Patent ID: 7932339
Filing Date: 2011-04-26
Classification: C08F,G01N

Abstract:
1. A process for preparing a comb copolymer of which the backbone is of the acrylamide, acrylic acid, acryloylaminoethanol or dimethylacrylamide type, grafted onto which are poly(N-alkylacrylamide) or poly(N,N-dialkylacrylamide) side segments, characterized in that it comprises the following successive steps: (a) preparation of a poly(N-alkylacrylamide) or poly(N,N-dialkylacrylamide) telomer of formula (I): in which n represents an integer greater than or equal to 2 and less than or equal to 100, Z represents a functional group capable of acting as a radical transfer agent, R 1 represents a divalent radical comprising from 1 to 4 carbon atoms, R 2 a hydrogen atom or a methyl group, R 3 a hydrogen atom or a linear or branched alkyl radical comprising from 1 to 4 carbon atoms and R 4 , being identical to or different from R 3 , represents a linear or branched alkyl radical comprising from 1 to 4 carbon atoms, by reaction in water of a compound of formula (II): in which R 2 , R 3 and R 4 are as defined above, with a chain-limiting compound of formula (III): in which Z represents a functional group capable of acting as a radical transfer agent in a (II)/(III) molar ratio less than or equal to n and greater than or equal to n/10, in the presence of a polymerization initiator; (b) isolation of the telomer of formula (I) obtained in step (a); (c) reaction, in water, of the telomer of formula (I) obtained in step (b), with the acid chloride of formula (IV): in which R 5 represents a hydrogen atom or a methyl radical, and in a (IV)/(III) molar ratio less than or equal to 10 and greater than or equal to 1 while keeping the pH of the reaction medium at a value between 6 and 13, preferably between 7 and 8, in order to obtain a macromonomer of formula (V): (d) isolation of the macromonomer of formula (V) obtained in step (c); (e) copolymerization, in water, of the macromonomer of formula (V) isolated in step (d) with a monomer chosen from acrylamide, acrylic acid, acryloylaminoethanol or dimethylacrylamide; and if desired (f) purification of the copolymer obtained.