# US 10,501,625 B2 · Methods of making acrylamide-acrylic acid copolymers > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,501,625 B2 - Document ID: US10501625B2 - Status: Granted - Kind: B2 - Application number: 15/190,364 - Filed: 2016-06-23 - Published: 2016-12-29 - Granted: 2019-12-10 - Earliest claimed: 2015-06-29 - Assignees: Ecolab USA Inc. - Applicants: Ecolab USA Inc. - Inventors: Stephen Marrou; Xiangyang Zhu; Heqing Huang - Web page: https://patentgrep.com/patent/US10501625B2 ## CPC - C08L 71/02: Polyalkylene oxides - C08F 2/32: Polymerisation in water-in-oil emulsions - C08F 220/56: Acrylamide; Methacrylamide - C08F 222/38: Amides - C09K 8/588: characterised by the use of specific polymers {(polymeric surfactants C09K8/584)} - C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06) - C08F: MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS - C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE ## Abstract A method of making acrylamide-acrylic acid copolymers in water-in-oil latices is described. The method results in a copolymer having randomly distributed carboxylate functionalities and is suitable for ionic crosslinking. The copolymers and their ionically crosslinked counterparts are useful for enhanced oil recovery processes. ## Claims ### Claim 1 A composition comprising a water-in-oil latex, the water-in-oil latex comprising a water phase and an oil phase, the water phase comprising water and monomers, the monomers consisting of acrylamide and acrylic acid, wherein the pH of the water phase is about 3.0 to 4.5; wherein the latex further comprises a surfactant mixture consisting essentially of nonionic surfactants and comprising a block copolymer. ### Claim 2 (depends on 1) The composition of claim 1 wherein the ratio of acrylamide to acrylic acid is about 60:40 to 99:1. ### Claim 3 (depends on 1) The composition of claim 1 wherein the block copolymer is a triblock copolymer comprising at least one block consisting essentially of ethylene glycol repeat units and having an HLB of about 4 to 6. ### Claim 4 (depends on 3) The composition of claim 3 wherein the triblock copolymer further comprises at least one block consisting essentially of hydroxyacid repeat units. ### Claim 5 (depends on 4) The composition of claim 4 wherein the hydroxyacid is 12-hydroxystearic acid. ### Claim 6 (depends on 1) The composition of claim 1 wherein the pH is about 3.5 to 4.0. ### Claim 7 A composition comprising a water-in-oil latex formed by a method comprising a. combining water and monomers to form a water phase, the monomers consisting of acrylamide and acrylic acid; b. adjusting the pH of the water phase to between about 3.0 to 4.5; c. combining a hydrocarbon solvent with a surfactant mixture to form an oil phase, the surfactant mixture consisting essentially of nonionic surfactants and comprising a block copolymer; d. contacting the water phase and the oil phase to form a water-in-oil latex; e. polymerizing the monomers to form a copolymer; and f. neutralizing the water phase. ### Claim 8 (depends on 7) The composition of claim 7 further comprising the product of diluting the composition with a water source after neutralizing, wherein the copolymer concentration after diluting is about 0.01 wt % to 1.00 wt %. ### Claim 9 (depends on 8) The composition of claim 8 wherein the water source comprises water and a salt of Ca2+, Fe+2, Fe+3, Mg2+, Cr2+, Cr3+, Zn2+, or Al3+. ### Claim 10 (depends on 9) The composition of claim 9 wherein the salt is aluminum citrate or chromium acetate. ### Claim 11 (depends on 7) The composition of claim 7 wherein the ratio of acrylamide to acrylic acid units in the copolymer is about 50:50 to 99:1. ### Claim 12 (depends on 7) The composition of claim 7 wherein the neutralizing comprises contacting the composition with sodium hydroxide and an alkanolamide surfactant. ### Claim 13 (depends on 12) The composition of claim 12 wherein the alkanolamide surfactant is N,N-diethanololeamide. ### Claim 14 A method of making a water-in-oil copolymer latex, the method comprising a. combining water and monomers to form a water phase, the monomers consisting of acrylamide and acrylic acid; b. adjusting the pH of the water phase to between about 3.0 to 4.5; c. combining a hydrocarbon solvent with a surfactant mixture to form an oil phase, the surfactant mixture consisting essentially of nonionic surfactants and comprising a block copolymer; d. contacting the water phase and the oil phase to form a water-in-oil latex; e. polymerizing the monomers to form a copolymer; and f. neutralizing the water phase. ### Claim 15 (depends on 14) The method of claim 14 further comprising diluting the latex with a water source after neutralizing, wherein the copolymer concentration after diluting is about 0.01 wt % to 1.00 wt %. ### Claim 16 (depends on 15) The method of claim 15 wherein the water source comprises water and a salt of Ca2+, Mg2+, Cr2+, Cr3+, Zn2+, or Al3+. ### Claim 17 (depends on 16) The method of claim 16 wherein the salt is aluminum citrate or chromium acetate. ### Claim 18 (depends on 14) The method of claim 14 wherein the neutralizing comprises contacting the composition with a neutralizing solution, the neutralizing solution comprising sodium hydroxide and an alkanolamide surfactant. ### Claim 19 (depends on 14) A method of diluting a water-in-oil copolymer latex, the method comprising adding a water source to the water-in-oil copolymer latex of claim 14 after the neutralizing, wherein the water source comprises water and a salt of Ca2+, Mg2+, Cr2+, Cr3+, Zn2+, or Al3+; and the copolymer concentration after diluting is about 0.01 wt % to 1.00 wt %.