
to a solution to be filtered. Such solution can be industrial waste
water or aqueous solution or any solution containing chemical
compounds that aim to be removed from the solution (see Example
4.). In some embodiments, the membrane absorbers are mixed matrix
membrane comprising a polymeric matrix made with poly(vinylidene)
fluoride (PVDF) embedded with in situ synthesized dendrimer
particles formed by G0 or G1 or G2 PAMAM dendrimers.
[0263] In some exemplary embodiments (see Examples 7-8), the
membrane absorbers comprising embedded dendrimer particles formed
by G1 PAMAM dendrimers (MDP-G1 membrane absorbers) are capable of
binding copper at an amount greater than that of the membrane
absorbers made from G0 PAMAM dendrimers (MDP-G0 membrane
absorbers).
[0264] In some of these embodiments, the MDP-G0 membrane absorbers
are capable of binding copper with a mean percentage of bound
copper of about 25% or less with an averaged binding capacity of
about 46-52 mg of Cu (II) per mL of dry membrane. The MDP-G1
membrane absorbers are capable of binding copper with a mean
percentage of bound copper of larger than 50%, more particularly,
larger than 70%, more particularly, larger than 80%, with an
averaged binding capacity of about 51-57 mg of Cu(II) per mL of dry
membrane, depending on the pH value of the aqueous solution (see
Example 7 and Table 12).
[0265] The MDP-G0 membrane absorbers of some embodiments herein
described can bind an amount of Cu(II) (for example, 19-21
g/m.sup.2 of dry membrane) higher than those of a crosslinked PVA
membrane with embedded PEI networks [31] (.about.11 g/m.sup.2 of
dry membrane) and HPAMAM surface-grafted PET membrane (1.42
g/m.sup.2 of dry membrane) [32] (see Examples 5-8). In some of
these embodiments, the MDP-G0 membrane absorber has a high water
flux (.about.427.+-.13 LMH at 2 bar and pH 7) with a neutral
surface layer and a matrix with a sponge-like microstructure
characteristic of UF membranes with strong mechanical integrity
(see Examples 7-8).
[0266] The membrane absorbers herein described can bind transition
metals such as Cu(II). Cu(0) and Pt(0) through several mechanism
including (i) coordination with their N and O donors and (ii)
non-specific binding to water molecules and/or couterions trapped
inside the dendrimer particles. In particular, Cu(II) can form
complexes via different copper coordination sites within the
embedded dendrimer-like particles through nitrogen donors, oxygen
donors and water molecules (see Example 8 and FIG. 38).
[0267] Further investigation can be conducted to optimize the
performance, such as sorption capacity and regeneration efficiency,
of the membrane absorbers with in situ synthesized dendrimer
particles made from low-generation dendrimers for the metal
recovery from relevant industrial liquid waste streams.
[0268] According to a further embodiment of the disclosure, a
method of making a polymeric membrane with embedded dendrimer
particles is described. The method comprises contacting a polymeric
component, a dendritic component, and a solvent to provide a blend,
contacting the blend with a cross-linking component, for a time and
under a condition to permit the in situ formation of dendrimer
particles to provide a dope solution, and casting the dope solution
to provide a filtration membrane with embedded dendritic
nanoparticles (see for example, FIGS. 18A-C and 19A-B).
[0269] In particular, in some embodiments, contacting a polymeric
component, a dendritic component, and a solvent to provide a blend
is performed by mixing a solution of the base polymer of the
polymeric component in a suitable solvent--the suitable solvent
chosen based on parameters such as solubility parameters (see e.g.
[7, 14]), compatibility of the dendritic component with the polymer
component (e.g. hydrogen bonding between amine groups and fluoride
groups or interaction of hydroxyl/carboxylic acid groups with
oxygen atoms), or other chemical and thermodynamic parameters
identifiable to a skilled person--for approximately 1-24 hours at
25-85.degree. C. --or other times and temperatures capable of
producing a homogeneous solution without decomposing the polymeric
component as would be identifiable to a skilled person--and then
adding a solution of the dendritic component and mixing to form a
homogeneous blend (see, e.g., Examples 1 and 2 of related
application U.S. Ser. No. 14/447,574). A functionalizing polymer
presenting a functional group capable to react with a corresponding
group in the dendrimer component can be added into the blend and is
allowed to react for a time depending on the reactivity of the
functional polymer end group (e.g. 1-10 hrs) and preferably between
1 hr or 2 hrs. In particular, in some embodiments, that the
concentration of the dendritic component is between about 3.5 wt %
and 7.5 wt % of the blend. In particular, in some embodiments, the
contacting of the blend with a cross linking component can be
performed by mixing a crosslinking catalyst and cross-linking
component--the cross-linking catalyst and cross linking component
chosen based on the functional groups on the dendritic component as
would be identifiable to a skilled person (e.g., if the dendritic
component has amine groups, the cross linking component can be an
epoxide such as epichlorohydrin or dihaloalkane such as
1,3-dibromopropane and the catalysts can be HCl; if the dendritic
component has carboxylic acid groups, the cross-linking component
can be a diamine such as 1,3-diamino propane and the cross-linking
catalyst can be 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide)
(EDC))--for 1-24 hours at approximately 25-85.degree. C. --or other
times and temperatures capable of producing a homogeneous dope
without decomposing either the polymeric or dendritic components as
would be identifiable to a skilled person--to provide a dope
solution with dendrimer particles formed in situ (see, e.g.,
Examples 1 and 2 of related application U.S. Ser. No.
14/447,574).
[0270] In particular, in membranes cast with in situ generated
nanoparticles, aggregates and clusters of nanoparticles that form
for example through fractal growth are not detectable contrary to
membranes cast with nanoparticles that are preformed (compare,
e.g., FIG. 6 of the related application U.S. Ser. No. 14/447,574
and FIG. 6 of related application U.S. Ser. No. 13/754,883
published as US20130213881 with FIG. 53 and FIG. 58B of related
application U.S. Ser. No. 13/754,883 published as US20130213881)
resulting in discrete nanoparticles being distributed in membranes
with nanoparticles formed in situ. In particular, in some
embodiments, the nanoparticles can be present in the membrane at a
concentration of greater than about 20 wt %, and more particularly
at a concentration of greater than about 35% and from 50% to
60%.
[0271] In particular, in some embodiments, the dope solution with m
situ formed dendrimer particles can be cast to provide a polymeric
membrane with embedded with dendrimer particles. In particular, in
some embodiments, the membrane can be cast by phase inversion
casting (see, e.g. [12]). In particular, in some embodiments, the
casting can be performed by pouring the hot dope solution onto a
glass surface and allowing it to air dry at room temperature and
then immersing it into water for a time to form a nascent membrane
as would be identifiable to a skilled person. The nascent membrane
can then be immersed in fresh water and then immersed in ethanol to
remove impurities as would be identifiable to a skilled person. The
membranes can then be removed from the glass and dried to provide a
polymeric membrane with pores, the pores embedded with dendritic
nanoparticles. In other embodiments, the dope solution with in situ
formed dendrimer particles can be cast onto a polymer support (e.g.
a poly(ethylene terephthalate) non-woven fabric) in place of glass
to provide a polymeric membrane with pores, the pores embedded with
dendritic nanoparticles wherein the polymeric membrane is layered
on top of the polymer support.
[0272] FIGS. 19A-B show an exemplary embodiment of procedures and
reaction schemes used to prepare mixed matrix PVDF membranes with
in situ synthesized PAMAM particles. The preparation procedures
illustrated in FIG. 19A includes (i) preparation of membrane
casting solution by dissolution of PVDF in TEP, (ii) addition of
PAMAM and ECH to the membrane casting solution to initiate the in
situ crosslinking reactions between PAMAM and ECH, (iii) membrane
preparation by phase inversion casting. FIG. 19B illustrates the
reaction schemes: (i) reaction of ECH epoxy groups with the primary
amino groups of the segregated PAMAM macromolecules in the dope
solution via ring opening nucleophilic substitution followed by the
nucleophilic displacement of the ECH chloro groups via reaction
with the remaining primary/secondary amino groups of the PAMAM
macromolecules.
[0273] According to further embodiments, a method of making a
polymeric membrane with embedded preformed dendrimer particles is
described. The method comprises contacting a polymeric component,
preformed dendrimer particles, and a solvent for a time and under a
condition to provide a dope solution; and casting the dope solution
to provide a polymeric membrane with pores, the pores embedded with
the preformed polymeric nanoparticles.
[0274] In particular, in some embodiments, the preformed dendrimer
particles can be performed by cross-linking a polymer (e.g. G0 or
G1 PAMAM with terminal primary amine (--NH_2) groups) using a
crosslinker such as ECH by adapting the inverse suspension process
that Diallo and co-workers used to prepare PEI beads. [33] The
methods described in this paper are incorporated by reference in
its entirety.
[0275] In some embodiments, G0 to G3 low generation dendrimers are
in contact with a crosslinker in a two phase suspension to form
preformed dendrimer particles. In some embodiments, the preformed
dendrimer particle can be subsequently reacted with a
functionalizing agent such as an alkylating reagent to provide
functionalized dendrimer particle. In some embodiments, the
functionalized dendrimer particle contains a quaternary ammonium
group.
[0276] In some embodiments, the alkylating reagent can be selected
from a group consisting of bromoethane, iodomethane,
1-bromopropane, 1-bromo-2-methylpropane, 1-bromobutane or a
combination thereof.
[0277] In particular, G0 to G3 low generation dendrimers are
dissolved in water. The aqueous solution containing G0 to G3 low
generation dendrimers is in contact with an organic solvent under a
condition to form an inverse suspension having aqueous solution
particle of dendrimer suspended in the organic solvent. A
crosslinker is provided and in contact with the inverse suspension
for a sufficient interval of time under a condition suitable for
the reaction of the crosslinker and the dendrimer in the aqueous
solution particle to occur, thus forming preformed dendrimer
particles. In particular, in some embodiments, contacting a
polymeric component, preformed polymeric nanoparticles, and a
solvent for a time and under a condition to provide a dope solution
is performed by mixing a solution of the polymeric component in the
solvent for 1-24 hours at approximately 25-85.degree. C. --or other
times and temperatures capable of producing a homogeneous solution
without decomposing the polymeric component as would be
identifiable to a skilled person--and then adding a solution of the
preformed dendrimer particles and mixing the solution for 1-24
hours at approximately 25-85.degree. C. --or other times and
temperatures capable of producing a homogeneous blend without
decomposing either the polymeric or dendritic components as would
be identifiable to a skilled person to provide a dope solution with
preformed dendrimer particles.
[0278] In particular, in some embodiments, the dope solution with
preformed dendrimer particles can be cast to provide a polymeric
membrane with embedded with dendritic nanoparticles. In particular,
in some embodiments, the membrane can be cast by phase inversion
casting (see, e.g. [12]). In particular, in some embodiments, the
casting can be performed by pouring the hot dope solution onto a
glass surface and allowing it to air dry at room and then immersing
it into water for a time to form a nascent membrane as would be
identifiable to a skilled person. The nascent membrane is then
immersed in fresh water and then immersed in ethanol to remove
impurities as would be identifiable to a skilled person. The
membranes can then be removed from the glass and dried to provide a
polymeric membrane with pores, the pores embedded with dendritic
nanoparticles. In other embodiments, the dope solution with
preformed dendritic nanoparticles can be cast onto a polymer
support (e.g. a poly(ethylene terephthalate) non-woven fabric) in
place of glass to provide a polymeric membrane with pores, the
pores embedded with dendritic nanoparticles wherein the polymeric
membrane is layered on top of the polymer support.
[0279] In particular, membranes cast with preformed nanoparticles
can possess aggregates and clusters of nanoparticles that form
through fractal growth unlike the discrete particles embedded in
membranes when the particles are formed in situ (compare, e.g.,
FIG. 53 and FIG. 58B of related application U.S. Ser. No.
13/754,883 published as US20130213881 with FIG. 6 of the related
application U.S. Ser. No. 14/447,574 and FIG. 6 of related
application U.S. Ser. No. 13/754,883 published as
US20130213881).
[0280] In some embodiments, the membranes with embedded
nanoparticles as described herein can comprise a polymeric matrix
made from poly(vinylidene) fluoride (PVDF) as a base polymer, and
epoxy polyethylene glycol as a functionalizing polymer with
polymeric nanoparticles made from cross-linked poly(methacrylic
acid) (PMAA). In particular, when the particles are premade, the
PMMA can be cross-linked with either EGDMA or PEGDMA with an AIBN
initiator (see, e.g., Example 14 related application U.S. Ser. No.
13/754,883 published as US20130213881).
[0281] In some embodiments, the membranes with embedded dendrimer
particles as described herein can comprise a polymeric matrix made
from poly(vinylidene) fluoride (PVDF) as a base polymer with
dendrimer particles made from cross-linked PAMAM. In particular,
when the particles are premade, the PAMAM can be cross-linked with
ECH (see, e.g., Examples 2 and 5).
[0282] In some embodiments, a dope comprising a polymer forming the
polymer matrix herein described in which dendrimer particles is
embedded can be used to provide nanofibers and/or microfibers.
[0283] The term "fiber" as used herein indicates a material that is
a continuous filament or is in a discrete elongated piece, similar
to a length of thread. In particular, "nanofiber" as used herein
refer to fibers with a diameter less than approximately 1000 nm and
the term "microfiber" as used herein refer to fibers with a
diameter between approximately 1 .mu.m to approximately 10 .mu.m in
size.
[0284] In particular, in some embodiments the dope solution
comprising a polymer embedding dendrimer particles dendrimer
particles and/or nanoparticles herein described can be used in a
method of making a nano and/or micro fibers with embedded
dendrimer-like polymer nanoparticles herein described.
[0285] In some embodiments, the method comprises contacting a
polymeric component, a dendritic component, a cross-linking
component, and a solvent for a time and under a condition to permit
the in situ formation of dendritic nanoparticles to provide a dope
solution; and spinning the dope solution to provide a nanofiber or
microfiber herein described. In particular, in some embodiments,
the polymeric component and dendritic component are contacted to
form a blend and the cross-linking agent is added to the blend to
allow in situ formation of dendritic nanoparticles and obtain the
dope before the spinning. In some embodiments, the nanoparticle are
preformed and then added to the polymer for an ex situ formation
according to methods and systems herein described to provide a dope
solution that is then spun to provide a nano-fiber and/or
microfiber herein described.
[0286] In some embodiments, the nanofibers with embedded polymeric
nanoparticles can be electrospun onto a support layer (e.g. a PET
non-woven fabric: see e.g. Example 2 of U.S. Ser. No. 14/447,574).
Then a nanofibrous composite membrane can be fabricated as
described in U.S. patent application Ser. No. 13/570,221 entitled
"Filtration Membranes, and Related Nano and/or Micro fibers,
Composites, Methods and Systems" filed on Aug. 8, 2012 with
attorney docket P1069-US incorporated by reference in its
entirety.
[0287] A "support layer" in the sense of the present disclosure is
an aggregate material comprising a polymer component configured to
strengthen the membrane structure. Suitable polymers to be included
in support layers comprise, for example, poly(vinylidene) fluoride
(PVDF), poly(tetrafluoroethylene) (PTFE), poly(acrylonitrile)
(PAN), poly(methyl methacrylate) (PMMA), poly(methacrylic acid)
(PMAA), poly(acrylic acid) (PAA), poly(vinyl methyl ketone), and
poly(ethylene terephthalate) (PET) which can be aggregated by
inverse casting the polymer or by electrospinning. In some
embodiments the support layer includes pores. In some embodiments,
the support layer can be functionalized with a dendrimer component.
In other embodiments, after a nanofibers and/or microfibers with
embedded dendritic nanoparticles are electrospun onto a support
layer, a further support layer can be electrospun to provide a top
support layer for providing additional strength or for creating a
bipolar membrane. In some embodiments, the support layer can
comprise or be formed by a polymer matrix with embedded
dendrimer-like polymer nanoparticles, and in particular dendritic
nanoparticles, in accordance with the present disclosure.
[0288] Accordingly, in some embodiments a filtration membrane can
comprise a plurality of nano and/or micro fibers, wherein at least
one of the nano and/or micro fibers comprises polymeric
nanoparticles embedded in a polymeric component. The plurality of
nano and/or micro fibers can be attached to a support layer and/or
a polymer matrix comprising embedded polymer nanoparticles and in
particular dendritic nanoparticles herein described. Additional
layers such as a separation layer or a further support layer can
also be comprised as will be understood by a skilled person.
[0289] In some embodiments a filtration membrane can comprise a
polymer matrix comprising embedded dendrimer particles and/or
nanoparticles herein described attaching a nano- and/or microfiber.
Additional layers such as a separation layer or a further support
layer can also be comprised as will be understood by a skilled
person.
[0290] In some embodiments, the nanofiber and/or microfiber can
comprise a polymeric nanoparticle embedded in a polymeric component
as described herein. In some embodiments other kind of nanofibers
and/or microfibers can be comprised in filtration membranes herein
described in the alternative or in addition to a nano fiber and/or
microfiber with embedded nanoparticles. In particular in some of
those embodiments, another kind of nano-fiber and/or microfiber
that can be comprised in a filtration membrane herein described can
comprise a scaffold component providing a supporting framework for
one or more additional components attached to the scaffold
providing functionalities to the scaffold and in particular to a
dendrimer component as described in U.S. patent application Ser.
No. 13/570,221, published as US20130112618 incorporated by
reference in its entirety. The scaffold component and the
additional components define features of the nanofiber and
microfiber such as a diameter (or radius), a mechanical strength,
chemical stability, functionalization and chemical properties which
are detectable using techniques and process identifiable by a
skilled person. Additional details concerning the nano-fiber and/or
microfiber comprising a scaffold component and a dendrimer
component are described in U.S. patent application Ser. No.
13/570,221 published as US 21013 0112618 incorporated by reference
in its entirety.
[0291] In some embodiments the dendrimer particles embedded in the
polymeric component of the nanofiber or microfiber and/or presented
on the scaffold component of the nano-micro-fiber can comprise
reactive sites, and the reactive sites can be positively and/or
negatively charged.
[0292] In some embodiments, in the filtration membrane, the
plurality of nanofibers and/or microfibers can be arranged in a
mesh structure forming a layer comprised in the membrane, alone or
in combination with additional layers. In some embodiments, the
plurality of nanofibers and/or microfibers are arranged in a
substantially parallel configuration, in particular in some of
these embodiments, one or more nanofibers and/or microfibers of the
plurality of the nanofibers and/or microfibers are hollow.
[0293] In particular, in some embodiments microfiber and/or
nanofiber herein described can be comprised as a composite material
layer having a mesh structure comprised in the filtration membrane
alone or in combination with one or more additional layers.
[0294] The term "composite material" as used herein refers to a
heterogeneous material made from two or more different materials,
the materials having different chemical and/or physical properties
and remaining as separate and distinct materials within the
composite material. For example, according to embodiments herein
described, a composite material can comprise a polymer component
and a dendritic nanoparticle which is structurally different from
the polymer component and is embedded in the polymer component. The
composite material according to some embodiments can comprise a
semi-permeable barrier made of overlapping strands of
nanofibers.
[0295] In particular, the composite material comprising a plurality
of nanofibers and/or microfibers can comprise a plurality of a same
type of fiber or of two or more different types of fibers. In some
embodiments, fibers can be covalently cross-linked to one another.
In some embodiments, nanofibers and/or microfibers comprised in the
composite material can comprise hollow fibers herein described.
[0296] In embodiments herein described, wherein a membrane comprise
a mesh, the features of the mesh such as dimension of the pores of
the mesh structure, the strength and resistance of the mesh and
chemical compatibility of the mesh can be controlled by selection
of the diameter of the nanofiber or microfiber, number and
configuration of the nanofiber and/or microfiber forming the mesh
and the specific polymer component and dendrimer component of each
fiber as will be understood by a skilled person upon reading of the
present disclosure.
[0297] Also described herein is a bicomposite membrane, which
comprises a plurality of nanofibers and/or microfibers herein
described attached to a polymer matrix formed by a porous polymeric
aggregate comprising dendrimer particles. In particular, in some
embodiments, the polymeric nanoparticles are embedded in the porous
polymer aggregate (e.g., by in situ particle formation as herein
described).
[0298] In particular, in some embodiments, the nanofibers and/or
microfibers in the bicomposite membrane can comprise dendritic
nanoparticles embedded (e.g. through in situ particle formation as
herein described) in a polymer matrix as described herein. In some
embodiments, the nanofibers and microfibers comprising embedded
nanoparticles can be hollow. In some embodiments the polymeric
nanoparticles embedded in the polymeric component of the nanofiber
or microfiber comprises reactive sites, and the reactive sites can
be positively and/or negatively charged.
[0299] In particular, in some embodiments, the nanofibers and/or
microfibers in the bicomposite membrane comprise a scaffold
component providing a supporting framework for one or more
additional components attached to the scaffold providing
functionalities to the scaffold. The scaffold component and the
additional components define features of the nanofiber and
microfiber such as a diameter (or radius), a mechanical strength,
chemical stability, functionalization and chemical properties which
are detectable using techniques and process identifiable by a
skilled person. The features of nanofibers and microfibers in the
sense of the present disclosure which can also be controlled by
modifying the chemical composition and structure of the fiber
during manufacturing of the fiber according to techniques
identifiable by a skilled person upon reading of the present
disclosure. In particular, in some embodiments, the scaffold
component comprises a polymeric component providing a fiber
scaffold and the additional component comprises a dendritic
component attached to the polymeric component to present reactive
sites on the fiber scaffold (see, e.g., FIG. 63 of related
application U.S. Ser. No. 13/754,883 published as
US20130213881).
[0300] In some embodiments, in the bicomposite membrane, the
plurality of nanofiber and/or microfiber are arranged in a mesh
structure forming a layer comprised in the membrane, alone or in
combination with additional layers. In some embodiments, the
plurality of nanofiber and/or microfibers are arranged in a
substantially parallel configuration, in particular in some of
these embodiments, one or more nanofibers and/or microfibers of the
plurality of the nanofibers and/or microfibers are hollow.
[0301] In particular, in some embodiments, the plurality of
nanofibers and/or microfibers is directly attached to polymer
matrix formed by a porous polymeric aggregate comprising polymeric
nanoparticles (e.g. by forming a polymer aggregate comprising
polymeric nanoparticles by in situ particle formation as herein
described and electrospinning the nanofibers and/or microfibers
directly only the polymer aggregate comprising polymeric
nanoparticles). In other embodiments, the plurality of nanofibers
and/or microfibers is attached to a support layer (e.g. a PET
non-woven fabric) and the support layer is further attached to
porous polymeric aggregate comprising polymeric nanoparticles (e.g.
by casting a membrane comprising porous polymeric aggregate with
embedded polymeric nanoparticles on a support layer and then
electrospinning the nanofibers and/or microfibers onto the side of
support layer opposite to the membrane comprising porous polymeric
aggregate with embedded polymeric nanoparticles; see e.g. Examples
1 and 2 and for the casting procedure in in situ methods Examples
2, 20 and FIGS. 59 and 60 of related application U.S. Ser. No.
13/754,883 published as US20130213881)
[0302] In some embodiments a filtration membrane comprises a layer
of the composite material according to the disclosure in
combination with one or more additional layers. The additional
layers can include, for example, a support layer and/or a
separation layer (see e.g. Examples 22-24 and FIGS. 62 and 63 of
related application U.S. Ser. No. 13/754,883 published as
US20130213881). In embodiments wherein filtration membrane herein
described comprise one or more composite material layers and one or
more additional layers, the one or more composite material layers
and the additional layers can be comprised in the filtration
membrane in various configurations as will be understood by a
skilled person upon reading of the present disclosure. For example
in some embodiments one or more composite layers can be comprised
between two functionalized or unfunctionalized supporting layers.
In some embodiments, one or more composite layers can be comprised
between a supporting layer and a coating layer. In some of these
embodiments a functionalized supporting layer can be further
attached to the coating layer. In some embodiments a coating layer
can be comprised between one or more composite layers a
functionalized supporting layer. Additional configurations can be
identified by a skilled person. In particular, selection of a
configuration of the membrane can be performed by a skilled person
in view of the polymer component and dendrimer component forming
the composite material and/or the support layer and/or coating
layer and in view of a desired selection of one or more chemicals
to be filtered. (see e.g. U.S. patent application Ser. No.
13/570,221 published as US 2013 0112318)
[0303] In some embodiments, where the filtration membrane comprises
a composites material layer with one or more additional layers, the
polymer component and the dendritic component of the one or more
composite material layers and/or of the one or more additional
layer can be either the same or different. In some of these
embodiments, the polymer component can be polysulfone (PS),
polyether sulfone (PES), poly(vinylidene) fluoride (PVDF),
poly(tetrafluoroethylene) (PTFE), poly(acrylonitrile) (PAN),
poly(methyl methacrylate) (PMMA), poly(methacrylic acid) (PMAA),
poly(acrylic acid) (PAA), and/or poly(vinyl methyl ketone). In some
of these embodiments the dendrimer component can be a dendritic
macromolecule selected from the group consisting of generation-3
poly(amidoamine) (PAMAM) dendrimer, generation-4 poly(amidoamine)
(PAMAM) dendrimer, generation-5 poly(amidoamine) (PAMAM) dendrimer,
generation-3 poly(propyleneimine) (PPI) dendrimer, generation-4
poly(propyleneimine) (PPI) dendrimer, generation-5
poly(propyleneimine) (PPI) dendrimer, generation-3
poly(bis(methylol)propionic acid) (MPA) dendrimer, generation-4
poly(bis(methylol)propionic acid) (MPA) dendrimer, generation-5
poly(bis(methylol)propionic acid) (MPA) dendrimer, generation-3
poly(ethyleneimine) dendrimer, generation-4 poly(ethyleneimine)
dendrimer, generation-5 poly(ethyleneimine) dendrimer, and
hyperbranched poly(ethyleneimine), or aggregate nanostructures
and/or microstructure thereof.
[0304] According to a further embodiment of the disclosure, a
filtration system is described. The filtration system comprises a
plurality of modules, each module comprising one or more of the
filtration membranes for pretreatment of water according to
embodiments herein described, charged particle rejection of water,
and charged particle absorption of water is described.
[0305] The term "module" as used herein refers to a compartment
comprising a filtration membrane according to the disclosure,
adapted to be used in connection with other modules to perform
parallel and/or sequential filtrations.
[0306] In particular, in some embodiments, a module herein
described can comprise one of the filtration membranes herein
described through which water can pass. For example, if the
membrane in a module is charged particle rejecting, it can remove
charged particles from the water passing through the membrane in
the module such that the charged particles are reduced and/or
substantially eliminated from water exiting the membrane. As
another example, if the membrane in a module is charged particle
absorbing, it can absorb charged particles from the water passing
through the membrane in the module such that the charged particles
are reduced or eliminated from water exiting the membrane.
[0307] In some embodiments, the filtration system can be configured
to have three units: a first unit comprising a module, the module
comprising a nanofiltration membrane to remove, for example,
particles and dissolved organic matter; a second unit comprising a
series of alternating positive and negative charged particle
rejecting modules, for example, to remove a majority of the charged
particles; and a third unit comprising a parallel series of modules
capable of absorbing charged particles of interest.
[0308] Also provided herein, a filtration method comprising,
passing water to be filtered through one or more modules comprising
conventional nanofiltration membranes to remove particles and
dissolved organic matter, passing the water through a series of
alternating positive and negative charged particle rejecting
modules comprising the membranes herein described to remove a
majority of the charged particles, and passing the water through a
parallel series of modules capable of absorbing charged particles
of interest is described.
[0309] In some embodiments, the membrane filtration system for the
desalination of brackish water and seawater comprises: an
ion-rejection filtration stage, wherein saline water passes through
a series of alternating cation/anion selective tight UF membranes
designed to reject 70-90% of dissolved ions: and an ion-absorption
filtration stage, wherein the product water from the ion-rejection
filtration system is split into two streams that pass through a
series of ion-absorbing MF membranes designed to selectively bind
target anions/cations of interest.
[0310] In some embodiments, filtration membranes can be used for
microalgae filtration and recovery, and in particular, in
microalgae recovery by ultrafiltration.
[0311] In some embodiments, in particular when one or more
functionalizing polymer are hydrophilic membranes according to the
disclosure can be fouling resistant and high flux membranes with
respect to known conventional membrane. Mixed matrix membranes
(MMMs) with embedded functional nanomaterials/particles can carry
out multiple functions (e.g. retention, sorption, catalysis and
charge transport) with improved properties and performance
including higher permselectivity and flux, greater mechanical
strength and lower fouling propensity in water filtration
applications and in particular in application where harvesting of
microalgae and possibly subsequent downstream processing into a
useful product (e.g. biofuel) is desired.
[0312] Further advantages and characteristics of the present
disclosure will become more apparent hereinafter from the following
detailed disclosure by way or illustration only with reference to
an experimental section.
EXAMPLES
[0313] The polymeric membranes with embedded polymeric
micro/nanoparticles and related methods and systems herein
described are further illustrated in the following examples, which
are provided by way of illustration and are not intended to be
limiting.
[0314] In particular, the following examples illustrate exemplary
polymeric membranes with embedded dendrimer-like polymeric
micro/nanoparticles and related methods and systems. A person
skilled in the art will appreciate the applicability and the
necessary modifications to adapt the features described in detail
in the present section, to additional polymeric membranes with
embedded dendrimer-like polymeric micro/nanoparticles and related
methods and systems according to embodiments of the present
disclosure.
Example 1
Chemicals and Materials
[0315] Polyvinylidene fluoride (PVDF) [Kynar 761] was provided by
Arkema (King of Prussia, Pa., USA). G0-NH.sub.2 and G1-NH.sub.2
PAMAM dendrimers were purchased as methanol solutions (.about.34 wt
%) from Dendritech Inc, USA. Table 6 lists selected
physical-chemical properties of the PAMAM dendrimers.
Epichlorohydrin (ECH) was purchased from Sigma-Aldrich. Triethyl
phosphate (TEP), ethanol and nitric acid (60 wt % HNO.sub.3) were
purchased from Daejung Chemicals (South Korea). Hydrochloric acid
(12 M HCl) was purchased from Junsei (South Korea). Sodium
hydroxide (NaOH pellets) and copper(II) nitrate trihydrate (ACS
purus grade) were purchased from Sigma-Aldrich. A standard solution
of copper (Cu) [10 mg/L in 5 wt % HNO.sub.3](Multi-element
calibration standard-2A) was purchased from Agilent Technologies.
All chemicals were used as received. All aqueous solutions were
prepared using Milli-Q deionized water (DIW) with a resistivity of
18.2M.OMEGA.cm and total organic content <5 ppb.
TABLE-US-00006 TABLE 6 Selected physicochemical properties of the
PAMAM dendrimers that were utilized as particle precursors for the
mixed matrix PVDF membranes with in situ synthesized PAMAM
particles. The data were taken from Dendritech. .sup.aM.sub.wth
.sup.eC.sub.Pamine .sup.fC.sub.Tamine .sup.gC.sub.Amide
.sup.hC.sub.Ligand .sup.iD.sub.H Dendrimer (Dalton)
.sup.bN.sub.Pamine .sup.cN.sub.Tamine .sup.dN.sub.Amide (meq/g)
(meq/g) (meq/g) (meq/g) (nm) G0-NH.sub.2 517 4 2 4 5.56 2.78 5.56
19.47 1.5 G1-NH.sub.2 1430 8 6 12 4.00 3.00 6.00 18.99 2.2
.sup.aM.sub.wth: theoretical molecular weight. .sup.bN.sub.Pamine:
number of primary groups. .sup.cN.sub.Tamine: number of tertiary
amine groups. .sup.dN.sub.Amide: number of amide groups. Each amide
group has 2 potential electron donors: 1 N donor and 1 O donor.
.sup.eC.sub.Pamine and .sup.fC.sub.Tamine are, respectively, the
concentrations of primary and tertiary amino groups per gram of
PAMAM respectively. .sup.gC.sub.Amide and .sup.hC.sub.Ligand are
the concentration of amide and ligand functionalities per gram of
PAMAM respectively. .sup.iD.sub.H: theoretical hydrodynamic
diameter of dendrimer molecule.
Example 2
Membrane Preparation
[0316] The membrane preparation procedures were adapted from Kotte
et al [34]. The membranes were prepared using a combined
thermally-induced phase separation (TIPS) and non-solvent induced
phase separation (NIPS) process. Table 7 lists the compositions of
the membrane casting solutions. A control PVDF membrane and two
mixed matrix PVDF membranes with in situ synthesized PAMAM
particles (MDP-G0 and MDP-G1) were prepared using the three-step
process given below. The recipe used to prepare the mixed matrix
membranes (MMMs) was selected to achieve a high particle loading
(.about.50 wt %) based on the results of our previous work on mixed
matrix PVDF membranes with in situ synthesized PEI particles [34].
The MDP-G0 and MDP-G1 membranes were prepared using G0-NH.sub.2 and
G1-NH.sub.2 PAMAM dendrimers as particle precursors,
respectively.
TABLE-US-00007 TABLE 7 Compositions of the casting solutions, neat
PVDF membrane and mixed matrix PVDF membranes with in situ
synthesized crosslinked PAMAM particles that were prepared in this
study. MDP-G0 MDP-G1 PVDF (Neat) Membrane M (g) wt (%) M (g) wt (%)
M (g) wt (%) A. Compositions of Membrane Casting Solutions
.sup.a)PVDF 18.0 11.00 18.0 10.99 18.0 15.0 .sup.b)PAMAM + 19.46
11.90 19.46 11.88 -- -- .sup.c)ECH .sup.d)TEP 120.1 73.46 120.1
73.31 102.0 85.0 .sup.e)PAMAM 5.95 3.64 6.27 3.83 -- -- Solution
(Methanol) B. Estimated Membrane Compositions (Dry mass wt %) PVDF
18.0 52.29 18.0 52.29 18.0 100 .sup.1Crosslinked 16.43 47.71 16.43
47.71 -- -- PAMAM particles C. Estimated degree of crosslinking of
PAMAM particles based on ECH concentration (Dry mass wt %)
.sup.2ECH 7.71 39.62 7.71 39.62 -- -- PAMAM 11.75 60.38 11.75 60.38
-- -- .sup.a)PVDF: Polyvinylidene fluoride; .sup.b)PAMAM:
Polyamidoamine; .sup.c)ECH: Epichlorohydrin; .sup.d)TEP: Triethyl
phosphate; .sup.e)Methanol solutions of G0-NH.sub.2 PAMAM (33.6 wt
%) and G1-PAMAM (34.79 wt %). .sup.1The mass fraction of
crosslinked PAMAM particles in each membrane was estimated based on
the following assumptions: i) All ECH crosslinker molecules were
reacted with the segregated PAMAM molecules by the reaction between
epoxy & chloro groups of ECH and primary/secondary amino groups
of PAMAM molecules in the dope solutions (FIG. 19B). ii) Each ECH
molecule produces one molecule of hydrogen chloride (HCl) following
the crosslinking reaction (FIG. 19B). iii) All unreacted PAMAM
molecules were washed away in the coagulation bath and subsequent
membrane washes with methanol and DIW. .sup.2The weight fraction
(dry mass wt %) of ECH was taken as a surrogate for the degree of
crosslinking of the PEI based on our previous work on the synthesis
of perchlorate-selective resin beads [35].
[0317] 1) Preparation of Membrane Casting Solutions.
[0318] A typical membrane casting solution was prepared by mixing
the required amounts of PVDF and TEP in a three neck round-bottom
flask equipped with a condenser and an overhead stirrer. A
homogeneous PVDF dope solution was obtained after mixing for 24
hours at 80.degree. C. Following this, the prepared PVDF dope
solution was transferred into a glass container and covered with
aluminum foil.
[0319] 2) In Situ Synthesis of Crosslinked PAMAM Dendrimer
Particles.
[0320] Prior to membrane casting, the PVDF dope solution was
homogenized at 4000 rpm for 7 minutes using a Silverson L5M high
shear mixer (HSM). During the homogenization, the temperature of
the dope solution was raised to 80.degree. C. and kept constant. A
solution of PAMAM in TEP was then added drop wise to the PVDF dope
solution for 5 minutes followed by high shear mixing for 15 minutes
to obtain a homogeneous PVD+PAMAM dispersion in TEP. A solution of
ECH in TEP was then added drop wise to the dispersion and
homogenized for 5 minutes under similar HSM conditions to obtain a
stable dispersion of PAMAM particles in the PVDF+TEP dope. Finally,
the curing reaction was continued in a round bottom flask equipped
with an overhead stirrer at 80.degree. C. for 3 hours.
[0321] 3) Membrane Casting.
[0322] Following the completion of the curing reactions, the
dispersion of PVDF+TEP+ECH crosslinked PAMAM particles dope was
allowed to cool to ambient temperature to initiate the TIPS step of
the membrane casting process. The membranes were prepared with and
without a polyethylene terephthalate (PET) microporous support. To
prepare a membrane without support, the cooled dispersion of
PVDF+PAMAM particle in TEP was poured onto a clean glass plate. A
casting knife (BYK Chemie) [with 300 m air gap] was used to
uniformly coat the casting solution onto the glass plate. The
nascent membrane was kept for 30 seconds at ambient temperature
(25.+-.1.degree. C., RH: 55%) followed by immersion into a DIW bath
with a temperature of 23.+-.1.degree. C. After 1 hr. the nascent
membrane was transferred to a fresh DIW bath and immersed for 24 h.
Following this, the membrane was soaked in ethanol for 10 h.
Finally, the membranes were air dried and stored in a desiccator. A
similar procedure was used to prepare a membrane with microporous
support by pouring the casting solution on a PET non-woven fabric.
The supported membranes were stored in DIW with the water
periodically replaced with fresh DIW until the metal binding
experiments were initiated.
Example 3
Membrane Characterization
[0323] 1) Membrane Morphology.
[0324] The cross-sectional and top surface of each membrane was
imaged with a field emission scanning electron microscope (FESEM,
Magellan Series 400, FEI Corporation) at an acceleration voltage of
2.0 kV. Before imaging, all samples were first coated with platinum
for 30 seconds followed by osmium for 30 seconds to minimize the
charging effect. To obtain the membrane cross section morphology,
the membranes were frozen and fractured following immersion in
liquid nitrogen. The SEM images were subsequently analyzed to
estimate membrane thickness and PAMAM particle size using the Image
J Version 1.45 m image processing/analysis software [36].
[0325] 2) N.sub.2 Adsorption Permporometry.
[0326] The average pore diameter of each membrane top/skin layer
was determined by N.sub.2 adsorption permporometry [12] at 77 K
using a Micromeritics ASAP 2020 accelerated surface area and
porosimetry analyzer. The Barrett-Joyner-Halenda (BJH) methodology
was utilized to extract membrane pore diameters from the N.sub.2
adsorption/desorption data [37].
[0327] 3) Membrane Surface Composition.
[0328] The surface chemical composition was characterized by
Fourier transform infrared (FT-IR) spectroscopy. The mid IR spectra
(500 cm.sup.-1 to 4000 cm.sup.-1) of the membranes were scanned in
attenuated total reflectance (ATR) mode. The spectra were acquired
by averaging 32 scans at a resolution of 2 cm.sup.-1 using a JASCO
4100 FT-IR spectrometer (Japan) and a zinc selenide ATR crystal
plate with an aperture angle of 45.degree.. In contrast, the near
IR (NIR) spectrum of each membrane (4000 cm.sup.-1 to 10000
cm.sup.-1) was recorded by reflection using a Bruker MPA FT-NIR
spectrometer equipped with a quartz beam splitter and an external
RT-PbS detector. The NIR spectra were acquired by averaging 32
scans at a resolution of 8 cm.sup.-1. The elemental composition of
each membrane surface was analyzed by X-ray photoelectron
spectroscopy (XPS) using an SSX-100 UHV spectrometer from Surface
Science Instruments. The sample was irradiated with a beam of
monochromatic Al K.alpha. X-rays with energy of 1.486 keV.
[0329] 4) Contact Angle Measurements.
[0330] The hydrophobicity of each membrane was determined from
contact angle measurements using a Phoenix 300 contact angle
analyzer. A micro syringe was utilized to place a water droplet on
the surface of each membrane. After 30 and 120 seconds, the image
was captured and analyzed using the instrument's image processing
software. Each reported contact angle is the average of five
different measurements.
[0331] 5) Particle Size Measurements by DLS.
[0332] A 0.2 g of dry membrane was added to 20 g of TEP solvent in
sample vial. It was allowed for dissolution for 15 hours at ambient
temperature as a result fine dispersion was obtained. Then the
dispersion was sonicated for 15 minutes. A 1.0 mL aliquot was
sampled from the dispersion and diluted with 10 mL of TEP solution
for the DLS measurements. These were conducted in duplicate at
25.degree. C. using TEP solvent.
[0333] 6) Zeta Potential Measurements.
[0334] The zeta potentials of the membranes were determined using
the electrophoresis method [38]. An ELSZ-2 electrophoretic light
scattering spectrophotometer from Otsuka Electronics. Japan [with a
plate quartz cell as membrane holder] was employed to measure the
electrophoretic mobility of the monitoring particles. The
monitoring particles consisted of polystyrene (PS) latex particles
(Otsuka Electronics, Japan) with an amide surface coating and
diameter of 520 nm. The PS particles were dispersed in 0.01 M NaCl
solutions at pH 7.0. The measured electrophoretic mobilities (U) of
the monitoring PS particles [cm.sup.2/(Vs)] were utilized to
calculate membrane zeta potentials () [mV] using the Smoluchowski
equation as given below [38]:
.zeta. = 4 .pi..eta. U r 0 Eq 1 ##EQU00002##
where .eta. is the liquid viscosity (0.89.times.10 Pa.sup.-3 Pas),
e.sub.f is the relative permittivity of liquid (78.38) and e.sub.0
is the vacuum permittivity (8.854.times.10.sup.-12 sm.sup.-1).
Example 4
Copper Filtration and Binding Studies
[0335] The Cu(II) filtration and binding experiments were conducted
on a custom-made cross-flow UF system with an active filtration
area of 24 cm.sup.2. The filtration cell (17.62 cm in length; 2.54
cm in width and 0.3 cm in depth), pump head, reservoir and tubing
were built using Teflon and polyvinyl chloride (FIG. 20) to
eliminate metal ion sorption onto the system components. The flow
rate was maintained at .about.1.7 L/min with a crossflow velocity
of .about.37.2 cm/s.
[0336] Each filtration experiment consisted of four steps. The pH
of the feed water was adjusted with a solution of 0.1 N HCl or 0.1
N NaOH as needed. Each membrane was first compacted by running DIW
for 1 hour at a pressure of 3 bar. The pressure was then reduced to
2 bar and aliquots of permeate were collected every 5 minutes for 1
hour to estimate membrane water flux. Following this, a constant-pH
solution was pumped through each membrane and aliquots of permeate
were collected every 5 minutes for 30 minutes. After the completion
of the constant-pH water flux measurements, a 2 L of a solution of
Cu(II) [10 mg/L] at constant pH (3, 7 and 9) was pumped through
each membrane at 2 bar. In this case, permeate samples were
collected every 5 minutes for 3 hours. Following the flux
measurements, the permeate samples were poured back into the UF
system feed tank (FIG. 20) to keep the volume of the feed (2 L)
constant; i.e. within 2%.
[0337] The permeate flux (J.sub.n) [L m.sup.-2 hr.sup.-1] at time
t.sub.n through each membrane was expressed as:
J n = V p At o Eq . 2 ##EQU00003##
where V.sub.p is the volume of permeate (L) collected at time
t.sub.n (hr) and A is the effective membrane area (m.sup.2). For
the Cu(II) binding assays, aliquots (1 mL) of feed and permeate
solutions were sampled every 5 minutes for a period of 1 hour and
then every 30 minutes for the remainder of the run time. The
collected samples were diluted with a 3 wt % HNO.sub.3 solution and
analyzed by inductively coupled plasma mass spectrometry (ICP-MS)
using an Agilent ICP-MS 7700x instrument.
[0338] The mass of Cu(II) bound M.sub.t.sub.n.sup.m (mg per mL of
dry membrane) at time t.sub.n was expressed as:
M tn m = ( V t n F C t n F - V t n P C t n P ) A m d m Eq . 3
##EQU00004##
where V.sub.tm.sup.F and V.sub.tm.sup.P are, respectively, the
volumes of feed and permeate at time t.sub.n; C.sub.tm.sup.F and
C.sub.tm.sup.P are, respectively, the copper concentrations in the
feed and permeate at time t.sub.n, and A.sub.m and d.sub.m are,
respectively, the membrane area and thickness. To account for the
addition of a permeate sample in the feed following the completion
of a flux measurement, a corrected copper correction in the feed at
time t.sub.n (n>0) was estimated by mass balance using the
equation given below:
C t n F = C t n - 1 F V t n - 1 F + C n t - 1 P V t n - 1 PSF V t n
- 1 F + V t n - 1 PSF Eq . 4 ##EQU00005##
where C.sub.t.sub.n.sup.F and C.sub.t.sub.n-1.sup.F are,
respectively, the copper concentration in the feed at times t.sub.n
and t.sub.n-1: C.sub.t.sub.n-1.sup.F is copper concentration in the
permeate at time t.sub.n-1; V.sub.t.sub.n-1.sup.F is the volume of
feed at time t.sub.n-1 and V.sub.t.sub.n-1.sup.PSF is the volume of
permeate sample that was poured back to the feed at time
t.sub.n-.
Example 5
Membrane Preparation, Morphology and Bulk Properties
[0339] PAMAM dendrimers were the first class of dendrimers to be
commercialized[17]. They possess functional nitrogen and amide
groups arranged in regular "branched upon branched" patterns, which
are displayed in geometrically progressive numbers as a function of
generation level. This high density of N and O donors make PAMAM
dendrimers particularly attractive as high capacity and selective
chelating agents for transition metal ions such as Cu(II) [39],
[40], [41], [24]. Diallo et al. [23] have developed a dendrimer
enhanced filtration (DEF) process that can recover Cu(II) from
aqueous solutions using UF. Although higher generation PAMAM
dendrimers (e.g. G3-G5 NH.sub.2) have shown excellent potential as
high capacity, selective and recyclable macroligands for Cu(II)
recovery from aqueous solutions using DEF.sup.[23] and dendronized
PAMAM hollow fiber membranes [39], they are expensive to produce
due to the large number of synthetic and purification steps
required to prepare such macromolecules. To further exploit the
high metal ion chelating capability of PAMAM dendrimers for Cu(II)
recovery from aqueous solutions, it is described herein the
preparation of a new family of mixed matrix PVDF membrane absorbers
with in situ synthesized particles using low-generation PAMAM
dendrimers (G0-NH.sub.2 and G1-NH.sub.2) as precursors.
[0340] A standard procedure for the preparation of mixed matrix
membranes involves the dispersion of preformed micro/nanoparticles
in a suitable polymer solution followed by membrane casting.
However, the synthesis of preformed PAMAM micro/nanoparticles will
require the use of surfactant-stabilized inverse suspensions
systems [35]-[42] followed by tedious and lengthy purifications to
produce the clean particles required for the preparation of high
quality dope solutions for the synthesis of PVDF-PAMAM membrane
absorbers.
[0341] FIG. 19A illustrates the one-pot method that was employed to
prepare our new mixed matrix PVDF membranes including (i) dope
preparation, (ii) in situ PAMAM particle synthesis and (iii) phase
inversion casting. It is worth mentioning that this membrane
preparation is simple, versatile and potentially scalable. All the
components of the mixed matrix PVDF membranes with in situ
synthesized are prepared in a one-pot dispersion (FIG. 19A) prior
to membrane casting. FIG. 19B depicts the crosslinking reaction
between a G1-NH.sub.2, PAMAM macromolecule and an ECH molecule in
the membrane casting solution. Kotte et al. [43] provide a detailed
discussion of the reactions of ECH with the primary/amino groups of
functional polymers with amine groups such branched
polyethyleneimine (PEI).
[0342] The selection of PVDF, ECH and G0/G1-NH.sub.2 PAMAM
dendrimers as building blocks for the generated mixed matrix PVDF
membrane absorbers was motivated by several considerations.
Firstly, PVDF is widely used as base polymer in the fabrication of
commercial UF/MF membrane due to its high tensile strength, and
thermal and chemical resistance [42]. PVDF membranes can be
prepared by phase inversion casting using TIPS and/or NIPS [35].
This provides many degrees of freedom for optimizing the
microstructures of the mixed matrix PVDF membrane absorbers by
selecting the appropriate synthesis conditions. Secondly, the high
reactivity of ECH toward functional macromolecules and oligomers
containing primary and secondary amino groups was exploited to
prepare a broad range of separation membranes and media [34], [43],
[44], [23], [35]. Thirdly, the low-generation PAMAM dendrimers (G0
and G1-NH.sub.2) have (i) well defined compositions, (ii) low
molecular weights (M.sub.n of 517 and 1430 Da) and (iii) high
density of functional N and O donors (.about.19 meq/g) for metal
ion complexation (Table 1). Moreover, the G0 and G1-NH.sub.2 PAMAM
are much less expensive to produce and have the required primary
amine groups (NH.sub.2) for in situ crosslinking with ECH [34],
[43], [44] in the dope solutions prior to membrane casting (FIG.
19B).
[0343] Two mixed matrix PVDF membranes with in situ synthesized
PAMAM particles (MDP-G0 and MDP-G1) and a control (neat) PVDF
membrane were prepared in this study. Table 7 lists the composition
of the casting solution for each membrane. Table 8 lists the
estimated compositions (on a dry basis) of the neat PVDF membrane
and mixed matrix PVDF membranes that were prepared in this study.
The recipes used to prepare the currently disclosed mixed matrix
membranes (MMMs) were adapted from the previous studies [34], [43],
[44] to achieve a high loading (.about.48 wt %) of in situ
synthesized PAMAM particles with a degree of crosslinking (i.e.
particle ECH wt %) of 40%.
TABLE-US-00008 TABLE 8 Estimated compositions of the mixed matrix
PVDF membranes with in situ synthesized PAMAM particles and neat
PVDF membranes that were prepared in this study. Mixed-Matrix
.sup.aW.sub.PVDF .sup.bW.sub.XLP .sup.cW.sub.ECH .sup.dC.sub.Pamine
.sup.eC.sub.Samine .sup.fC.sub.Tamine .sup.gC.sub.Amide
.sup.hC.sub.Ligand Membrane (Wt %) (Wt %) (Wt %) (meq/g) (meq/g)
(meq/g) (meq/g) (meq/g) MDP-G0 52.29 47.71 39.62 0 2.65 1.33 2.65
9.29 MDP-G1 52.29 47.71 39.62 0 1.91 1.43 2.86 9.06 PVDF (Neat) 100
0 0 0 0 0 0 0 .sup.aW.sub.PVDF: estimated mass fraction of PVDF in
the dry membrane .sup.bW.sub.XLP: the mass fraction of crosslinked
PAMAM particles in the dry membrane was estimated based on the
following assumptions: i) All ECH crosslinker molecules were
reacted with the segregated PAMAM molecules by the reaction between
the epoxy & chloro groups of ECH and the primary amino groups
of PAMAM molecules in the dope solution (FIG. 19B). ii) Each ECH
molecule produces one molecule of hydrogen chloride (HCl) following
the crosslinking reaction (FIG. 19B). iii) All unreacted PAMAM
molecules were washed away in the coagulation bath and subsequent
membrane washes with methanol and DIW. .sup.cW.sub.ECH: the mass
fraction of ECH was taken as a surrogate for the degree of
crosslinking of the in situ synthesized PAMAM particles based on
our previous work on the synthesis of perchlorate-selective PEI
resin beads.sup.[42]. .sup.dC.sub.Pamine, .sup.eC.sub.Samine and
.sup.fC.sub.Tamine are the estimated concentrations of primary,
secondary and tertiary amine groups in milli equivalents (meq) per
gram of dry membrane respectively. .sup.gC.sub.Amide and
.sup.hC.sub.Ligand are the estimated concentration of amide and
ligands (i.e. N and O donors) meq per gram of dry membrane,
respectively.
[0344] A combined TIPS and NIPS casting process was employed to
prepare the disclosed MMMs. For the characterization experiments,
the membranes were prepared without a polyethylene terephthalate
(PET) microporous support.
[0345] FIG. 21 shows FESEM cross-section micrographs of the neat
PVDF membrane (Panels A and B). MDP-G0 membrane (Panels C and D)
and MDP-G1 membrane (Panels E and F). Table 9 lists selected
physicochemical properties of these membranes. FIG. 21 and Table 9
indicate that the neat PVDF membrane exhibits an asymmetric
structure with a dense skin (.about.15.0 .mu.m) and a matrix with a
sponge like microstructure consisting of PVDF spherulites.
Similarly, the MDP-G0 and MDP-G1 membranes are asymmetric with
dense skins (.about.8-12 .mu.m) and matrices with sponge-like
microstructures containing mixtures of PAMAM particles and PVDF
spherulites (FIG. 21). The sponge-like microstructures of the MMMs
is primarily attributed to the crystallization-induced gelation
process that occurred during the TIPS process.sup.32 when the hot
membrane casting solutions (80.degree. C.) were cooled down to
ambient temperature prior to immersion into the DIW bath.
TABLE-US-00009 TABLE 9 Selected physicochemical properties of the
mixed matrix PVDF membranes with in situ synthesized PAMAM
particles and neat PVDF membrane that were prepared in this study.
Property MDP-G0 MDP-G1 PVDF (Neat) .sup.aThickness of membrane
surface 11.78 7.58 15.0 layers ( m) Thickness of dry membrane ( m)
150.0 151.5 103.5 .sup.bContact angle (Degree) 56.0 59.0 87.0
.sup.cZeta potential at pH 7.0 (mV) 0.93 0.46 -5.9 .sup.dAverage
pore diameter (nm) Adsorption 44.6 28.03 16.87 Desorption 26.7
22.48 12.79 .sup.eCrosslinked PAMAM particle diameter by FESEM (nm)
Minimum 335 816 .sup.gNA Maximum 2890 3341 .sup.gNA Average 1501
2284 .sup.gNA .sup.fCrosslinked PAMAM particle diameter by DLS (nm)
Minimum 816 1801 .sup.gNA Maximum 1309 3179 .sup.gNA Average 1373
2442 .sup.gNA .sup.aEstimated average thickness of each membrane
surface layer from the FESEM micrographs using the Image J software
(35). bMeasured contact angle after 120 seconds. .sup.cMeasured
zeta potential at pH 7.0. .sup.dAverage pore diameter of the top
layer (i.e. skin) of each membrane. The pore diameters were
estimated from the N.sub.2 adsorption permporometry experiments
using the Barrett-Joyner-Halenda (BJH). methodology (FIG. 24-26).
.sup.eEstimated size range crosslinked PAMAM embedded particles
using FESEM micrographs analyzed by Image J software (Table 8).
.sup.fEstimated size range of crosslinked PAMAM embedded particles
from DES particle size analysis. .sup.gNA: Not Applicable
[0346] FIG. 22 shows magnified FESEM micrographs (1000.times.) of
the top cross-sections of the MDP-G0 and MDP-G1 membranes. These
micrographs confirm that the PAMAM particles are present in both
the matrices and top surfaces of the MMMs.
[0347] FIG. 23 indicates that the top surfaces of the mixed matrix
PVDF membranes appear to be more porous than that of the neat PVDF
membrane as illustrated by the corresponding SEM micrographs. The
N.sub.2 permporometry measurements (see FIGS. 24-26 and Table 9)
indicate that the skin layer of the MDP-G0 membrane has larger pore
diameters (.about.27-45 nm) than those of the MDP-G1 membrane
(.about.23-28 nm) and neat PVDF membrane (.about.13-17 nm). FIG. 21
and FIG. 22 also show that the PAMAM particles are uniformly
distributed throughout the cross-section of MMMs.
[0348] The SEM analysis Image J software [36] is subsequently
utilized to extract estimates of the size ranges of the embedded
PAMAM particles for each mixed matrix PVDF membrane (see Table 5).
Table 10 indicates that the average diameters of PAMAM particles of
the MDP-G0 and MDP-G1 membranes are, respectively, equal to
.about.1.5 and 2.3 .mu.min. To validate the FESEM particle size
estimates, DLS measurements of dispersions of PAMAM particles
obtained by dissolving the MMMs in TEP were carried out. These
measurements confirm that the sizes of the PAMAM particles in the
TEP dispersions (.about.1.4 to 2.3 .mu.m) are comparable to the
FESM particle size estimates (Table 10 and FIGS. 27 and 28).
TABLE-US-00010 TABLE 10 Estimated diameters of the embedded PAMAM
particle of the mixed matrix MDP-G0 and MDP-G1 membranes using
FESEM with the image processing/analysis software ImageJ.[45]
Particle Diameter (nm) Image No MDP-G0 MDP-G1 1 1867 2572 2 2370
3127 3 383 2459 4 1293 3342 5 1029 2411 6 814 3055 7 335 1361 8 359
740 9 2968 2817 10 1269 2530 Average Diameter (nm) 1269 2441
Minimum (nm) 335 740 Maximum (nm) 2968 3342
Example 6
Membrane Surface Composition and Physicochemical Properties
[0349] Zhang et al.[46] have shown that dendronized PAMAM HFMs can
act as nucleation sites and supports for the formation and
precipitation of copper hydroxide mineral scales as they become
saturated with Cu(II) ions. Therefore, the knowledge gained during
the previous investigations of mixed matrix membranes with in situ
synthesized and PEGYlated PEI particles.sup.[43, 44] was utilized
to prepare new PVDF-PAMAM membrane absorbers with hydrophilic and
neutral surface layers. Based on the results of these previous
studies.sup.[43, 44], it is expected that the surface layers of
such membranes to exhibit good fouling resistance and lower scaling
tendency. The FT-IR spectra corroborate the presence of PAMAM
particles at the surfaces of the MDP-G0 and MDP-G1 membranes.
[0350] FIG. 29A shows that the mid IR spectra of both membranes
exhibit four new peaks including (i) --OH and --NH stretching (3313
cm.sup.-1) from the amide, secondary amino or hydroxyl groups of
the ECH crosslinked PAMAM particles, (ii) --C.dbd.O stretching
(1640 cm.sup.-1) from the amide groups of the PAMAM particles;
(iii) --NH bending (1540 cm.sup.-1) from the amide/amine groups of
PAMAM particles and (iv) --C--N stretching (1270 cm.sup.-1) from
the amine groups of PAMAM particles [43], [34], [44], [47]. The
near IR spectra (FIG. 29B) provide additional supporting evidence
for the presence of PAMAM particles with --OH groups at the
surfaces of these membranes including: (i) first overtone of --OH
stretching vibrations (6914 cm.sup.-1), (ii) first overtones of
--CH and --CH.sub.2 stretching vibrations (5783 cm.sup.-1) and
(iii) combination of --NH.sub.2 stretching and bending vibrations
(5115 cm.sup.-1) [43], [34], [44]. The XPS experiments also
corroborate the presence of PAMAM particles with high density of OH
groups at the surfaces of the mixed matrix PVDF membranes.
[0351] FIG. 30 shows that the atomic concentrations of oxygen (O1s)
of the MDP-G0 and MDP-G1 membranes are, respectively, equal to 2.71
and 3.81 wt %. It is worth mentioning that the concentrations of
nitrogen (N1s) are significantly lower for both MMMs; i.e. 0.22 wt
% for MDP-G0 and 0.47 wt % for MDP-G1. The zeta potential (ZP)
measurements (Table 4) indicate that the PVDF-PAMAM membrane
absorbers have neutral surface charges with ZP values respectively
equal to 0.93 mV and 0.46 mV for the MDP-G0 and MDP-G1 membranes
compared to -5.9 mV for the neat PVDF. These results suggest that
the ECH crosslinked PAMAM particles expose their OH groups at the
surface of the mixed matrix PVDF membranes. This observation is
primarily attributed to more favorable interactions between the
PAMAM particles and the non-solvent (DIW) during the coagulation
phase of the membrane casting process (FIG. 19A). This causes the
ECH crosslinked PAMAM particles to migrate at the surface of the
MMMs and expose their OH groups as they become incorporated in the
membrane surface layers (FIG. 22).
Example 7
Copper Filtration and Binding Studies
[0352] The overall results of the characterization experiments
indicate that the MDP-G0 and MDP-G1 membranes are asymmetric with
(i) neutral and hydrophilic surface layers of average pore
diameters of 23-45 nm and (ii) high loadings of in situ synthesized
PAMAM particles (.about.48 wt %) containing .about.9.0 meq of N and
O donors per g of dry membrane (Table 3). These membranes also
exhibit the sponge-like microstructures (FIG. 21) that are
typically found in UF membranes with strong mechanical
integrity..sup.37
[0353] Filtration experiments were carried out to evaluate the
utilization of MDP-G0 and MDP-G1 as membrane absorbers for Cu(II)
recovery from aqueous solutions by low-pressure UF at 2 bar. Three
objectives of these experiments were to: 1) assess the effects of
solution pH on Cu(II) uptake by the PVDF-PAMAM membrane absorbers,
2) evaluate the scaling potential of these membranes and 3) gain
insight into the mechanisms of Cu(II) coordination with the N and O
donors of their embedded PAMAM particles.
[0354] FIG. 31 shows the flux of DIW through the MMMs as a function
of time at 2 bar. The average water flux of the MDP-G0 and MDP-G1
membranes are, respectively, equal to .about.427.+-.13 and 107.+-.4
LMH (FIG. S10). In contrast, the neat PVDF membrane has a very low
water flux: i.e. less than 3.0 LMH (data not shown). The higher
flux of the MDP-G0 membrane is attributed to its lower contact
angle (i.e. higher hydrophilicity) and the larger pore diameters of
its surface layer; i.e. .about.27-45 nm compared to .about.22-28 nm
for those of the MDP-G1 membrane.
[0355] FIGS. 31-33 and Tables 11-12 summarize the results of the
Cu(II) filtration and binding experiments at 2 bar and pH 3.0, 7.0
and 9.0. It is worth mentioning that the absence of Cu(OH).sub.2
precipitates in the feed solution is consistent with the
differences between the measured fluxes of the Cu(II) solutions for
the MDP-G0 and MDD-G1 membranes. If there were Cu(II) precipitation
in the feed solutions, the measured permeate fluxes at 2 bar would
drop significantly (close to zero) due to the formation and buildup
of micron-size Cu(OH).sub.2 scales at the surface of the membranes.
However, FIG. 32 indicates that the permeate flux of aqueous
solutions of Cu(II) through the MDP-G1 membrane initially decreases
and then stabilize around a value of 60, 60 and 42 LMH at pH 3.0,
7.0 and 9.0 respectively. A similar trend (with a less pronounced
initial flux decline at pH 9) is also observed for the MDP-G0
membrane. In this case, the steady state permeate fluxes of the
Cu(II) solutions are, respectively, equal to 395, 275 and 213 LMH
at pH 9.0, 7.0 and 3.0 (FIG. 32 and Table 11). These results are
consistent with a flux decline mechanism caused by pore blockage
due to Cu(II) binding to the embedded PAMAM particles of the MDP-G0
and MDP-G1 membranes.
[0356] FIG. 33 and Table 12 show that Cu(II) sorption onto the
MDP-G0 membrane reaches saturation during the course of the
filtration run (3 hours) at pH 3.0, 7.0 and 9.0. In all cases, the
MDP-G0 membrane binds less than 25% of the amount of Cu(II) in the
feed solution with a binding capacity of .about.46-52 mg of Cu(II)
per mL of dry membrane (Table S5). In contrast, the MDP-G1 membrane
can bind .about.51.+-.3.6 mg of Cu(II) per mL of dry membrane at pH
9 without reaching saturation (i.e. with a mean percentage of bound
copper of .about.99%) (Table S5). At pH 3.0 and 7.0, the MDP-G1
membrane can bind 54-57 mg of Cu(II) per mL of dry membrane with
mean percentages of bound copper of 75 and 82%, respectively.
[0357] FIG. 33 and Table 12 indicate that the mean percentage of
bound copper for the MDP-G1 membrane (.about.99%) at pH 9.0 is
larger than that of the MDP-G0 membrane (.about.20%) even though
both sorbents have equal concentrations of N and O donors
(.about.9.0 meq/g) (Table 8). It is speculated that the in situ
synthesized PAMAM particles of the MDP-G1 membrane behave as high
generation dendrimer-like particles (DLPs) that can bind Cu(II)
through several mechanisms including (i) coordination with their N
and O donors and (ii) non specific binding to water molecules
and/or counterions trapped inside the DPLs [39], [40], [41], [24],
[48-50].
TABLE-US-00011 TABLE 11 Permeate fluxes of aqueous solutions Cu(II)
[10 mg/L] trough the mixed matrix MDP-G0 and MDP-G1 membranes as a
function of filtration time at 2 bar pressure Flux (LMH) MDP-G0
MDP-G1 Time (Minutes) pH 3.0 pH 7.0 pH 9.0 pH 3.0 pH 7.0 pH 9.0 0
-- -- -- -- -- -- 5 342.31 345.6 529.12 96.15 78.57 36.81 10 336.81
348.35 499.45 90.11 70.33 36.81 15 329.57 324.18 485.16 86.26 67.58
37.91 20 321.43 324.73 471.43 84.62 64.84 38.46 25 312.64 307.69
466.48 82.42 65.38 37.36 30 304.95 319.23 445.6 80.77 63.19 40.66
35 298.9 336.26 440.66 79.12 61.54 36.26 40 295.05 320.88 428.57
76.92 59.89 36.26 45 287.91 339.01 425.82 76.92 61.54 35.16 50
281.32 327.47 418.13 77.47 61.54 38.46 55 278.57 307.69 415.38
76.37 59.89 35.71 60 274.73 293.41 415.38 75.27 59.34 36.26 90
250.55 258.24 386.26 72.25 58.97 38.55 120 233.52 270.88 392.86
68.13 57.42 41.48 150 221.98 278.02 373.63 63.19 58.15 42.95 180
213.19 275.82 395.05 58.97 58.42 42.58 Average 286.47 311.09 436.81
77.81 62.91 38.23 SD 39.87 28.12 43.69 9.45 5.52 2.45
TABLE-US-00012 TABLE 12 Extent of binding [mg of Cu(II) per mL of
membrane] and mean % Cu bound in aqueous solutions by the mixed
matrix MDP-G0 and MDP-G1 membranes as a function of filtration time
and solution pH pH 3.0 pH 7.0 pH 9.0 MDP-G0 MDP-G1 MDP-G0 MDP-G1
MDP-G0 MDP-G1 Cu(II) Cu Cu(II) Cu Cu(II) Cu Cu(II) Cu Cu(II) Cu
Cu(II) Cu Time binding bound binding bound binding bound binding
bound binding bound binding bound (Mins) (mg/mL) (%) (mg/mL) (%)
(mg/mL) (%) (mg/mL) (%) (mg/mL) (%) (mg/mL) (%) 0 0 0 0 0 0 0 0 0 0
0 0 0 5 56.19 24.4 62.41 69.77 55.44 52.86 59.51 95.18 52.81 58.31
55.03 99 10 55.53 15.27 61.89 64.38 54.05 31.17 58.98 91.09 50.71
31.44 54.74 98.87 15 55.13 14.53 61.41 68.81 53.41 28.24 58.46
88.61 49.81 26.93 54.39 98.91 20 54.76 16.98 60.85 71.22 52.7 24.36
57.9 86.88 49.03 23.71 53.99 98.92 25 54.21 13.45 60.23 72.78 52.11
22.39 57.31 85.05 48.3 22.44 53.54 98.96 30 53.77 17.07 59.55 74.32
51.45 22.89 56.68 84.86 47.62 20.89 53.04 99.01 35 53.16 15.49
58.82 75.39 50.67 20.66 56.01 83.93 46.9 19.56 52.47 99.07 40 52.56
16.92 58.05 76.76 49.99 18.43 55.3 82.72 46.2 18.11 51.88 99.04 45
51.91 18.36 57.22 77.06 49.21 18.01 54.56 82.06 45.45 16.6 51.25
99.01 50 51.13 14.38 56.35 77.71 48.5 17.61 53.76 80.84 44.73 16.17
50.58 98.97 55 50.5 21.14 55.43 77.95 47.78 15.81 52.93 79.67 43.98
14.16 49.85 98.95 60 49.59 15.45 54.47 78.27 47.05 14.3 52.07 79.72
43.23 13.35 49.09 98.94 90 48.94 22.24 53.1 78.46 46.46 18.4 50.84
76.8 42.57 12.7 48.29 98.94 120 48.14 27.34 50.84 79.47 45.59 19.59
48.92 75.4 41.74 9.58 46.64 98.91 150 47.21 29.38 48.69 79.46 44.65
17 47.05 73.52 40.93 0.72 44.93 98.89 180 46.25 31.88 46.67 79.63
43.77 16.75 45.24 72.32 40.27 5.12 43.21 98.68 Average 51.81 19.64
56.62 75.09 49.55 22.40 54.10 82.42 45.89 19.36 50.81 98.94 SD 3.12
5.80 4.79 4.51 3.51 9.30 4.32 6.28 3.68 12.97 3.58 0.09
[0358] To gain insight into the mechanisms of Cu(II) binding to the
mixed matrix membrane absorbers, a sample of Cu(II) loaded MDP-G0
membrane was characterized by FESEM, FT Raman spectroscopy and XPS.
The FESEM micrographs (FIG. 34) show that no solid copper
precipitates were formed at the surface and inside the matrix of
the Cu(II) laden MDP-G0 membrane. In contrast, Zhang et al. [46]
reported the formation of Cu.sub.2(OH).sub.3C1 crystals (FIGS.
37A-B) following the incubation of a G3-NH.sub.2 dendronized PAMAM
HFM with an aqueous solution of Cu(II) [.about.12 mg/L] at room
temperature for 72 h.
[0359] The FT Raman spectra (FIG. 35A) exhibit the typical PVDF
bands including (i) CH.sub.2 bending (1421 cm.sup.-1) and (ii) CF
stretching (796 cm.sup.-1) [51]. The intense Raman peak (1050
cm.sup.-1) of FIG. 35A is attributed to C--N stretching resulting
from the coordination of Cu(II) with the amino groups of the
embedded PAMAM particles of the MDP-G0 membrane. The XPS spectra
(FIGS. 35B-D) provide further supporting evidence for the
coordination of Cu(II) with the N and O donors of the membrane
embedded PAMAM particles. The shift of the C1s peak toward higher
binding energy (283.8 eV) (FIG. 35C) [51], the splitting and
increase in the intensity of the O1s.sub.1/2 peak [51] (FIG. 35D)
and the appearance of a N1s peak around 400 eV (FIG. 36) are all
consistent with Cu(II) coordination with the membrane N and O
donors.
[0360] FIG. 38 provides a schematic illustration of the postulated
copper coordination sites within the embedded PAMAM particles of
our new mixed matrix PVDF membrane absorbers. Based on the results
of the previous work and published literature on the mechanisms of
Cu(II) binding to PAMAM dendrimers in aqueous solutions.sup.[24,
39-41], [48-50], it is hypothesized that three classes of complexes
(FIG. 38) could be formed depending on metal ion loading and
solution pH including (i) complexes of Cu(II) with four nitrogen
donors (Complexes A1, A2, A3 and A4), (ii) complexes of Cu(II) with
two nitrogen donors and two oxygen donors (Complexes B1 and B2) and
(iii) complex of Cu(II) with six water molecules. More in-depth
investigations will be required to validate the postulated
mechanisms of Cu(II) binding to the embedded PAMAM particles of the
mixed matrix PVDF membrane absorbers (FIG. 38).
Example 9
Mixed Matrix Membranes with In Situ Synthesized Dendrimer Particles
as Supercontainers for Pt(0)
[0361] Crooks and co-workers [2, 52] have reported the successful
use of PAMAM and poly(propyleneimine) (PPI) dendrimers to prepare a
variety of DEN (.about.3 nm in size) including Pd(0) DENs, Pt(0)
DEN and bimetallic Pd(0)/Pt(0) DEN. It was found that these DENs
can serve as homogeneous and heterogeneous catalysts for (i)
hydrogenation and Suzuki carbon-carbon coupling reactions. [2] [52]
By immobilizing DENs onto electrode surfaces, Crooks and co-workers
were able to prepare Pt(0) and Pt(0)Pd(0) electrocatalysts for
oxygen reduction reactions (ORR). Although higher generation PAMAM
dendrimers (e.g. G4-G6 NH.sub.2) are potential templates for the
preparation of redox and catalytic DENs [Cu(0), Pt(0) and Pd(0)],
they are expensive due to the multiple steps required for their
synthesis and purification.
[0362] The same methods described in Examples 1-6 were used herein
for the preparation of the mixed matrix PVDF UF membranes with in
situ synthesized PAMAM dendrimer particles as supercontainer for
Pt(0) nanoparticles.
[0363] A reactive encapsulation process (see FIG. 40) is utilized
to prepare the new families of PVDF UF membranes with in situ
synthesized PAMAM dendrimer particles for Pt(0). PVDF UF membrane
with in-situ generated PAMAM particles (MDP-G1) was synthesized
using a G1-NH.sub.2 PAMAM dendrimer as particle precursor. A cross
flow system with an active filtration area of 24 cm.sup.2 was used
to load the membranes (MDP-G1) with Pt.sup.4+ ions (FIG. 41). The
membrane was first compacted by running DI water for 1 hour at a
pressure of 3 bar followed by water flux measurement for a period
of 30 minutes. Pressure was reduced to 2 bar and the DI water flux
was measured every 5 minutes for an hour. Thereafter, the DI water
was drained and pH adjusted solution (pH 3, 7 and 9) introduced
into the feed tank. Flux measurements were made every 5 minutes for
30 minutes. After the membrane conditioning, the Pt.sup.4+ solution
(10 ppm, 2 L) was introduced into the feed tank. The Pt.sup.4+
binding experiment was performed at 2 bar, with flux measurements
every 5 minutes for a period of 1 hour and then every 30 minutes
for 2 hrs. Permeate and feed aliqouts (1 mL) were sampled every 5
minutes for a period of 1 hour and every 30 minutes thereafter for
the remainder of the run time. The initial and final volumes of the
feed and permeate solutions were recorded. The concentration of
Pt.sup.4+ in the feed and permeate solutions were measured by
inductively coupled plasma mass spectrometry (ICP-MS). FIGS. 41-42
summarize the results of the Pt.sup.4+ loading experiments.
[0364] Following completion of the metal loading experiments, a
small piece of the platinum loaded MDP-G1 membrane (pH 9) was
immersed in a centrifuge tube containing 50 mL of an aqueous
solution of NaBH.sub.4 (100 ppm) and mixed on a rotary shaker for
about an hour to allow the reduction of the PAMAM complexed
Pt.sup.4+ to Pt(0). The resulting dark colored membrane was then
washed with DI water (FIG. 40). The Pt(0) loaded MDP-G1 membrane
was characterized by scanning electron microscopy (SEM) (FIGS.
43-44), Raman spectroscopy (FIG. 45), x-ray photoelectron
spectroscopy (XPS) (FIG. 46) and transmission electron microscopy
(TEM) (FIGS. 47-48). The overall results of the characterization
experiments show that the embedded PAMAM particles of the MDP-G1
membrane can serve as supramolecular containers for Pt(0)
nanoparticles (2-3 nm).
[0365] To study the catalytic activity of Pt(0) loaded MDP-G1
membrane, experiments were carried out to measure the
regioselective hydrogenation of alkenes and alkynes [53].
Regioselective hydrogenation is an important reaction of the
synthesis of special chemicals and pharmaceuticals 1531. For the
catalytic experiments, a Pt(0) loaded MDP-G1 membrane (FIG. 40) was
cut into small pieces and loaded into a customer-built stainless
reactor. The reactor was then loaded with a methanol solution
containing the dissolved unsaturated compounds. Hydrogen gas (2
bar) was then continuously fed to the reactor at room. .sup.1H NMR
and gas chromatography (GC) were utilized to measure the conversion
and extent of reaction. To evaluate the recyclability of the Pt(0)
loaded MDP-G1 membrane, hydrogen gas to regenerate the membrane by
reducing the oxidized and bound Pt.sup.4+ ions to Pt(0). FIGS.
49-50 summarize the results of the catalytic experiments. The
overall results of these experiments show the Pt(0) loaded MDP-G1
membrane can serve as a recyclable catalytic membrane for the
regioselective hydrogenation of hydrogenation of alkenes and
alkynes.
Example 10
Mixed Matrix Membranes with In Situ Synthesized Dendrimer Particles
as Supercontainers for Cu(O)
[0366] Cu(0) is a leading metal for the preparation of catalysts
for the electrochemical reduction of CO.sub.2 to liquid fuels and
valuable products [54, 55]. Although higher generation PAMAM
dendrimers (e.g. G4-G6 NH.sub.2) have shown excellent potential as
templates for the preparation of Cu(0) DENs, they are expensive due
to the multiple steps required for their synthesis and
purification. Because of this, Cu(0) DENs have remained for the
most par "laboratory" model systems with no prospects for
utilization as catalysts and electrocatalysts for SuChEM related
applications.
[0367] Reactive encapsulation process was used to prepare our new
families of PVDF UF membranes with in-situ synthesized PAMAM
supramolecular containers for Cu(0) (FIG. 51). Similar to the
methods described in Examples 1-6 and Example 9, the PVDF UF
membrane with in-situ generated PAMAM dendrimer particles (MDP-G0)
using a G0-NH.sub.2 PAMAM dendrimer as particle precursor was
utilized. The Cu(0) loaded MDP-G1 membrane was characterized by
scanning electron microscopy (SEM) (FIG. 52), Raman spectroscopy
(FIG. 53), x-ray photoelectron spectroscopy (XPS) (FIG. 54) and
transmission electron microscopy (TEM) (FIG. 55-56). The overall
results of the characterization experiments show that the embedded
PAMAM particles of the MDP-G1 membrane can serve as supramolecular
containers for Cu(O) nanoparticles (2-3 nm).
[0368] The examples set forth above are provided to give those of
ordinary skill in the art a complete disclosure and description of
how to make and use the embodiments polymeric membranes with
embedded dendrimer-like polymeric micro/nanoparticles and related
methods and systems of the disclosure, and are not intended to
limit the scope of what the Applicants regard as their disclosure.
Modifications of the above-described modes for carrying out the
disclosure can be used by persons of skill in the art, and are
intended to be within the scope of the following claims.
[0369] The entire disclosure of each document cited (including
patents, patent applications, journal articles, abstracts,
laboratory manuals, books, or other disclosures) in the Background,
Summary, Detailed Description, and Examples is hereby incorporated
herein by reference. All references cited in this disclosure are
incorporated by reference to the same extent as if each reference
had been incorporated by reference in its entirety individually.
However, if any inconsistency arises between a cited reference and
the present disclosure, the present disclosure takes
precedence.
[0370] The terms and expressions which have been employed herein
are used as terms of description and not of limitation, and there
is no intention in the use of such terms and expressions of
excluding any equivalents of the features shown and described or
portions thereof, but it is recognized that various modifications
are possible within the scope of the disclosure claimed Thus, it
should be understood that although the disclosure has been
specifically disclosed by preferred embodiments, exemplary
embodiments and optional features, modification and variation of
the concepts herein disclosed can be resorted to by those skilled
in the art, and that such modifications and variations are
considered to be within the scope of this disclosure as defined by
the appended claims.
[0371] It is also to be understood that the terminology used herein
is for the purpose of describing particular embodiments only, and
is not intended to be limiting. As used in this specification and
the appended claims, the singular forms "a," "an," and "the"
include plural referents unless the content clearly dictates
otherwise. The term "plurality" includes two or more referents
unless the content clearly dictates otherwise. Unless defined
otherwise, all technical and scientific terms used herein have the
same meaning as commonly understood by one of ordinary skill in the
art to which the disclosure pertains.
[0372] When a Markush group or other grouping is used herein, all
individual members of the group and all combinations and possible
subcombinations of the group are intended to be individually
included in the disclosure. Every combination of components or
materials described or exemplified herein can be used to practice
the disclosure, unless otherwise stated. One of ordinary skill in
the art will appreciate that methods, device elements, and
materials other than those specifically exemplified can be employed
in the practice of the disclosure without resort to undue
experimentation. All art-known functional equivalents, of any such
methods, device elements, and materials are intended to be included
in this disclosure. Whenever a range is given in the specification,
for example, a temperature range, a frequency range, a time range,
or a composition range, all intermediate ranges and all subranges,
as well as, all individual values included in the ranges given are
intended to be included in the disclosure. Any one or more
individual members of a range or group disclosed herein can be
excluded from a claim of this disclosure. The disclosure
illustratively described herein suitably can be practiced in the
absence of any element or elements, limitation or limitations which
is not specifically disclosed herein.
[0373] A number of embodiments of the disclosure have been
described. The specific embodiments provided herein are examples of
useful embodiments of the disclosure and it will be apparent to one
skilled in the art that the disclosure can be carried out using a
large number of variations of the devices, device components,
methods steps set forth in the present description. As will be
obvious to one of skill in the art, methods and devices useful for
the present methods can include a large number of optional
composition and processing elements and steps.
[0374] In particular, it will be understood that various
modifications may be made without departing from the spirit and
scope of the present disclosure. Accordingly, other embodiments are
within the scope of the following claims.
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