U.S. patent application number 12/367984 was filed with the patent office on 2010-08-12 for novel multifunctional azo initiators for free radical polymerizations: methods of preparation.
Invention is credited to Jeffrey M. Atkins, Pious V. Kurian, John D. Morris, William J. Ward.
Application Number | 20100204361 12/367984 |
Document ID | / |
Family ID | 42145087 |
Filed Date | 2010-08-12 |
United States Patent
Application |
20100204361 |
Kind Code |
A1 |
Kurian; Pious V. ; et
al. |
August 12, 2010 |
NOVEL MULTIFUNCTIONAL AZO INITIATORS FOR FREE RADICAL
POLYMERIZATIONS: METHODS OF PREPARATION
Abstract
The invention provides compositions of matter, methods of their
synthesis, and methods of their use in polymerization reactions.
The compositions include polyfunctional initiators used to make
star polymers when polymerized with monomers. The polyfunctional
initiators are synthesized out of a multifunctional core with at
least two functional groups and two or more initiator units bonded
to the functional groups. The initiator units have two
electron-withdrawing groups bonded to a central carbon atom and an
azo group between the central carbon atom and the functional group.
The polyfunctional initiators are particularly effective because
when they decompose to form the radical core of a star polymer, the
electron-withdrawing groups prevent the corresponding radical from
forming any linear polymer contamination and only desired star
polymers result.
Inventors: |
Kurian; Pious V.; (Aurora,
IL) ; Atkins; Jeffrey M.; (Aurora, IL) ;
Morris; John D.; (Aurora, IL) ; Ward; William J.;
(Glen Ellyn, IL) |
Correspondence
Address: |
NALCO COMPANY
1601 W. DIEHL ROAD
NAPERVILLE
IL
60563-1198
US
|
Family ID: |
42145087 |
Appl. No.: |
12/367984 |
Filed: |
February 9, 2009 |
Current U.S.
Class: |
523/336 ;
534/739 |
Current CPC
Class: |
C08F 220/281 20200201;
C08F 222/1006 20130101; C09B 29/00 20130101; C08F 220/34 20130101;
C08F 4/04 20130101; C08F 220/56 20130101; C08F 2/32 20130101 |
Class at
Publication: |
523/336 ;
534/739 |
International
Class: |
C08J 3/02 20060101
C08J003/02; C09B 29/00 20060101 C09B029/00 |
Claims
1. A polyfunctional initiator comprising a multifunctional core
bonded to at least two initiator units wherein each initiator unit
comprises at least one radical stabilizing group bonded to a
central atom and an azo group between the central atom and the
multifunctional core.
2. The polyfunctional initiator of claim 1 wherein the at least one
radical stabilizing group is one selected from the list consisting
of: an electron-withdrawing group, a steric hindrance group, and
any combination thereof.
3. The polyfunctional initiator of claim 1 wherein the central atom
is selected from the list consisting of: carbon, oxygen, and
silicon.
4. The polyfunctional initiator of claim 1 wherein the
multifunctional core comprises at least two end atoms; each end
atom is bonded to an initiator unit, the atom of each end atom is
selected from the list consisting of carbon, oxygen, nitrogen,
primary amine nitrogen, secondary amine nitrogen, tertiary amine
nitrogen, sulfur, silicon, and siloxane silicon; the
multifunctional core spans at least one string with a string length
of between 1 and 200 atoms between each end atom not including the
end atoms; the atoms within the string comprise at least one item
selected from the list consisting of saturated carbon, unsaturated
carbon, carbonyl carbon, saturated nitrogen, unsaturated nitrogen,
and oxygen.
5. The polyfunctional initiator of claim 3 further comprising
between 1 and 4 branching atoms, each branching atom is an atom
within at least three different strings, and is selected from the
list consisting of carbon, nitrogen, and silicon.
6. The polyfunctional initiator of claim 1 according to formula I:
##STR00006## wherein: R is a multifunctional core with at least two
functional groups, R.sub.1 is a linker group selected from the list
consisting of: one or more carbons, an amide, an ester, an amine, a
silane, sulfur, silicon, a thiol, an ether, and any combination
thereof R.sub.2 is a hydrocarbon having between 4 and 100 carbon
atoms having a structure selected from the list consisting of
linear, branched, aromatic, and aliphatic, at least one of R.sub.3
and R4 are radical stabilizing groups, R.sub.5 is hydrocarbon
having between 1 and 50 carbon(s) or a radical stabilizing group,
and X is greater than 1.
7. The polyfunctional initiator of claim 1 wherein the
multifunctional core is one selected from the list consisting of:
2,2',2''-Nitrilotriethylamine, triethanol amine, pentaerythritol
and its derivatives, dendritic molecules, multifunctional amines,
multifunctional acid chlorides, multifunctional esters,
multifunctional acids, and multifunctional alcohols.
8. The polyfunctional initiator of claim 6 wherein R.sub.2 is
selected from the list consisting of a linear substituted alkyl
group, a non-linear substituted alkyl group, a linear unsubstituted
alkyl group, a non-linear unsubstituted alkyl group, a linear
substituted aryl group, a non-linear substituted aryl group, a
linear unsubstituted aryl group, a non-linear unsubstituted aryl
group, a linear substituted cyclo alkyl group, a non-linear
substituted cyclo alkyl group, a linear unsubstituted cyclo alkyl
group, and a non-linear unsubstituted cyclo alkyl group.
9. The polyfunctional initiator of claim 6 wherein R.sub.5 is
selected from the list consisting of: a linear alkyl group, a
non-linear alkyl group, an aryl group, an electron withdrawing
group, and any combination thereof.
10. The polyfunctional initiator of claim 5 wherein at least one of
the electron withdrawing groups are selected from the list
consisting of CN, CONR.sub.6R.sub.7, COOR.sub.8, COOH, NO.sub.2,
CF.sub.3, and --C.sub.6H.sub.4,R.sub.9 wherein: R.sub.6, R.sub.7,
and R.sub.8 are each one selected from the list consisting of
hydrogen, a linear alkyl group, a linear aryl group, a linear
alkoxy group, a linear amino group, a linear alkylamino group, a
linear hydroxyl group, a branched alkyl group, a branched aryl
group, a branched alkoxy group, a branched amino group, a branched
alkylamino group, and a branched hydroxyl group and R.sub.9 is
selected from the group consisting of CN, CONR.sub.6R.sub.7,
COOR.sub.8, COOH, NO.sub.2, and CF.sub.3.
11. The polyfunctional initiator of claim 1 constructed and
arranged for use in a free radical polymerization reaction selected
from the list consisting of: solution, suspension, bulk, emulsion,
inverse emulsion, precipitation/dispersion, inverse suspension, and
any combination thereof.
12. A method of synthesizing a star polymer comprising the steps
of: providing at least one 4-functional peroxide initiator having a
multifunctional core and 4 initiator units, providing a plurality
of monomers, decomposing at least two initiator units to form at
least one initiator radical, and initiating a polymerization
reaction between each of the at least one initiator radicals and
the plurality of monomers.
13. The polyfunctional initiator of claim 12 constructed and
arranged for use in a free radical polymerization reaction selected
from the list consisting of: solution, suspension, bulk, emulsion,
inverse emulsion, precipitation/dispersion, inverse suspension, and
any combination thereof.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] None.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not Applicable.
BACKGROUND OF THE INVENTION
[0003] The present invention relates to synthesis of thermolabile
multifunctional azo compounds and their use for the preparation of
high molecular weight well-defined structured polymers. As
described for example in U.S. Pat. Nos. 6,605,674, 6,627,719, and
6,753,388 these azo compounds are particularly useful for the
synthesis of flocculants, coagulants and dispersants for paper,
mining and wastewater industries.
[0004] Well-defined macromolecular architectures are typically
prepared by living anionic or cationic polymerization or by
controlled radical polymerizations such as RAFT (Reversible
addition-fragmentation chain transfer), ATRP (Atom Transfer Radical
Polymerization), NMP (Nitroxide-Mediated Polymerization) and more
recently SET-LRP (Single Electron Transfer-Living Radical
Polymerization). Each of these methods have limitations, such as
monomer compatibility, purity of reactants, reaction medium, heavy
metal contamination in the final product, longer reaction times,
and an inability to achieve high molecular weights. From an
industrial point of view these polymerizations are not enticing due
to the processing cost and selectivity towards monomers and
reaction conditions. Traditional free radical polymerization is
widely used industrially for polymer synthesis, due to the ease of
synthesis and the ability to avoid the limitations of the prior
methods. However, the ability to control the concise architecture
of the final product using traditional free radical methods is
limited.
[0005] There are many ways to manipulate the architecture of
macromolecules. Star polymers gained much attention in the last two
decades and there have been numerous publications on its synthesis
and properties of the resulting polymers. The two most common ways
to make star polymers are (1) start with a multifunctional
initiator (as shown in FIG. 1) and (2) covalently attach a
preformed polymer to a polyfunctional core. Polyfunctional
initiators result in polymers of high molecular weights and in the
synthesis of very large macromolecules (MW several millions) the
first route is the preferred method of preparation.
[0006] Synthesis of linear macromolecules from azo initiators are
widely known and have been practiced for many years. AIBN
(Azobisisobutyronitrile) is one of the most commonly used initiator
molecule in the industry and academia due to its cost,
availability, solubility and decomposition temperature. Upon
decomposition a molecule such as AIBN generates a molecule of
N.sub.2 and two equally reactive radicals capable of initiating
polymerization, which could lead to two linear polymers. There are
numerous publications available on the manipulation of azo groups
to gain better control on the final architecture of the
macromolecule. Several detailed reviews on azoderivatives are
available in the literature; especially reviews by C. I. Simionescu
et al. covers most of the work done in this area. (Prog. Polym.
Sci., 1986, 12, 1-109; Romanian chemical quarterly reviews 1995;
3(2), 83-103).
[0007] There are very few useful multifunctional initiators capable
of initiating polymerization. The main drawback with
multifunctional initiators is that upon decomposition, a second
radical produces linear polymers in addition to the desired star
polymers. For example, (as illustrated in FIG. 3) a prior art
composition commercially known as Arkema's Luperox JWEB50 is a
multifunctional (four functional) organic peroxide, which upon
decomposition yields a tetra functional initiator and four
tertbutoxy radicals which each could produce linear polymers.
(Penlidis et al,: Poly Bull 2006, 57, 157-167 and Penlidis et al:
Macromol Chem Phys 2003, 204, 436-442). In order to exclusively
make structured polymer these tertbutoxy radicals need to be
prevented from initiating polymerization reactions.
[0008] U.S. Pat. No. 4,929,721 teaches the preparation of azo side
groups on the polymer backbone by copolymerization. The azo groups
on the resulting polymer may be used for post modification of the
polymer. The azo groups reported by this patent have two main
problems; first, the decomposition temperature of this molecule is
too high to be practically used as a polymerization initiator for
inverse emulsion polymerization. Their objective was to keep this
molecule stable during polymerization and activate only for post
modification. This patent reports their compounds to be very stable
at 130.degree. C. The second problem with this approach is that
this will also create the linear polymers in addition to graft
copolymers.
[0009] International Patent Application WO/0224773 teaches the
synthesis of branched polymers. In this teaching they have taken
into account of the fact there could be linear polymers formed.
This was eliminated by making sure the second radical is unable to
initiate the polymerization. However, this teaching also fails to
make well-defined cores to make well-defined star polymers. Both of
the above teachings makes use of the vinyl groups to homo or
co-polymerize the azo groups onto a polymer and the azo groups are
activated at a later time for further modification of the polymer
or at the same time to make highly random branches. Activation of
the azo side groups at the same time as the backbone synthesis will
lead to highly branched but a poorly defined architecture. This
approach in flocculent synthesis will result in highly closed
architecture, which are known to be very ineffective.
[0010] The art described in this section is not intended to
constitute an admission that any patent, publication or other
information referred to herein is "prior art" with respect to this
invention, unless specifically designated as such. In addition,
this section should not be construed to mean that a search has been
made or that no other pertinent information as defined in 37 C.F.R.
.sctn.1.56(a) exists.
BRIEF SUMMARY OF THE INVENTION
[0011] At least one embodiment is directed towards a polyfunctional
initiator comprising a multifunctional core bonded to at least two
initiator units. Each initiator unit comprises two
electron-withdrawing groups bonded to a central carbon atom and an
azo group between the central carbon atom and the multifunctional
core.
[0012] At least one embodiment is directed to a polyfunctional
initiator in which the multifunctional core comprises at least two
end atoms. Each end atom is bonded to an initiator unit. The atom
of each end atom is selected from the list consisting of oxygen,
carbon, and nitrogen. The multifunctional core spans at least one
string with a string length of between 2 and 100 atoms between each
end atom not including the end atoms. The atoms within the string
are selected from the list consisting of oxygen, carbon, and
nitrogen.
[0013] At least one embodiment is directed to a polyfunctional
initiator in which the multifunctional core further comprises
between 1 and 4 branching atoms. Each branching atom is an atom
within at least three different strings. Each branching atom is
engaged at all of its binding sites to other atoms within a string
and is selected from the list consisting of carbon and
nitrogen.
[0014] One architecture of the polyfunctional initiator is
according to Formula I:
##STR00001##
wherein: [0015] R is a multifunctional core with at least two
functional groups, R.sub.1 is a linker group selected from the list
consisting of: an amide whose carbonyl group is attached to
nitrogen and is attached to R.sub.2 by the nitrogen; an ester whose
carbonyl group is attached to oxygen and is attached to the R.sub.2
by the nitrogen; and an ether group in which the oxygen is attached
to R.sub.2, R.sub.2 is a hydrocarbon having between 4 and 20 carbon
atoms. At least one of R.sub.3 and R.sub.4 are an
electron-withdrawing group. One of R.sub.3 and R.sub.4 can be an
electron donating group. R.sub.5 is hydrocarbon having between 1
and 50 carbon(s); and X is greater than 1.
[0016] The multifunctional core R can be one selected from the list
consisting of: 2, 2', 2''-Nitrilotriethylamine, triethanol amine,
pentaerythritol and its derivatives, dendritic molecules,
multifunctional amines, multifunctional acid chlorides,
multifunctional carbonyls, multifunctional esters, and
multifunctional alcohols. R.sub.1 can be selected from the list
consisting of: two or more alkyl groups, two or more aryl groups,
and alkyl and an aryl group as well as a linear substituted alkyl
group, a non-linear substituted alkyl group, a linear unsubstituted
alkyl group, a non-linear unsubstituted alkyl group, a linear
substituted aryl group, a non-linear substituted aryl group, a
linear unsubstituted aryl group, a non-linear unsubstituted aryl
group, a linear substituted cyclo alkyl group, a non-linear
substituted cyclo alkyl group, a linear unsubstituted cyclo alkyl
group, and a non-linear unsubstituted cyclo alkyl group.
[0017] In at least one embodiment, at least one of the electron
withdrawing groups are selected from the list consisting of CN,
CONR.sub.6R.sub.7 and COOR.sub.8 wherein: R.sub.6, R.sub.7, and
R.sub.8 are each one selected from the list consisting of hydrogen,
a linear alkyl group, a linear aryl group, a linear alkoxy group, a
linear amino group, a linear alkylamino group, a linear hydroxyl
group, a branched alkyl group, a branched aryl group, a branched
alkoxy group, a branched amino group, a branched alkylamino group,
and a branched hydroxyl group. In addition, R.sub.5 can be selected
from the list consisting of: a linear alkyl group, a non-linear
alkyl group, an aryl alkyl group, a non-linear aryl group, and any
combination thereof.
[0018] At least one embodiment is directed towards a method of
synthesizing a polyfunctional initiator comprising the steps of:
synthesizing two or more initiator units; synthesizing one or more
multifunctional cores each having more than one functional group;
and coupling each functional group to an initiator unit. In at
least one embodiment the initiator units comprise two
electron-withdrawing groups bonded to a central carbon atom and an
azo group between the central carbon atom and the multifunctional
core. The step of synthesizing two or more initiator units further
comprises the steps of: diazotization of an aryl amine; reacting
the diazotized aryl amine with an alkyl malonitrile to form an
aromatic diazo compound; and converting the carboxylic acid into an
acid chloride. In at least one embodiment the aryl amine is formed
from reacting 3-Aminobenzoic acid with sodium nitrite to form a
diazonium ion.
[0019] In some embodiments the alkyl malonitrile is isopropyl
malonitrile. In some embodiments the acid is converted into an acid
chloride using PCl.sub.5, the halide is chlorine and the synthesis
further comprises the step of: replacing the bond connecting the
halide atom to the acid with a bond connecting the functional group
to the acid, and the functional group is an alcohol, an amine, or a
sulfur based group.
[0020] At least one embodiment is directed towards a method of
synthesizing a polymer comprising the steps of: providing at least
one polyfunctional initiator comprising a multifunctional core
bonded to at least two initiator units wherein each initiator unit
comprises two electron-withdrawing groups bonded to a central
carbon atom and an azo group between the central carbon atom and
the multifunctional core, providing a plurality of monomers, and
reacting the at least one polyfunctional initiator and plurality of
monomers in a radical polymerization reaction.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] A detailed description of the invention is hereafter
described with specific reference being made to the drawings in
which:
[0022] FIG. 1 is an illustration of the synthesis of a star
polymer.
[0023] FIG. 2 is an illustration of the decomposition of a star
initiator.
[0024] FIG. 3 is an illustration of a PRIOR ART star initiator.
[0025] FIG. 4 is a graph illustrating star polymer
performances.
[0026] FIG. 5 is a graph illustrating star polymer
performances.
[0027] FIG. 6 is a graph illustrating star polymer
performances.
[0028] FIG. 7 is a graph illustrating dual feed polymer
performances.
[0029] FIG. 8 is an illustration of a PRIOR ART polymer feed
apparatus.
[0030] FIG. 9 is an illustration of a dual dosage polymer feed
apparatus.
DETAILED DESCRIPTION OF THE INVENTION
[0031] For purposes of this application the definition of these
terms is as follows:
[0032] "Architecture" means the sequential arrangement of
constituent groups of a polymer, which results in the degree to
which a polymer is linear, branched, structured, starred, or any
combination thereof.
[0033] "Branching Atom" means an atom within two or more strings
that is bonded to more than two atoms counted in a string.
[0034] "Floc" means a mass formed in a fluid through precipitation
or aggregation of suspended particles.
[0035] "Initiator" means a composition of matter that initiates a
radical polymerization reaction upon thermal decomposition.
[0036] "Initiator Unit" means that portion of a polyfunctional
initiator that is bound to the multifunctional core and is capable
of initiating a radical polymerization reaction upon thermal
decomposition.
[0037] "Hindrance Group" means a group that sterically impairs the
ability of a monomer to react with a radical.
[0038] "Multifunctional" means having two or more arms or arm
supporting regions.
[0039] "3-Functional Initiator" means an initiator having 3
arms.
[0040] "4-Functional Initiator" means an initiator having 4
arms.
[0041] "5-Functional Initiator" means an initiator having 5
arms.
[0042] "6-Functional Initiator" means an initiator having 6
arms.
[0043] "N-Functional Initiator" means an initiator having a number
of arms equal to the integer N.
[0044] "Multifunctional Core" means a structural portion of a
polyfunctional initiator bound to or capable of binding to two or
more initiators. The multifunctional core comprises two or more
functional groups and each functional group can bind one initiator
to the core.
[0045] "4-Functional Peroxide Initiator" means an initiator having
4 arms according to the structure illustrated in FIG. 3 where D
represents one or more atoms. Luperox Jweb50 by Arkema is an
example of a 4-Functional Peroxide Initiator.
[0046] "Polyfunctional Initiator" means a composition of matter
containing two or more sites capable of initiating a radical
polymerization reaction after thermal decomposition, which then
anchor a repeating polymer chain. A polyfunctional initiator
comprises at least one multifunctional core and two or more
initiator units. A polyfunctional initiator may have more than one
kind of initiator unit.
[0047] "Stable Radical" means a composition of matter having a
radical site formed after thermal decomposition, which is
substantially incapable of initiating a radical polymerization
reaction due to the effects of one or more stabilizing groups in
the composition of matter.
[0048] "String" means the smallest set of consecutive
interconnected atoms (not including hydrogen) between two points on
a molecule or between two points on a portion of a molecule, and
does not include branched deviations from that set. The "string"
between end atom A and end atom Z (which does not include A and Z
in the count) in the following molecule has a length of 6:
##STR00002##
[0049] Any atom within a string can be in more than one string, so
branching atom B is within 4 strings (AZ, AM, JZ and JM).
[0050] "String Length" means the number of atoms in a string.
[0051] "Second Structuring Agent" means a structuring agent other
than an initiator.
[0052] "Structuring Agent" means a composition of matter, which
facilitates the interconnection of linear polymers to form
structured polymers.
[0053] "Structured Polymer" means a polymer comprising two or more
linear chains with two or more cross linkages interconnecting the
linear chains.
[0054] In the event that a description of a term stated elsewhere
in this application is inconsistent with a meaning (explicit or
implicit) which is commonly used, in a dictionary, or stated in a
source incorporated by reference into this application, the
application and the claim terms in particular are understood to be
construed according to the description stated in this application,
and not according to the common definition, dictionary definition,
or the definition that was incorporated by reference.
[0055] Referring now to FIG. 1 there is shown a 4-Functional
Initiator star initiator (1) comprising a multifunctional core (2)
bound to 4 initiator units (3). When polymerized with monomer units
a repeating chain (4) becomes anchored at each initiator unit (3).
A star polymer (5) results from the extension of a repeating chain
(4) being bound to multiple initiator units (3). Some examples of
uses of star initiators are found in the co-pending, commonly
owned, simultaneously filed application titled "Novel
Multifunctional Azo Initiators for Free Radical Polymerizations:
Uses Thereof" having an attorney docket number of 8184.
[0056] Embodiments of the present invention relate to the synthesis
of novel multifunctional azo initiators and the polymerization of
structured polymers and copolymers of high molecular weight from
these initiators. Embodiments of the invention are directed towards
structured polymers obtained from radical polymerizations using
initiators according to formula I:
##STR00003##
[0057] Wherein R is a multifunctional core such as,
2,2',2''-Nitrilotriethylamine, triethanol amine, pentaerythritol
and its derivatives, or dendritic molecules with multiple
functional groups. The number of arms of the resulting polymer
depends on the number of functional group present in the core. The
most common core groups are multifunctional amines, acid chlorides
or alcohols.
[0058] R.sub.1 is a linker group such as an amide, an ester, or an
ether group. In at least one embodiment R.sub.1 is an amide group
having one or more carbon atoms, the endmost carbon atom being part
of a carbonyl group attached to a nitrogen atom. R.sub.1 is engaged
by one of the one or more carbon atoms to R. R.sub.1 is engaged to
R.sub.2 by the nitrogen atom. In at least one embodiment, R.sub.1
is positioned within the initiator according to the following
formula where R.sub.X represents a carbon bearing group:
##STR00004##
[0059] In at least one embodiment R.sub.1 is an ester group having
one or more carbon atoms, the endmost carbon atom being part of a
carbonyl group single bonded to an oxygen atom. R.sub.1 is engaged
by one of the one or more carbon atoms to R. R.sub.1 is engaged to
R.sub.2 by the single bonded oxygen atom. In at least one
embodiment, R.sub.1 is positioned within the initiator according to
the following formula where R.sub.X represents a carbon bearing
group:
##STR00005##
[0060] In at least one embodiment R.sub.1 is an ether group having
one or more carbon atoms, the endmost carbon atom being attached to
an oxygen atom. R.sub.1 is engaged by one of the one or more carbon
atoms to R. R.sub.1 is engaged to R.sub.2 by the oxygen atom. In at
least one embodiment, R.sub.1 is positioned within the initiator
according to the following formula where R.sub.X represents 1 or
more carbon atoms:
--R--R.sub.X--O--R.sub.2--
[0061] R.sub.2 represent linear and non-linear, substituted or
non-substituted alkyl, aryl or cyclo-alkyl having 4 to 20 C atoms.
R.sub.3 and R.sub.4 can be same or different. At least one of
R.sub.3 and R.sub.4 are electron withdrawing groups including but
not limited to CN, CONR.sub.6R.sub.7 or COOR.sub.8 wherein R.sub.6,
R.sub.7, and R.sub.8 are individually similar or dissimilar, and
represent hydrogen, or a linear or branched alkyl, aryl group,
alkoxy, amino, alkylamino, or hydroxyl groups or similar groups.
One of R.sub.3 and R.sub.4 can be an electron depositing group.
R.sub.5 represents linear or structured alkyl or aryl groups having
1 to 50 carbons and X is greater than or equal to 2.
[0062] As illustrated in FIG. 2, when the initiator (3) is heated
it can thermally decompose, releasing a N.sub.2 molecule and two
radical containing units (7, 8). One of the units (8) contains
functional groups (6) capable of stabilizing the radical-containing
species, preventing it from initiating a polymerization reaction.
The second radical containing unit (7) receives no such
stabilization, and is capable of initiating a polymerization
reaction in a monomer solution. As that unit (7) containing the
active radical species is bound to a multifunctional core,
polymerization is only initiated from units bound to the
multifunctional core. As the multifunctional core contains two or
more initiators, and upon thermal decomposition the only active
radical species that could be formed are bound to the
multifunctional core, the resultant polymer will be a star
polymer.
[0063] In at least one embodiment, one or more of the stabilizing
groups (6) are electron-withdrawing groups, which reduce the
reactivity of the stable radical (8). The electron withdrawing
groups can be engaged to a central atom. If the central atom is a
carbon, there can be 1-3 electron-withdrawing groups. In at least
one embodiment, an electron-withdrawing group is selected from the
list consisting of CN, CONR.sub.6R.sub.7, COOR.sub.8, COOH,
NO.sub.2, and CF.sub.3. In at least one embodiment, the
electron-withdrawing group comprises an aryl group engaged to the
central atom and one item selected from the same list engaged to
the aryl group.
[0064] In at least one embodiment, one or more of the stabilizing
groups (6) are large steric hindrance groups. A steric hindrance
group is a bulky group that either covers the radical site of the
stable radical, or sufficiently blocks monomer access to the
radical site thereby preventing the radical from reacting with
monomers to form linear polymers. In at least one embodiment, the
steric hindrance group can be selected from the list of: linear,
branched, aromatic, aliphatic groups, and any combination thereof
that include between 4 and 100 carbon atoms. The steric hindrance
group can comprise carbon, silicon, oxygen, sulfur, and any
combination thereof.
[0065] In at least one embodiment, the multifunctional core
comprises at least one string extending between two end atoms. Each
end atom is bonded to an initiator unit. When the multifunctional
core thermally decomposes, the initiator radical remains engaged to
the end atom while the stable radical is detached. The string
comprises atoms selected form the list consisting of oxygen,
nitrogen, carbon, sulfur, silicon, and any combination thereof The
string atoms may be in the form of siloxane, carbonyl, amine
(primary, secondary, and tertiary) groups, and may themselves be
engaged to other groups as well. The string may span from 2 to 100
atoms between each end atom not including the end atoms. In at
least one embodiment, the end atom is bonded to a nitrogen atom
that will become part of the generated N.sub.2 molecule when the
initiator decomposes.
[0066] In embodiments in which the multifunctional core comprises
more than two initiator units, the string also comprises branching
atoms. The branching atoms are bonded to three or more non-hydrogen
atoms, and lie along more than one string. When there is more than
one initiator, for each initiator unit there is at least one string
extending between end atoms. The branching atoms can be saturated
or unsaturated. The multifunctional core may comprise chains of
atoms that are not strings extending between initiator units.
Multifunctional cores may have each string run through a single
branching atom, or there may be branching atoms which branch off
from other branching atoms thereby having branching atoms through
which not every string passes. Branching atoms may comprise any
atom capable of bonding three or more other atoms. The end atoms
may be nitrogen, oxygen, silicon, carbon, or any atom capable of
bonding two other atoms.
[0067] The following examples are presented to describe embodiments
and utilities of the invention and are not meant to limit the
invention unless otherwise stated in the claims.
EXAMPLES
1) Initiator Synthesis
[0068] In at least one embodiment, the initiator unit was
synthesized from various components. Initiators having 2, 3, 4, 5,
6, and any number of initiator units are contemplated by this
invention. The number of initiator units on each initiator depends
on the multifunctional core that the initiator is formed with.
[0069] In one embodiment, the multifunctional azo initiator was
formed using a convergent synthetic route, in which the initiator
unit was synthesized, and then coupled to a multifunctional core.
3-(Azoisopropyl-malonitrile) benzoic acid was formed in yields
greater than 95% through the diazotization of an aryl amine.
3-Aminobenzoic acid was treated with sodium nitrite to form a
diazonium ion, which was then reacted with isopropyl malonitrile in
the presence of sodium acetate to form the unsymmetrical azo
initiator. Isopropylmalonitrile was synthesized via literature
methods. (Dunham, J. C.; Richardson, A. D.; Sammelson, R. E.,
Synthesis 2006, (4), 680-686, Sammelson, R. E.; Allen, M. J.
Synthesis 2005, (4), 543-546).
[0070] In at least one embodiment, the multifunctional azo
initiator is formed by first converting the acid into the acid
chloride using PCl.sub.5. 3-(Azoisopropylmalonitrile)benzoyl
chloride readily forms esters or amides when reacted with alcohols
or amines under standard reaction conditions.
2) 3-(Azoisopropylmalonitrile)benzoic acid
[0071] Concentrated HCl (96.4g) was slowly added to a solution of
100.4 g of 3-aminobenzoic acid (3-ABA) in 1.98 L of H.sub.2O in a
5L reactor, fitted with a mechanical stirrer and a thermometer, and
stirred until the 3-ABA was dissolved. The solution was cooled to
3.degree. C. on an ice bath, and then a chilled solution of 50.5 g
of NaNO.sub.2 in 410 mL H.sub.2O was added quickly. The temperature
of the reaction mix rose to 7.degree. C., and a white precipitate
began to form. After 15 minutes, a chilled solution of 87.0 g of
isopropylmalonitrile, 78.0 g of sodium acetate in 710 mL of EtOH
and 600 mL of H.sub.2O are added to the reaction mix. A slight
temperature rise (5-10.degree. C.) was observed again. A thick
yellow solid precipitated from the solution within 5 minutes. After
45 minutes, the product was filtered off, washed with a small
amount of chilled H.sub.2O, and dried for 72 hours under vacuum to
give 183.1 g (98%) of 3-((isopropylmalonitrile)diazo)-benzoic acid.
The structure was confirmed by .sup.13C NMR and .sup.1H NMR.
3) 3-(Azoisopropylmalonitrile)benzoyl chloride
[0072] 43.5 g of PCl.sub.5 was added to a cooled solution
(4.degree. C., ice bath) of 50 g of
3-((isopropylmalonitrile)diazo)benzoic acid in 600 mL of
CH.sub.2Cl.sub.2. The temperature rose slightly to 10.degree. C.
The mix was allowed to stir for 2 hours at 4.degree. C., then
another 2 hours at room temperature. The solution was concentrated
50%, and 300 mL of hexanes was added. The precipitate was removed
from the mix by filtration, and the solution was concentrated to
dryness to give 51.16 g of a dark brown oil (95%) of the acid
chloride, which was used without any other further purification.
The structure was confirmed by .sup.13C NMR and .sup.1H NMR.
4) 3-Arm Star Initiator
[0073] A cooled solution containing 1.34 g of NEt.sub.3 and 0.59 g
of tris(2-aminoethyl)amine in 30 mL of CH.sub.2Cl.sub.2 was added
to a solution of 3.30 g of 3-((isopropylmalonitrile)diazo)benzoyl
chloride in 50 mL of CH.sub.2Cl.sub.2 at 3.degree. C. under an
N.sub.2 atmosphere. The mix was stirred for 3 hours, and then
quenched with 60 mL of brine. The aqueous layer was separated and
washed twice with 30 mL of CH.sub.2Cl.sub.2. The combined organic
layers was dried with Na.sub.2SO.sub.4, filtered, and concentrated
under vacuum to give 3.29 g of a yellow solid. The structure was
confirmed by .sup.13C NMR and .sup.1H NMR.
5A) Inverse Emulsion Polymerization
[0074] Preparation of Acrylamide/Dimethylaminoethyl Acrylate Methyl
chloride Quaternary Salt (50/50) copolymers.
[0075] An aqueous monomer phase was made up dissolving 9.82 g
Adipic acid (Sigma-Aldrich, St. Louis, Mo.) and 34.78 g DI water in
227.74 g of 49.5% aqueous solution of Acrylamide (Nalco Company,
Naperville, Ill.). The components were stirred until a homogenous
solution was formed. To this solution added 0.1 g of EDTA followed
by 384.084 g Dimethylaminoethyl acrylate methylchloride (DMAEA-MCQ,
SNF Riceboro, Ga.) and mixed well. An oil phase was prepared from
274.96 g of hydrocarbon solvent (Exxon Chemical Company, Houston,
Tex.), 14.1 g Arlacel SOAC (Uniqema, New Castle, Del.) and 16.3 g
Tween 85 (Uniqema, New Castle, Del.) at room temperature. Oil phase
was added to a 1500 mL reactor set at 40.degree. C. When oil phase
addition was complete rate of mixing was increased from 500 rpm to
1000 rpm and added the monomer phase slowly into the oil phase. The
mixing was accomplished by a 10 mm rod with a Teflon paddle at the
base and 6-blade turbine mounted 3-inches from the bottom. The
resulting emulsion was mixed for next 30 minutes. At 30 minutes the
multifunctional azo initiator was added and started to purge the
reaction with nitrogen (about 1 L/min). The initiator molecule
(0.40 to 0.012 ) was charged as a solution in DMF, or as powder
into the emulsion or it was semi batched over 2-4 hrs.
Polymerization was started at 40.degree. C. and during the reaction
the temperature was increase to 70.degree. C. At the end of the
polymerization the reaction held at 70.degree. C. for one hour and
cooled to room temperature. A polymer solution was made up by
mixing 2.0 g of water-in-oil emulsion and 198 g water with 0.12 g
of nonionic surfactant alcohol ethoxylate (Clariant Basel,
Switzerland), in a 300 ml tall beaker for 30 minutes with vigorous
mixing. An RSV of 19.2 dl/g (1M NaNO.sub.3, 450 ppm, 30.degree. C.)
was measured for the polymer.
5B) Inverse emulsion polymerization of
Acrylamide/Dimethylaminoethyl acrylate methyl chloride quaternary
salt copolymers using multifunctional initiator and other
structuring agents such as MBA or HEMA
[0076] An aqueous monomer phase was made up dissolving 9.82 g
Adipic acid (Sigma-Aldrich, St. Louis, Mo.) and 34.78 g DI water in
227.74 g of 49.5% aqueous solution of Acrylamide (Nalco Company,
Naperville, Ill.). The components were stirred until a homogenous
solution was formed. To this solution added 0.1 g of EDTA followed
by 384.084 g Dimethylaminoethyl acrylate methylchloride (DMAEA-MCQ,
SNF Riceboro, Ga.), followed by 2-5 g of 2-hydroxyethyl acrylate
and/or 0.1 to 10 g of 1% methylene bisacrylamide and mixed well. An
oil phase was prepared from 274.96 g of hydrocarbon solvent (Exxon
Chemical Company, Houston, Tex.), 14.1 g Arlacel 80AC (Uniqema, New
Castle, Del.) and 16.3 g Tween 85 (Uniqema, New Castle, Del.) at
room temperature. Oil phase was added to a 1500 mL reactor set at
40.degree. C. When oil phase addition was complete rate of mixing
was increased from 500 rpm to 1000 rpm and added the monomer phase
slowly into the oil phase. The mixing was accomplished by a 10 mm
rod with a Teflon paddle at the base and 6-blade turbine mounted
3-inches from the bottom. The resulting emulsion was mixed for next
30 minutes. At 30 minutes the multifunctional azo initiator was
added and started to purge the reaction with nitrogen (about 1
L/min). The initiator molecule (0.40 to 0.012 g) was charged as a
solution in DMF, or as powder into the emulsion or it was semi
batched over 2-4 hrs. Polymerization was started at 40.degree. C.
and during the reaction the temperature was increase to 70.degree.
C. At the end of the polymerization the reaction held at 70.degree.
C. for one hour and cooled to room temperature. A polymer solution
was made up by mixing 2.0 g of water-in-oil emulsion and 198 g
water with 0.12 g of nonionic surfactant alcohol ethoxylate
(Clariant Basel, Switzerland), in a 300 ml tall beaker for 30
minutes with vigorous mixing. An RSV of 10.8 dl/g (1M NaNO.sub.3,
450 ppm, 30.degree. C.) was measured for the polymer. Reactions
were also conducted with methylene bisacrylamide (but at much lower
concentrations compared to 2-hydroxycthyl acrylate) to obtain
similar results.
5C) Inverse emulsion polymerization of
Acrylamidc/Dimethylaminoethyl acrylate methyl chloride quaternary
salt copolymers using 4 functional peroxide initiator
[0077] An aqueous monomer phase was made up dissolving 9.82 g
Adipic acid (Sigma-Aldrich, St. Louis, Mo.) and 34.78 g DI water in
227.74 g of 49.5% aqueous solution of Acrylamide (Nalco Company,
Naperville, Ill.). The components were stirred until a homogenous
solution was formed. To this solution added 0.1 g of EDTA followed
by 384.084 Dimethylaminoethyl acrylate methylchloride (DMAEA-MCQ,
SNF Riceboro, Ga.) and mixed well. An oil phase was prepared from
274.96 g of hydrocarbon solvent (Exxon Chemical Company, Houston,
Tex.), 14.1 g Arlacel 80AC (Uniqema, New Castle, Del.) and 16.3 g
Tween 85 (Uniqema, New Castle, Del.) at room temperature. Oil phase
was added to a 1500 mL reactor set at 50.degree. C. When oil phase
addition was complete rate of mixing was increased from 500 rpm to
1000 rpm and added the monomer phase slowly into the oil phase. The
mixing was accomplished by a 10 mm rod with a Teflon paddle at the
base and 6-blade turbine mounted 3-inches from the bottom. The
resulting emulsion was mixed for next 30 minutes. At 30 minutes
depending on the reaction 0.25 to 1.0 g of 4-functional peroxide
(Arkema's Luperox.RTM. Jweb50) initiator was added and started to
purge the reaction with nitrogen (about 1 L/min). Polymerization
was started at 50.degree. C. and during the reaction the
temperature was increase to 70.degree. C. At the end of the
polymerization the reaction held at 70.degree. C. for one hour and
cooled to room temperature. A polymer solution was made up by
mixing 2.0 g of water-in-oil emulsion and 198 g water with 0.12 g
of nonionic surfactant alcohol ethoxylate (Clariant Basel,
Switzerland), in a 300 ml tall beaker for 30 minutes with vigorous
mixing. An RSV of 15.4 dl/g (1M NaNO.sub.3, 450 ppm, 30.degree. C.)
was measured for the polymer.
Flocculation Performance of Copolymers
[0078] The effectiveness of various star polymers was demonstrated
by a free drainage test, which compared their flocculation and
dewatering performance. The polymer is activated by inverting it at
a concentration of typically 2200 mg/L on an actives basis in DI
water under vigorous stirring using a cage stirrer at 800 rpm for
30 minutes. 200 mL of sludge sample is conditioned with a specified
volume of the polymer solution in a 500 mL cylinder by manually
inverting the cylinder a specified number of times, usually 5, 10
or 20 depending on the amount of shear to be simulated. Since the
polymer dose is varied, a specified volume of dilution water is
added to the sludge prior to conditioning so that the total volume
of water added via the polymer and the dilution water is constant,
usually 25 mL. The conditioned sludge is filtered under gravity
through a constant area of a belt press fabric, usually either 41
cm.sup.2 or 85 cm.sup.2. The filtrate mass is measured as a
function of time via an electronic balance. The mass of the
filtrate at a specified time is plotted against polymer dosage for
various polymers.
[0079] FIG. 4 illustrates the performance advantages of these new
molecules at 30 seconds of drainage in the dewatering of sludge
from a chemical industry. An ideal polymer would show high drainage
(high effectiveness) preferably occurring at low polymer dosage
(high efficiency). A prior art linear polymer shows very low
filtrate mass over a wide range of polymer dosage i.e. poor
effectiveness. Increasing the polymer dosage further, reduces the
drainage because of the so called "overdose effect". In the
"overdose effect" increasing the dosage of polymer beyond its
optimum value causes it to remain on the exterior of the floc
aggregates which then adhere to the filtration fabric and blind it.
Secondly, the excess polymer also increases the viscosity of the
filtrate, both of which contribute to a reduced drainage rate.
[0080] A prior art cross-linked polymer is effective (it drains
higher amounts of water) but it is inefficient because it yields
these results only at high dosages. The cross-linked polymer also
has a relatively level slope in the region of optimum dosage,
indicating an absence of the overdose effect. 6-arm, 5-arm, 4-arm,
and 3-arm polymers all show better effectiveness than the linear
polymer and are more efficient than the cross-linked polymer
because they function at lower dosages. The 3-arm polymer in
particular matches the best effectiveness of the cross linked
polymer, but at dosages less than that of the cross-linked polymer,
indicating its superior efficiency.
[0081] FIG. 5 illustrates the effectiveness and efficiency of star
polymers relative to cross-linked and linear polymers at 10 seconds
of drainage when applied to the dewatering of sludge from a
refinery. It shows that 3-arm, 4-arm polymers are nearly as
effective at achieving high drainage and much more efficient in
polymer dosage compared to the cross-linked polymer. The 3-arm,
4-arm and 5-arm star polymers are much more effective at achieving
high drainage than the linear polymer. In at least one embodiment,
the star polymer is itself treated by cross linking agents to form
an even more structured star polymer having at least one cross
linkage between at least two star polymer arms in addition to the
multifunctional core. These even more structured star polymers have
enhanced dewatering properties.
[0082] FIG. 6 shows performance advantage of the polymers made
using these novel initiators (labeled "Polyfunctional") compared
with prior art cross-linked, linear polymers, and peroxide
initiator based polymers. The results show that the 3-arm, 4-arm
star polymers made from the novel initiators perform more
effectively than the prior art linear polymer and the
multifunctional peroxide initiator based polymer, and are more
efficient than the cross-linked polymer, with only marginal
decrease in effectiveness.
[0083] The superior performance of star polymers arises from their
unique solution viscosity properties. The viscosity of a star
polymer is high at a high solution concentration e.g. 0.5% wt
product in water, but decreases sharply at lower concentration e.g.
below 0.3% wt product. In contrast, the viscosity of a linear
polymer is not as high as that of the star polymer at high
concentration and decreases gradually with decrease in solution
concentration of the polymer. A cross-linked polymer shows a very
low viscosity that is nearly independent of concentration in the
concentration range of 0.5% wt to 0.05% wt. In the initial stage of
flocculation, the high viscosity star polymer solution forms large
floc aggregates of the primary particles in the sludge suspension.
Upon further mixing of the star polymer solution and the sludge
suspension, the floc aggregates become more compact and dense
compared to the case of a linear polymer solution, since its
decreasing solution viscosity allows faster rearrangement of
polymer molecules within the floe aggregate. This compact floe
architecture releases more free water, resulting in faster
drainage, compared to the floes obtained from conditioning with a
linear polymer. A cross-linked polymer solution will also provide a
compact floc architecture giving high drainage rates, but due to
its low viscosity, will form small floes each containing a smaller
number of primary particles. Therefore, to flocculate all particles
of a suspension, a larger polymer dosage of the cross-linked
polymer is required, making it less efficient. A star polymer
combines the low dosage benefit of the linear polymer and the high
drainage benefit of the cross-linked polymer, making it a superior
product.
[0084] In at least one embodiment the performance of one or more
polymers can be enhanced, by dosing the same quantity of polymer as
a mixture of solutions with different polymer concentrations. The
different polymer concentrations have more than one viscosity.
Dosing the polymer in solutions of two different viscosities
increases drainage effectiveness compared to dosing it as a
solution of one concentration (and hence viscosity). The high
viscosity solution forms large and compact floe aggregates as
described above. At polymer dosages above the optimum value, the
"overdose effect" described previously is mitigated by the low
viscosity solution, because it is easily incorporated into the floe
aggregate, producing dense, non-sticky floes.
[0085] In at least one embodiment represented by FIG. 7, the
performance of a star polymer is improved by this dual dosing
process. The dual dosing process is even more effective with star
polymers than with linear polymers because the difference in
viscosity with concentration is more pronounced in star
polymers.
[0086] FIG. 7 specifically illustrates the results of an experiment
demonstrating the dual dosing process with a 4-arm star polymer on
a sludge sample from a refinery. In this experiment, a fixed
quantity of polymer was fed as an equal combination of 0.5% wt
solution and a 0.25% wt solution on a product basis. Both polymer
solutions were injected into the sludge sample at the same time and
mixed with the sludge for the same number of inversions as the base
case of 0.5% wt solution alone. Thus, there was no confounding
effect of different energies of mixing or the improved drainage
that is known to occur from a sequential feed of polymer. With
increasing dosage, the proportion of the 0.25% wt solution to the
0.5% wt solution increased, since the need was to avoid more of the
high viscosity solution (i.e. 0.5 % wt solution) at excessive
dosages. Replicates were run to check reproducibility.
[0087] As seen from FIG. 7, there is no decrease in drainage rate
at excessive dosages when the dual concentration solutions are
used, in contrast to the decrease in drainage when the high polymer
concentration solution is used. This is because any excess polymer
is present as a low viscosity solution (in the dilute 0.25% wt
form), which is much easier to incorporate into the interior of the
floc, making it denser and less sticky on the exterior surface.
Thus, there is no fouling of the filtration fabric at excessive
dosage. This feeding scheme has the advantage that the operating
dosage window of the polymer is now larger and variations in the
solids content of the influent sludge can be more easily
handled.
[0088] Referring now to FIG. 8 there is shown a prior art feeder
system commonly used in the industry for activating polymer into
solution. The prior art feeder adds neat polymer product (polymer
as stored) and water to a mixing chamber to a desired concentration
and then outputs the polymer solution at that concentration
(Polymer Solution Output). The prior art feeder includes a primary
water input (Water 1) and a secondary water input (Water 2), which
is an option for further dilution of the polymer solution, as well
as a Polymer Solution Output.
[0089] FIG. 9 illustrates a novel cost effective modification to
the feeder system, which allows for use of the dual dosing process
with existing feeder systems. In addition to a first water input
(901) controlled by a first valve (931) in fluidic communication
with a mixing chamber (999) this feeder system has a second input
pipe (912) extending the supply of secondary water input (902) to a
second polymer solution output (922). This second input pipe (912)
allows the contents of the first polymer solution output (921) to
be further diluted into the second polymer solution output (922).
The second input pipe (912) can be controlled by second valve
(932).
[0090] The flow of water into the second polymer solution output
(922) can be controlled by a third valve (903) into a mixing pipe
(955), while the fraction of first polymer solution output (921) to
be diluted can be controlled by a fourth valve (904) into a fourth
pipe (914) which also feeds into the second polymer solution output
(922). Using this method and apparatus, a specified fraction of the
first polymer solution output (921) can be diluted to a known
concentration and fed into the application as the second polymer
solution output (922), which is of lower viscosity. The first
polymer solution output (921) and the second polymer solution
output (922) can either be combined into a single stream via a
header just prior to the injection point into the suspension to be
flocculated, or can be fed as two different streams. By regulating
the third and fourth valves (903 and 904), any combination of high
viscosity and low viscosity polymer solutions can be injected into
the application for optimum drainage performance. In at least one
embodiment, the apparatus comprises a polymer input pipe (950)
[0091] While this invention may be embodied in many different
forms, there are shown in the drawings and described in detail
herein specific preferred embodiments of the invention. The present
disclosure is an exemplification of the principles of the invention
and is not intended to limit the invention to the particular
embodiments illustrated. Furthermore, the invention encompasses any
and all possible combinations of some or all of the various
embodiments described herein. Any and all patents, patent
applications, scientific papers, and other references cited in this
application are hereby incorporated by reference in their
entirety.
[0092] The above disclosure is intended to be illustrative and not
exhaustive. This description will suggest many variations and
alternatives to one of ordinary skill in this art. All these
alternatives and variations are intended to be included within the
scope of the claims where the term "comprising" means "including,
but not limited to". Those familiar with the art may recognize
other equivalents to the specific embodiments described herein
which equivalents are also intended to be encompassed by the
claims.
[0093] This completes the description of the preferred and
alternate embodiments of the invention. Those skilled in the art
may recognize other equivalents to the specific embodiment
described herein which equivalents are intended to be encompassed
by the claims attached hereto.
* * * * *