U.S. patent application number 11/766730 was filed with the patent office on 2007-11-08 for synthesis of poly (ethylene amine) on an oxide support.
Invention is credited to Eric L. Burch, Thomas Schuman, James O. Stoffer.
Application Number | 20070259775 11/766730 |
Document ID | / |
Family ID | 34465636 |
Filed Date | 2007-11-08 |
United States Patent
Application |
20070259775 |
Kind Code |
A1 |
Burch; Eric L. ; et
al. |
November 8, 2007 |
SYNTHESIS OF POLY (ETHYLENE AMINE) ON AN OXIDE SUPPORT
Abstract
Methods of polymerizing polyethylene-based polymers on a
support, and supports coated with polyethylene-based polymers. The
coated supports may be used to improve the ink fixation properties
of an ink-jet printing medium. The coated supports may also be
useful for highly tailored chromatographic separations.
Inventors: |
Burch; Eric L.; (San Diego,
CA) ; Stoffer; James O.; (Rolla, MO) ;
Schuman; Thomas; (Rolla, MO) |
Correspondence
Address: |
HEWLETT PACKARD COMPANY
P O BOX 272400, 3404 E. HARMONY ROAD
INTELLECTUAL PROPERTY ADMINISTRATION
FORT COLLINS
CO
80527-2400
US
|
Family ID: |
34465636 |
Appl. No.: |
11/766730 |
Filed: |
June 21, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10703650 |
Nov 7, 2003 |
7250388 |
|
|
11766730 |
Jun 21, 2007 |
|
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|
Current U.S.
Class: |
502/159 |
Current CPC
Class: |
B01J 20/286 20130101;
B01J 20/285 20130101; B01J 20/328 20130101 |
Class at
Publication: |
502/159 |
International
Class: |
B01J 35/02 20060101
B01J035/02 |
Claims
1-6. (canceled)
7. A catalyst comprising: a surface comprising a polymer formed
from a plurality of monomers comprising one or more monomer types,
at least one of the one or more monomer types having an amine
functional group; and an active molecule immobilized on the
surface, wherein the active molecule is selected to promote a
chemical reaction in a reagent.
8. The catalyst of claim 0, wherein the active molecule is an
enzyme.
9. The catalyst of claim 0, wherein the active molecule is a
metal.
10. The catalyst of claim 0, wherein one of the one or more monomer
types is ethylene imine.
11. The catalyst of claim 0, wherein one of the one or more monomer
typos is ethylene oxide.
12. The catalyst of claim 0, wherein the catalyst acts as a
selective catalyst.
13. The medium of claim 0, wherein the polymer has a porosity, pore
dimension, hydrophobicity pH, or surface chirality selected to
promote separation of components of the reagent.
Description
FIELD OF THE INVENTION
[0001] This invention pertains to absorptive coatings for ink-jet
printing and ion-exchange, and, more specifically, coatings that
are polymerized from and covalently linked to a support.
BACKGROUND OF THE INVENTION
[0002] The interaction of ink printed by thermal ink-jet printing
and a printed substrate preferably exhibits both short term and
long term stability. Ink-jet receiving layers, e.g., plain paper or
a coating on coated media, need to absorb the printed ink-vehicle
to control the spread of color drops and prevent cooling or
coalescence of the ink. In addition, the surface of the printed
media need to prevent excess horizontal migration of an ink spot
over the surface. Long term durability includes smearfastness,
smudgefastness, waterfastness, and lightfastness. Smearfastness and
a smudgefastness are measures of a printed ink's resistance to
physico-chemical and physical abrasion, respectively. Waterfastness
is a measure of the insolubility of the ink after printing. For
example, the printed media should prevent migration of the ink
after drying of an image upon exposure to moisture, for example,
perspiration, rain or spilled drops of water. Lightfastness is a
measure of the capacity of the printed media to retain images
thereon in a stable fashion without substantial fading, blurring,
distortion, and the like over time in the presence of natural or
made-made light.
SUMMARY OF THE INVENTION
[0003] In one aspect, the invention comprises a medium for
chromatographic separations, comprising a surface comprising a
polymer, and an active molecule immobilized on the surface. The
polymer is formed from a plurality of monomers comprising one or
more monomer types (e.g., ethylene imine or ethylene oxide). At
least one of these monomer types has an amine functional group. The
active molecule is selected to separate reagent materials by
chemical structure. In still another aspect, the invention
comprises a catalyst, comprising a surface comprising a polymer,
and an active molecule immobilized on the surface. At least one of
these monomer types has an amine functional group.
BRIEF DESCRIPTION OF THE DRAWING
[0004] The invention is described with reference to the several
figures of the drawing, in which,
[0005] FIG. 1 is a diagram of an ink-jet print medium according to
one embodiment of the invention;
[0006] FIG. 2 is a diagram of an ink-jet print medium according to
another embodiment of the invention; and
[0007] FIG. 3 is a diagram of a packed column that may be used for
chromatographic separations according to still another embodiment
of the invention.
DEFINITIONS
[0008] "Biomolecules": The term "biomolecules", as used herein,
refers to molecules (e.g., proteins, amino acids, peptides,
polynucleotides, nucleotides, carbohydrates, sugars, lipids,
nucleoproteins, glycoproteins, lipoproteins, steroids, etc.)
whether naturally-occurring or artificially created (e.g., by
synthetic or recombinant methods) that are commonly found in cells
and tissues. Specific classes of biomolecules include, but are not
limited to, enzymes, receptors, neurotransmitters, hormones,
cytokines, cell response modifiers such as growth factors and
chemotactic factors, antibodies, vaccines, haptens, toxins,
interferons, ribozymes, anti-sense agents, plasmids, DNA, and
RNA.
[0009] "Polynucleotide," "nucleic acid," or "oligonucleotide": The
terms "polynucleotide," "nucleic acid," or "oligonucleotide" refer
to a polymer of nucleotides. The terms "polynucleotide", "nucleic
acid", and "oligonucleotide", may be used interchangeably.
Typically, a polynucleotide comprises at least three nucleotides.
DNAs and RNAs are polynucleotides. The polymer may include natural
nucleosides (i.e., adenosine, thymidine, guanosine, cytidine,
uridine, deoxyadenosine, deoxythymidine, deoxyguanosine, and
deoxycytidine), nucleoside analogs (e.g., 2-aminoadenosine,
2-thiothymidine, inosine, pyrrolo-pyrimidine, 3-methyl adenosine,
C5-propynylcytidine, C5-propynyluridine, C5-bromouridine,
C5-fluorouridine, C5-jodouridine, C5-methylcytidine,
7-deazaadenosine, 7-deazaguanosine, 8-oxoadenosine, 8-oxoguanosine,
O(6)-methylguanine, and 2-thiocytidine), chemically modified bases,
biologically modified bases (e.g., methylated bases), intercalated
bases, modified sugars (e.g., 2'-fluororibose, ribose,
2'-deoxyribose, arabinose, and hexose), or modified phosphate
groups (e.g., phosphorothioates and 5'-N-phosphoramidite
linkages).
[0010] "Polypeptide", "peptide", or "protein": According to the
present invention, a "polypeptide", "peptide", or "protein"
comprises a string of at least three amino acids linked together by
peptide bonds. The terms "polypeptide", "peptide", and "protein",
may be used interchangeably. Peptide may refer to an individual
peptide or a collection of peptides. Inventive peptides preferably
contain only natural amino acids, although non-natural amino acids
(i.e., compounds that do not occur in nature but that can be
incorporated into a polypeptide chain; see, for example,
http://www.cco.caltech.edu/.about.dadgrp/Unnatstruct.gif, which
displays structures of non-natural amino acids that have been
successfully incorporated into functional ion channels) and/or
amino acid analogs as are known in the art may alternatively be
employed. Also, one or more of the amino acids in an inventive
peptide may be modified, for example, by the addition of a chemical
entity such as a carbohydrate group, a phosphate group, a farnesyl
group, an isofarnesyl group, a fatty acid group, a linker for
conjugation, functionalization, or other modification, etc. In a
preferred embodiment, the modifications of the peptide lead to a
more stable peptide (e.g., greater half-life in vivo). These
modifications may include cyclization of the peptide, the
incorporation of D-amino acids, etc. None of the modifications
should substantially interfere with the desired biological activity
of the peptide.
[0011] "Polysaccharide", "carbohydrate" or "oligosaccharide": The
terms "polysaccharide", "carbohydrate", or "oligosaccharide" refer
to a polymer of sugars. The terms "polysaccharide", "carbohydrate",
and "oligosaccharide", may be used interchangeably. Typically, a
polysaccharide comprises at least three sugars. The polymer may
include natural sugars (e.g., glucose, fructose, galactose,
mannose, arabinose, ribose, and xylose) and/or modified sugars
(e.g., 2'-fluororibose, 2'-deoxyribose, and hexose).
[0012] "Absorptivity": The term "absorptivity", as used herein,
refers to the ability of an ink-jet print medium to absorb or bind
dye or pigment from an ink (which usually comprises dye and/or
pigment in a carrier fluid). The term "absorptivity" may also be
used to describe the ability of a column to absorb or bind one or
more components of a reagent fluid. "Binding" includes covalent
bonding, electrostatic interaction, van der Waals attractions,
dipole-dipole attractions, pi-bonding, physical entanglement, and
all other forms of chemical or physical attachment.
DETAILED DESCRIPTION
[0013] The invention provides methods of modifying a surface to
produce a high isoelectric point support with a high ion-exchange
capability and particle dispersion stability. In general, a
polyethylene-based coating such as poly(ethylene imine) (PEI) is
polymerized from the surface of a support such as silica or
alumina. The polymer is linked to the support through covalent
bonds between a functional group of the polymer and the negatively
charged (e.g., --SiO.sup.- or --Al.sub.2O.sub.2.sup.-) surface of
the support. This linkage reduces or prevents the desorption and
surface rearrangement problems that can occur when adsorbed
polyimine species are exposed to extreme pH levels. Polymerization
from the surface of the support allows control of the physical and
chemical properties of the composite through independent variation
of the support particle size, polymer layer thickness, and polymer
composition (through copolymerization). The support may be
monolithic, for example, a particle, or a coating on a substrate,
for example, a coated paper. In one embodiment, the support is
deposited on the paper or other substrate as a sol. FIG. 1 shows
coated particulate supports deposited onto a paper substrate
according to the invention, while FIG. 2 shows a paper substrate
coated with a layer of silica and a polymer coating.
[0014] The polymeric material may be polymerized from the support
before or after attachment to the substrate. Polymerization before
attachment facilitates the use of wet chemistry during
polymerization, which is typically more versatile, while
polymerization after attachment may be more conveniently achieved,
for example, by use of solid monomers dry-cured with heat,
radiation, or the application of a catalyst. Polymerization after
attachment also avoids difficulties with the attachment of the
support to the substrate due to materials incompatibilities (e.g.,
viscosity changes), and may facilitate a greater degree of
interpenetration between the polymer and the support. In addition,
concentration changes in the monomer layer may be used to form a
polymer having gradient properties, such as a higher molecular
weight near the surface and a lower molecular weight in the near
the support.
[0015] In a preferred embodiment, the polymer is prepared by
ring-opening polymerization, although a free radical polymerization
may also be used to prepare the polymers of the invention. Both
ends of the polymer and the secondary amines along the chain can
react with the ethylene imine monomer. As a result, the final
polymer products will be a highly interwoven polymer such as a
dendritic, branched, or hyper-branched polymer. The coating
provides a porous, three-dimensional interwoven surface reminiscent
of a sponge.
[0016] In one embodiment, the surface of the support is modified by
nucleophilic addition. For example, amines, thiols, metals, metal
oxides, and alkoxides may be covalently attached to the surface of
the support before polymerization. These polymerization initiators
may be attached to the support surface prior to polymerization, for
example via organosilanes or amino acids bonded to the support
surface. In general, it is preferred that such a separate initiator
be used if polymerization directly from the support would require
conditions tending to degrade or dissolve the substrate. For
example, in ethyleneimine reactions, a surface alkoxide initiator
is not preferred with an alumina substrate because the strongly
basic condition tends to dissolve the substrate, causing
polymerization to occur from free-floating dissolved alkoxides,
rather than solely from the subtrate surface. For silicon-based
substrates, chemical attachment is preferably made by using a
halo-silica or hydroxy silica compound that condenses with the
silicon surface groups. Functional groups attached to the
organosilicon are then used as polymerization initiators.
[0017] The thickness of polymer deposited on the support surface
may be controlled, for example by the use of a starved-feed
polymerization. Those of ordinary skill in the art will understand
how to calculate the approximate number of surface sites on the
support in order to determine molecular weight and thickness. For
example, silane has a footprint of approximately 50 square
angstroms, while a simple poly(ethylene imine) chain has a
footprint of approximately 100 square angstroms. Thus, it is
expected that about half of the initiator sites will be occupied.
This information, along with the size of the monomer species, can
be used to determine how much monomer should be added in order to
obtain a given coating thickness.
[0018] Polymerization may be carried out in either a batch or
continuous process, or in a semicontinuous process in which a
quantity of reaction mixture is transported from tank to tank. In
one embodiment of the invention, polymerization is carried out in a
continuous or semicontinuous process by passing supports
(optionally modified as discussed above) through one or more tanks
or pipelines receiving the ethylene imine monomer feed. This
monomer boils at a temperature of about 5.degree. C., so the
reaction is preferably carried out at a lower temperature, and/or
under sufficient pressure to condense the monomer. The relatively
low boiling point of the monomer may be advantageous for
processing, since no centrifugation is required to remove excess
monomer after polymerization--the supports can simply be exposed to
ambient temperature and pressure in order to vaporize and recover
any unreacted monomer.
[0019] In a continuous or semicontinuous starved-feed process,
residence time is typically not exactly equal to reaction time,
because the monomer is not always available to each particle in the
tank. The more evenly distributed the monomer is through the
reaction mixture, the more evenly distributed the molecular weight
of the coatings will be. Thus, those skilled in the art will
recognize that the fluid dynamics of the monomer-support mixture
should be well understood and controlled in order to achieve the
most reproducible results. However, when polymer thickness and
molecular weight are not of major concern, even relatively crude
control of the support-monomer interaction can produce adequately
coated supports for use in the invention.
[0020] A wide variety of materials may be attached to the polymer
surface after polymerization. One skilled in the art will be
familiar with the many functional groups that may be attached to a
surface by nucleophilic addition. Exemplary reactions are described
in Odian, Principles of Polymerization, Wiley-Interscience, 1991,
which is incorporated herein by reference. Alternative support
surface groups, such as boehmite, zirconate or titanate, may also
be used to exploit the techniques of the invention. One skilled in
the art will recognize that the PEI can be covalently attached via
polymerization to almost any nucleophilic surface.
[0021] One skilled in the art will recognize that the properties of
the polymer-coated surface depend partially on the properties of
the support. For example, an alumina or boehmite surface exhibits
certain ion exchange and dye fixation properties. The techniques of
the invention allow one skilled in the art to tailor the surface
charge and dye fixation properties of the surface. The PEI coatings
of the invention convert the silica surface from a low isoelectric
point, acidic surface to a higher iso-electric point, basic surface
allowing adsorption of acidic species. The properties of an
unmodified PEI surface may depend on the pH of an ink or other
solution to which they are subsequently exposed. Even more basic
surface properties may be achieved by surface modification of the
PEI coating. For example, the PEI coatings of the invention allow
strongly basic groups such as quaternary ammonium alkyl compounds
to be tethered an alumina surface by addition of methyl compounds
such as methyl bromide, methyl iodide, or similar compounds that
react with the amino group of the PEI by ion exchange to yield
quaternary ammonium groups. Those of ordinary skill in the art will
recognize that the counterion selected will have a significant
effect on ink absorption. Iodine is better for fast, quantitative
exchange than bromine anion for exchange with a smaller chlorine
anion, and better to exchange with multivalent ions such as
phosphate, organophosphate, or sulfate. This ion exchange chemistry
is described in common ion exchange literature, for example Nachod,
"Ion exchange Technology" (Academic press, NY, 1956), and Kunin,
"Elements of ion exchange" (Reinhold, N.Y., 1960), which are
incorporated by reference herein. In some cases, it may be
advantageous to reduce the intensity of ion exchange/adsorption in
ink-jet print media to reduce coalescence of the dyes prior to dye
penetration of the surface. Reducing the rate of adsorption using
alternative anions, such as bromide, sulfate, or chloride, may
reduce adsorption efficiency but allow relatively irreversible
adsorption (fixing) of dyes for image water and humidity bleed
resistance. Addition of these and other functional groups to the
surface can be achieved as part of a continuous reaction
process.
[0022] Poly(ethylene imine) is a common fixing agent for dyes.
Still, one skilled in the art will recognize that it may be
desirable to tether other agents to the coating to enhance its dye
fixing abilities. For example, a cross-linking agent, such as a
diisocyanate, diexpoxide, glyoxal, glutaraldehyde, dicarboxy acid
(in the presence of carbodiimide), di(N-acylimidazoles), or
di(vinylsulfone), may be added to the PEI coating to improve its
physical durability under both wet and dry conditions and to
improve water resistance. Fade protecting molecules such as UV
Absorbers, HALS, or antioxidants may be added to the coating to
improve lightfastness. These groups may be covalently attached to
the polymer or may be retained on the polymer through electrostatic
interactions with the amine groups on the polymer. Interparticle
spacing of the supports through use of the polymer layer thickness
may be utilized to filter unwanted light, to reduce yellow hues
from the paper or ultraviolet from ambient sources.
[0023] The techniques of the invention promote smudgefastness of a
printed ink by promoting good wetting and electrostatic
interactions between the dye and the coating substrate. The coating
may also enhance lightfastness of dyes printed on alumina surfaces
by fixing the dye molecules, providing fixed dye structures as
nucleation sites for further aggregation.
[0024] In an alternative embodiment, the techniques of the
invention may be used to modify the chromatographic properties of
ion-exchange resins. While materials such as silica and alumina
already possess ion-exchange properties and are commonly used to
perform chromatographic separations, the techniques of the
invention may be used to enhance the selectivity of these materials
through variation of porosity, pore dimension, hydrophobicity, pH,
or surface chirality. For example, biomolecules such as antibodies,
polynucleotides and enzymes may be tethered onto PEI-coated silica
particles and packed into a column, as shown in FIG. 3. Reaction
catalysts may be attached for fixed bed or dispersible reaction
catalysis, such as surface metal oxides. Alternatively, particles
may be fabricated from a molecularly nucleated PEI without the need
for a solid support.
[0025] The column, instead of merely separating materials based on
non-specific interactions such as hydrogen bonding, will separate
materials based on their chemical structure. A column loaded with
antibody-coated particles will separate a specific antigen from a
solution. Likewise, polynucleotide coated particles will organize
the DNA or RNA in a solution in order of its degree of
hybridization with the immobilized polynucleotide. The DNA or RNA
sequence having the worst match with the immobilized polynucleotide
will emerge from the column first, while nucleotide sequences that
are the best match to the immobilized polynucleotide will emerge
last. Indeed, highly polar solvents may be required to separate
these DNA or RNA sequences from the polynucleotide immobilized on
the column. If enzymes are immobilized on the column, materials
passing through the column will undergo the reactions catalyzed by
those enzymes, and the reaction products may be collected at the
end of the column.
[0026] Alternatively, a silica particle may be modified to separate
materials flowing through the column by mass or density. For
example, hydrocarbon chains may be attached directly to the
particle, a PEI coated particle, or a PEI particle through
nucleophilic addition. As materials proceed through the column,
they must negotiate past the hydrocarbon chains to adsorb onto the
silica particle. For example, in a mixture of proteins and small
molecules, the proteins will be unable to interact with the silica
particles due to the hydrocarbon buffer, while the small molecules
will easily penetrate the buffer layer and adsorb onto the silica
particles.
[0027] Other embodiments of the invention will be apparent to those
skilled in the art from a consideration of the specification or
practice of the invention disclosed herein. It is intended that the
specification and examples be considered as exemplary only, with
the true scope and spirit of the invention being indicated by the
following claims.
* * * * *
References