A comb copolymer consisting of a polymer backbone on which lateral macromonomer segments are grafted, characterised in that said polymer backbone consists: Of more than 55% and up to 90% molar of monomeric units from 2-methyl-2-[(1-oxo-2-propenyl)-amino]-1-propanesulphonic acid (hereinafter referred to as ATBS), Of between 1% and 20% molar, and more specifically of between 4% and 15% molar, either of monomeric units from a cationic monomer or of monomeric units from a monomer of formula (I): CH2═C(R1)—C(═O)—Y—(CH2)m-N(R2)(R3) in which m represents a number of between 1 and 4, Y represents O or NH, R-i represents a hydrogen atom or a methyl radical, R2 and R3, identical or different, represent a methyl radical or an ethyl radical Optionally of 0.005% molar to 1% of monomeric units from at least one cross-linking monomer comprising at least two carbon-carbon double bonds, and in that said lateral macromonomer segments are, for 100% molar constituting said comb copolymer, derived from the polymerisation of 9% to 30% molar of N-alkyl acrylamide or N,N-dialkyl acrylamide of formula (II): CH2═C(R4)—C(═O)—N(R5)(R6), in which R4 represents a hydrogen atom or a methyl radical and R5 and R6 represent, independent of each other, a hydrogen atom or an alkyl radical comprising 1 to 3 carbon atoms, it being understood that at least one of the R5 or R6 radicals does not represent a hydrogen atom, the method for the preparation and the use thereof as a thickener in cosmetics.
