Water-based process for the preparation of polymer-clay nanocomposites
First Claim
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1. A method of preparing a nanocomposite comprised of an elastomer and at least partially exfoliated platelets from a water-swellable clay which comprises blending:
- (A) an aqueous latex comprised of an amphiphilic block copolymer prepared by(1) preparing a first aqueous polymerization medium which is comprised of(a) 4-vinylpyridine,(b) a trithiocarbonate RAFT agent, and an emulsifier, wherein the emulsifier is prepared in-situ within the aqueous polymerization medium by the reaction of a latent surfactant with a surfactant activator;
(2) polymerizing the 4-vinylpyridine within the first aqueous polymerization medium in the presence of a first free radical initiator to produce a poly(4-vinylpyridine);
(3) protonating the poly(4-vinylpyridine) to form a protonated poly(4-vinylpyridine) RAFT macroinitiator;
(4) preparing a second aqueous polymerization medium which is comprised of the protonated poly(4-vinylpyridine) RAFT macroinitiator and a monomer containing ethylenic unsaturation but is exclusive of a surfactant; and
(5) polymerizing the protonated poly(4-vinylpyridine) RAFT macroinitiator and monomer containing ethylenic unsaturation within the second aqueous medium in the presence of a second free radical initiator and a temperature less than 100°
C. to produce an amphiphilic block copolymer of the 4-vinylpyridine and monomer containing ethylenic unsaturation;
(B) an aqueous mixture of water and a multilayered water-swellable clay which contains cationically exchangeable ions in its galleries between said layers, exclusive of an intercalant for said clay, wherein said water-swellable clay is comprised of a plurality of stacked platelets with water-swollen galleries between said platelets, wherein said galleries contain cationic ion exchangeable ions therein.
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Abstract
This invention relates to an aqueous based process for the preparation of intercalated and/or exfoliated natural or synthetic clays using block copolymers in latex form containing at least one non-polar block and one or more cationic blocks, wherein the block copolymers are prepared by an emulsion controlled free radical polymerization method.
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20 Claims
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1. A method of preparing a nanocomposite comprised of an elastomer and at least partially exfoliated platelets from a water-swellable clay which comprises blending:
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(A) an aqueous latex comprised of an amphiphilic block copolymer prepared by (1) preparing a first aqueous polymerization medium which is comprised of (a) 4-vinylpyridine, (b) a trithiocarbonate RAFT agent, and an emulsifier, wherein the emulsifier is prepared in-situ within the aqueous polymerization medium by the reaction of a latent surfactant with a surfactant activator; (2) polymerizing the 4-vinylpyridine within the first aqueous polymerization medium in the presence of a first free radical initiator to produce a poly(4-vinylpyridine); (3) protonating the poly(4-vinylpyridine) to form a protonated poly(4-vinylpyridine) RAFT macroinitiator; (4) preparing a second aqueous polymerization medium which is comprised of the protonated poly(4-vinylpyridine) RAFT macroinitiator and a monomer containing ethylenic unsaturation but is exclusive of a surfactant; and (5) polymerizing the protonated poly(4-vinylpyridine) RAFT macroinitiator and monomer containing ethylenic unsaturation within the second aqueous medium in the presence of a second free radical initiator and a temperature less than 100°
C. to produce an amphiphilic block copolymer of the 4-vinylpyridine and monomer containing ethylenic unsaturation;(B) an aqueous mixture of water and a multilayered water-swellable clay which contains cationically exchangeable ions in its galleries between said layers, exclusive of an intercalant for said clay, wherein said water-swellable clay is comprised of a plurality of stacked platelets with water-swollen galleries between said platelets, wherein said galleries contain cationic ion exchangeable ions therein. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification