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US3928255A Expired / Lapsed US ⏱️ 0.0 years remaining

Chemically joined, phase separated self-cured hydrophilic thermoplastic graft copolymers and their preparation

Assignee: Unilever Bestfoods North America
•
Filing: 1974-01-11
•
Granted: 1975-12-23
•
Expires: 1994-01-11
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Abstract

Abstract Disclosed are chemically joined, phase separated self-cured hydrophilic thermoplastic graft copolymers which are copolymers of at least one hydrophilic (water-soluble) ethylenically unsaturated monomer or mixtures thereof (or compounds rendered hydrophilic) and at least one copolymerizable hydrophobic macromolecular monomer having a copolymerizable end group which is copolymerizable with said hydrophilic monomer based on the relative reactivity ratios of the respective copolymerizable moieties, said copolymerizable hydrophobic macromolecular monomer being characterized as having a substantially uniform molecular weight distribution such that its ratio of Mw/Mn is not substantially above about 1.1, and being further characterized as having a molecular weight of at least about 2,000. The copolymers are water-dispersible and water-swellable and are useful in diverse applications such as suspension stabilizers, flocculants, hydrogels (e.g., biomedical hydrogels as contact lenses, artificial organs, etc.), industrial thickeners, ion exchange resins, drilling mud, and they can impart moisture absorption and water permeability (useful in dialysis tubing) as well as antistatic properties to products.

Inventors

  • 👤 Ralph Milkovich
  • 👤 Mutong T Chiang

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-23 11:26
CPC Classifications
C; C08; C08G; C08G63/00; C08G63/02; C08G63/12; C08C; C08C19/00; C08F; C08F2/00; C08F2/04; C08F2/06; C08F2/08; C08F290/00; C08F290/02; C08F290/04; C08F290/044; C08F290/048; C08F8/00; C08F8/02; C08F8/08; C08F8/12; C08F8/14; C08F8/44; C08G18/00; C08G18/06; C08G18/08; C08G18/10; C08G18/28; C08G18/40; C08G18/62; C08G18/6204; C08G81/00; C08G81/02; C08G81/024; C08G81/025; C08J; C08J5/00; C08J5/18; C08F2810/00; C08F2810/30; C08F2810/40; Y; Y10; Y10S; Y10S521/00; Y10S521/905

Claims Analysis

Total Claims: 31
Claim 1
Independent Claim 16 words
AT LAST ONE COPOLYMERIZABLE NORMALLY HYDROPHOBIC MARCORMOLECULAR MONOMER HAVING A SUBSTANTIALLY UNIFORM MOLECULAR WEIGHT DISTRIBUTION, AND
Claim 2
Dependent Claim 16 words
AT LAST ONE COPOLYMERIZABLE NORMALLY HYDROPHOBIC MARCORMOLECULAR MONOMER HAVING A SUBSTANTIALLY UNIFORM MOLECULAR WEIGHT DISTRIBUTION, AND
Claim 3
Dependent Claim 47 words
A HYDROGEL COMPRISING A CHEMICALLY JOINED, PHASE SEPARATED SELF-CURED HYDROPHILIC THERMOPLASTIC GRAFT COPOLYMER IN THE FORM OF A HYDROGEL CONTAINING FROM ABOUT 10 TO ABOUT 95% BY WEIGHT OF AN AQUEOUS LIQUID BASED ON THE WEIGHT OF SAID GRAFT COPOLYMER, WHEREIN SAID GRAFT COPOLYMER IS COPOSED OF
Claim 4
Dependent Claim 47 words
A HYDROGEL COMPRISING A CHEMICALLY JOINED, PHASE SEPARATED SELF-CURED HYDROPHILIC THERMOPLASTIC GRAFT COPOLYMER IN THE FORM OF A HYDROGEL CONTAINING FROM ABOUT 10 TO ABOUT 95% BY WEIGHT OF AN AQUEOUS LIQUID BASED ON THE WEIGHT OF SAID GRAFT COPOLYMER, WHEREIN SAID GRAFT COPOLYMER IS COPOSED OF
Claim 5
Dependent Claim 47 words
A hydrogel comprising a chemically joined, phase separated self-cured hydrophilic thermoplastic graft copolymer in the form of a hydrogel containing from about 10 to about 95% by weight of an aqueous liquid based on the weight of said graft copolymer, wherein said graft copolymer is composed of:
Claim 6
Dependent Claim 47 words
A hydrogel comprising a chemically joined, phase separated self-cured hydrophilic thermoplastic graft copolymer in the form of a hydrogel containing from about 10 to about 95% by weight of an aqueous liquid based on the weight of said graft copolymer, wherein said graft copolymer is composed of:
Claim 7
Dependent Claim 239 words
at least one hydrophilic (water-soluble) copolymerizable comonomer or compound rendered hydrophilic forming the polymeric backbone of said copolymer, said copolymerizable normally hydrophobic macromolecular monomer forming linear polymeric sidechains of said graft copolymer, wherein: a. the polymeric backbones of the graft copolymer are comprised of polymerized units of said copolymerizable comonomers, said copolyMerizable comonomers being at least one ethylenically unsaturated monomer of a hydrophilic or water-soluble compound and mixtures thereof or a compound which can be rendered hydrophilic or water soluble; b. the linear polymeric sidechains of the graft copolymer consist essentially of a polymerized hydrophobic macromolecular monomer, said hydrophobic macromolecular monomer comprising a linear polymer or copolymer having a molecular weight of at least about 2,000 and having a substantially uniform molecular weight distribution, such that its ratio of Mw/Mn is not substantially above about 1.1, said macromolecular monomer being further characterized as having no more than one copolymerizable moiety per linear polymer or copolymer chain, said copolymerization occurring between the copolymerizable end group of said hydrophobic macromolecular monomer and said copolymerizable hydrophilic comonomer; and c. the linear polymeric sidechains of the graft copolymer which are copolymerized into the copolymeric backbone are separated by at least about 20 uninterrupted recurring monomeric units of said hydrophilic polymeric backbone, the distribution of the sidechains along the backbone and the copolymerization being controlled by the reactivity ratios of the copolymerizable end group on said hydrophobic macromolecular monomer and said copolymerizable hydrophilic comonomer.
Claim 8
Dependent Claim 239 words
at least one hydrophilic (water-soluble) copolymerizable comonomer or compound rendered hydrophilic forming the polymeric backbone of said copolymer, said copolymerizable normally hydrophobic macromolecular monomer forming linear polymeric sidechains of said graft copolymer, wherein: a. the polymeric backbones of the graft copolymer are comprised of polymerized units of said copolymerizable comonomers, said copolyMerizable comonomers being at least one ethylenically unsaturated monomer of a hydrophilic or water-soluble compound and mixtures thereof or a compound which can be rendered hydrophilic or water soluble; b. the linear polymeric sidechains of the graft copolymer consist essentially of a polymerized hydrophobic macromolecular monomer, said hydrophobic macromolecular monomer comprising a linear polymer or copolymer having a molecular weight of at least about 2,000 and having a substantially uniform molecular weight distribution, such that its ratio of Mw/Mn is not substantially above about 1.1, said macromolecular monomer being further characterized as having no more than one copolymerizable moiety per linear polymer or copolymer chain, said copolymerization occurring between the copolymerizable end group of said hydrophobic macromolecular monomer and said copolymerizable hydrophilic comonomer; and c. the linear polymeric sidechains of the graft copolymer which are copolymerized into the copolymeric backbone are separated by at least about 20 uninterrupted recurring monomeric units of said hydrophilic polymeric backbone, the distribution of the sidechains along the backbone and the copolymerization being controlled by the reactivity ratios of the copolymerizable end group on said hydrophobic macromolecular monomer and said copolymerizable hydrophilic comonomer.
Claim 9
Dependent Claim 241 words
AT LEAST ONE HYDROPHILIC (WATER-SOLUBLE) COPOLYMERIZABLE COMONOMER OR COMPOUND RENDERED HYDROPHILIC FORMING THE POLYMERIC BACKBONE OF SAID COPOLYMER, SAID COPOLYMERIZABLE NORMALLY HYDROPHOBIC MACROMOLECULAR MONOMER FORMING LINEAR POLYMERIC SIDECHAINS OF SAID GRAFT COPOLYMER, WHEREIN: A. THE POLYMERIC BACKBONES OF THE GRAFT COPOLYMER ARE COMPRISED OF POLYMERIZED UNITS OF SAID COPOLYMERIZABLE COMONOMERS, SAID COPOLYMERIZABLE COMONOMERS BEING AT LEAST ONE ETHYLENICALLY UNSATURATED MONOMER OF A HYDROPHILIC OR WATER-SOLUBLE COMPOUND AND MIXTURES THEREOF OR A COMPOUND WHICH CAN BE RENDERED HYDROPHILIC OR WATER SOLUBLE, B. THE LINEAR POLYMERIC SIDECHAINS OF THE GRAFT COPOLYMER CONSIST ESSENTIALLY OF A POLYMERIZED HYDROPHOBIC MACROABOVE ABOUT 1.1, SAID MACROMOLECULAR MONOMER BEING MONOMER COMPRISING A LINEAR POLYMER OR COPOLYMER HAVING A MOLECULAR WEIGHT OF AT LEAST ABOUT 2,000 AND HAVING A SUBSTANTIALLY UNIFORM MOLECULAR WEIGHT DISTRIBUTION, SUCH THAT ITS RATIO OF MW/MN IS NOT SUBSTANTIALLY ABOVE ABOUT 1.1, SAID MACROMOLECULAR MONOMER BEING FURTHER CHARACTERIZED AS HAVING NO MORE THAN ONE COPOLYMERIZABLE MOIETY PER LINEAR POLYMER OR COPOLYMER CHAIN, SAID COPOLYMERIZATION OCCURRING BETWEEN THE COPOLYMERIZABLE END GROUP OF SAID HYDROPHOBIC MACROMOLECULAR MONOMER AND SAID COPOLYMERIZABLE HYDROPHILIC COMONOMER, AND C. THE LINEAR POLYMERIC SIDECHAINS OF THE GRAFT COPOLYMER WHICH ARE COPOLYMERIZED INTO THE COPOLYMERIC BACKBONE ARE SEPARATED BY AT LEAST ABOUT 20 UNINTERRUPTED RECURRING MONOMERIC UNITS OF SAID HYDROPHILIC POLYERIC BACKBONE, THE DISTRIBUTION OF THE SIDECHAINS ALONG THE BACKBONE AND THE COPOLYMERIZATION BEING CONTROLLED BY THE REACTIVITY RATIOS OF THE COPOLYMERIZABLE END GROUP ON SAID HYDROPHOBIC MACROMOLECULAR MONOMER AND SAID COPOLYMERIZABLE HYDROPHILIC COMONOMER.
Claim 10
Dependent Claim 241 words
AT LEAST ONE HYDROPHILIC (WATER-SOLUBLE) COPOLYMERIZABLE COMONOMER OR COMPOUND RENDERED HYDROPHILIC FORMING THE POLYMERIC BACKBONE OF SAID COPOLYMER, SAID COPOLYMERIZABLE NORMALLY HYDROPHOBIC MACROMOLECULAR MONOMER FORMING LINEAR POLYMERIC SIDECHAINS OF SAID GRAFT COPOLYMER, WHEREIN: A. THE POLYMERIC BACKBONES OF THE GRAFT COPOLYMER ARE COMPRISED OF POLYMERIZED UNITS OF SAID COPOLYMERIZABLE COMONOMERS, SAID COPOLYMERIZABLE COMONOMERS BEING AT LEAST ONE ETHYLENICALLY UNSATURATED MONOMER OF A HYDROPHILIC OR WATER-SOLUBLE COMPOUND AND MIXTURES THEREOF OR A COMPOUND WHICH CAN BE RENDERED HYDROPHILIC OR WATER SOLUBLE, B. THE LINEAR POLYMERIC SIDECHAINS OF THE GRAFT COPOLYMER CONSIST ESSENTIALLY OF A POLYMERIZED HYDROPHOBIC MACROABOVE ABOUT 1.1, SAID MACROMOLECULAR MONOMER BEING MONOMER COMPRISING A LINEAR POLYMER OR COPOLYMER HAVING A MOLECULAR WEIGHT OF AT LEAST ABOUT 2,000 AND HAVING A SUBSTANTIALLY UNIFORM MOLECULAR WEIGHT DISTRIBUTION, SUCH THAT ITS RATIO OF MW/MN IS NOT SUBSTANTIALLY ABOVE ABOUT 1.1, SAID MACROMOLECULAR MONOMER BEING FURTHER CHARACTERIZED AS HAVING NO MORE THAN ONE COPOLYMERIZABLE MOIETY PER LINEAR POLYMER OR COPOLYMER CHAIN, SAID COPOLYMERIZATION OCCURRING BETWEEN THE COPOLYMERIZABLE END GROUP OF SAID HYDROPHOBIC MACROMOLECULAR MONOMER AND SAID COPOLYMERIZABLE HYDROPHILIC COMONOMER, AND C. THE LINEAR POLYMERIC SIDECHAINS OF THE GRAFT COPOLYMER WHICH ARE COPOLYMERIZED INTO THE COPOLYMERIC BACKBONE ARE SEPARATED BY AT LEAST ABOUT 20 UNINTERRUPTED RECURRING MONOMERIC UNITS OF SAID HYDROPHILIC POLYERIC BACKBONE, THE DISTRIBUTION OF THE SIDECHAINS ALONG THE BACKBONE AND THE COPOLYMERIZATION BEING CONTROLLED BY THE REACTIVITY RATIOS OF THE COPOLYMERIZABLE END GROUP ON SAID HYDROPHOBIC MACROMOLECULAR MONOMER AND SAID COPOLYMERIZABLE HYDROPHILIC COMONOMER.
Claim 11
Dependent Claim 239 words
at least one copolymerizable comonomer which is rendered hydrophilic forming the polymeric backbone of said copolymer, said copolymerizable normally hydrophobic macromolecular monomer forming linear polymeric sidechains of said graft copolymer, wherein: a. the polymeric backbone of the graft copolymer is comprised of polymerized units of said copolymerizable comonomers, wherein the copolymerizable comonomers are selected from the group consisting of vinyl esters of monocarboxylic acids which are rendered hydrophilic by hydrolysis of said vinyl esters subsequent to copolymerization, and mixtures thereof; b. the linear polymeric sidechains of the graft copolymer consist essentially of a polymerized hydrophobic macromolecular monomer, said hydrophobic macromolecular monomer comprising a linear polymer or copolymer having a molecular weight of at least about 2,000 and having a substantially uniform molecular weight distribution, such that its ratio of Mw/Mn is not substantially above about 1.1, said macromolecular monomer being further characterized as having no more than one copolymerizable moiety per linear polymer or copolymer chain, said copolymerization occurring between the copolymerizable end group of said hydrophobic macromolecular monomer and said copolymerizable hydrophilic comonomer; and c. the linear polymeric sidechains of the graft copolymer which are copolymerized into the copolymeric backbone are separated by at least about 20 uninterrupted recurring monomeric units of said hydrophilic polymeric backbone, the distribution of the side-chains along the backbone and the copolymerization being controlled by the reactivity ratios of the copolymerizable end group on said hydrophobic macromolecular monomer and said copolymerizable hydrophilic comonomer.
Claim 12
Dependent Claim 239 words
at least one copolymerizable comonomer which is rendered hydrophilic forming the polymeric backbone of said copolymer, said copolymerizable normally hydrophobic macromolecular monomer forming linear polymeric sidechains of said graft copolymer, wherein: a. the polymeric backbone of the graft copolymer is comprised of polymerized units of said copolymerizable comonomers, wherein the copolymerizable comonomers are selected from the group consisting of vinyl esters of monocarboxylic acids which are rendered hydrophilic by hydrolysis of said vinyl esters subsequent to copolymerization, and mixtures thereof; b. the linear polymeric sidechains of the graft copolymer consist essentially of a polymerized hydrophobic macromolecular monomer, said hydrophobic macromolecular monomer comprising a linear polymer or copolymer having a molecular weight of at least about 2,000 and having a substantially uniform molecular weight distribution, such that its ratio of Mw/Mn is not substantially above about 1.1, said macromolecular monomer being further characterized as having no more than one copolymerizable moiety per linear polymer or copolymer chain, said copolymerization occurring between the copolymerizable end group of said hydrophobic macromolecular monomer and said copolymerizable hydrophilic comonomer; and c. the linear polymeric sidechains of the graft copolymer which are copolymerized into the copolymeric backbone are separated by at least about 20 uninterrupted recurring monomeric units of said hydrophilic polymeric backbone, the distribution of the side-chains along the backbone and the copolymerization being controlled by the reactivity ratios of the copolymerizable end group on said hydrophobic macromolecular monomer and said copolymerizable hydrophilic comonomer.
Claim 13
Dependent Claim 292 words
at least one hydrophilic (water-soluble) copolymerizable comonomer or compound rendered hydrophilic forming the polymeric backbone of said copolymer, said copolymerizable normally hydrophobic macromolecular monomer forming linear polymeric sidechains of said graft copolymer, wherein: a. the polymeric backbones of the graft copolymer are comprised of polymerized units of said copolymerizable comonomers, wherein the copolymerizable comonomers are selected from the group consisting of acrylic acid, methacrylic acid, amides of acrylic and methacrylic acids, N-alkyl and N,N-dialkyl amides of acrylic and methacrylic acids, hydroxyalkyl and hydroxyalkoxyalkyl esters of acrylic and methacrylic acids, N-hydroxyalkyl and N,N-bis-hydroxyalkyl amides of acrylic and methacrylic acids, vinyl esters of monocarboxylic acids which are rendered hydrophilic by hydrolysis of said vinyl esters subsequent to copolymerization, N-vinyl pyrrolidone, N-vinyl piperidone, N-acrylylpyrrolidone, N-acrylylpiperidine, N-acrylylmorpholine, quaternary ammonium salts of ethylenically unsaturated compounds, and mixtures thereof; b. the linear polymeric sidechains of the graft copolymer consist essentially of a polymerized hydrophobic macromolecular monomer, said hydrophobic macromolecular monomer comprising a linear polymer or copolymer having a molecular weight of at least about 2,000 and having a substantially uniform molecular weight distribution, such that its ratio of Mw/Mn is not substantially above about 1.1, said macromolecular monomer being further characterized as having no more than one copolymerizable moiety per linear polymer or copolymer chain, said copolymerization occurring between the copolymerizable end group of said hydrophobic macromolecular monomer and said copolymerizable hydrophilic comonomer; and c. the linear polymeric sidechains of the graft copolymer which are copolymerized into the copolymeric backbone are separated by at least about 20 uninterrupted recurring monomeric units of said hydrophilic polymeric backbone, the distribution of the sidechains along the backBone and the copolymerization being controlled by the reactivity ratios of the copolymerizable end group on said hydrophobic macromolecular monomer and said copolymerizable hydrophilic comonomer.
Claim 14
Dependent Claim 292 words
at least one hydrophilic (water-soluble) copolymerizable comonomer or compound rendered hydrophilic forming the polymeric backbone of said copolymer, said copolymerizable normally hydrophobic macromolecular monomer forming linear polymeric sidechains of said graft copolymer, wherein: a. the polymeric backbones of the graft copolymer are comprised of polymerized units of said copolymerizable comonomers, wherein the copolymerizable comonomers are selected from the group consisting of acrylic acid, methacrylic acid, amides of acrylic and methacrylic acids, N-alkyl and N,N-dialkyl amides of acrylic and methacrylic acids, hydroxyalkyl and hydroxyalkoxyalkyl esters of acrylic and methacrylic acids, N-hydroxyalkyl and N,N-bis-hydroxyalkyl amides of acrylic and methacrylic acids, vinyl esters of monocarboxylic acids which are rendered hydrophilic by hydrolysis of said vinyl esters subsequent to copolymerization, N-vinyl pyrrolidone, N-vinyl piperidone, N-acrylylpyrrolidone, N-acrylylpiperidine, N-acrylylmorpholine, quaternary ammonium salts of ethylenically unsaturated compounds, and mixtures thereof; b. the linear polymeric sidechains of the graft copolymer consist essentially of a polymerized hydrophobic macromolecular monomer, said hydrophobic macromolecular monomer comprising a linear polymer or copolymer having a molecular weight of at least about 2,000 and having a substantially uniform molecular weight distribution, such that its ratio of Mw/Mn is not substantially above about 1.1, said macromolecular monomer being further characterized as having no more than one copolymerizable moiety per linear polymer or copolymer chain, said copolymerization occurring between the copolymerizable end group of said hydrophobic macromolecular monomer and said copolymerizable hydrophilic comonomer; and c. the linear polymeric sidechains of the graft copolymer which are copolymerized into the copolymeric backbone are separated by at least about 20 uninterrupted recurring monomeric units of said hydrophilic polymeric backbone, the distribution of the sidechains along the backBone and the copolymerization being controlled by the reactivity ratios of the copolymerizable end group on said hydrophobic macromolecular monomer and said copolymerizable hydrophilic comonomer.
Claim 15
Dependent Claim 47 words
A hydrogel comprising a chemically joined, phase separated self-cured hydrophilic thermoplastic graft copolymer in the form of a hydrogel containing from about 10 to about 95% by weight of an aqueous liquid based on the weight of said graft copolymer, wherein said graft copolymer is composed of:
Claim 16
Dependent Claim 47 words
A hydrogel comprising a chemically joined, phase separated self-cured hydrophilic thermoplastic graft copolymer in the form of a hydrogel containing from about 10 to about 95% by weight of an aqueous liquid based on the weight of said graft copolymer, wherein said graft copolymer is composed of:
Claim 17
Dependent Claim 28 words
The graft copolymer of claim 2, wherein said copolymerizable comonomer which forms said hydrophilic copolymeric backbone is selected from the group consisting of acrylic acid and methacrylic acid.
Claim 18
Dependent Claim 32 words
The graft copolymer of claim 2, wherein said copolymerizable comonomer which forms said hydrophilic copolymeric backbone is selected from the group consisting of hydroxyalkyl and hydroxyalkoxyalkyl esters of acrylic and methacrylic acids.
Claim 19
Dependent Claim 21 words
The graft copolymer of claim 5, wherein said monoester is selected from the group consisting of 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate.
Claim 20
Dependent Claim 30 words
The graft copolymer of claim 2, wherein said copolymerizable comonomer which forms the hydrophilic copolymeric backbone is a water-soluble vinyl monomer having at least one nitrogen atom in the molecule.
Claim 21
Dependent Claim 13 words
The graft copolymer of claim 7, wherein said water-soluble vinyl monomer is N,N-dimethylacrylamide.
Claim 22
Dependent Claim 36 words
The graft copolymer of claim 1, wherein said normally hydrophobic macromolecular monomer which is copolymerized with said copolymerizable comonomer forming the hydrophilic copolymeric backbone is derived from a monofunctional copolymerizable macromolecular monomer represented by the formula:
Claim 23
Dependent Claim 18 words
The graft copolymer of claim 9, wherein said copolymerizable hydrophobic macromolecular monomer is represented by the structural formula:
Claim 24
Dependent Claim 18 words
The graft copolymer of claim 9, wherein said copolymerizable hydrophobic macromolecular monomer is represented by the structural formula:
Claim 25
Dependent Claim 18 words
The graft copolymer of claim 9, wherein said copolymerizable hydrophobic macromolecular monomer is represented by the structural formula:
Claim 26
Dependent Claim 13 words
The graft copolymer of claim 3, wherein said vinyl ester is vinyl acetate.
Claim 27
Dependent Claim 15 words
The graft copolymer of claim 1, wherein the graft copolymer hydrogel is a porous membrane.
Claim 28
Dependent Claim 29 words
The graft copolymer according to claim 2, wherein the copolymerizable comonomers are selected from the group consisting of vinyl pyridine quaternary ammonium salts and dimethylaminoethyl methacrylate quaternary ammonium salts.
Claim 29
Dependent Claim 20 words
The graft copolymer of claim 2, wherein said hydrophilic copolymerizable comonomer is copolymerized in admixture with a hydrophobic copolymerizable comonomer.
Claim 30
Dependent Claim 45 words
The graft copolymer of claim 16, wherein the hydrophobic copolymerizable comonomer is selected from the group consisting of alkyl acrylates and methacrylates, vinyl esters of monocarboxylic acids, vinyl aromatic compounds including styrene and alpha-methylstyrene, vinyl chloride, vinylidene chloride, acrylonitrile, methacrylonitrile, vinylidene cyanide and maleic anhydride.
Claim 31
Dependent Claim 20 words
The graft copolymer of claim 16, wherein said hydrophilic copolymerizable comonomer is N,N-dimethylacrylamide and said hydrophobic copolymerizable comonomer is butylacrylate.

References Cited (Backward Citations)

US3235626A Cited
US3627837A Cited
US3716506A Cited
US3832423A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1978-12-22 1979-06-23 1979-12-23 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1982-12-22 1983-06-23 1983-12-23 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1986-12-22 1987-06-23 1987-12-23 $7700.00 Window Closed / Lapsed

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