A comb copolymer having a backbone of 2-acrylamido-2-methylpropanesulfonic acid or a derivative thereof, with grafted lateral side segments of poly(N-alkylacrylamide) or poly(N,N-dialkylacrylamide), is provided. A process for the preparation of the comb copolymer includes reacting a compound of formula (II) with a compound of formula (III) in a (tert-butanol)-water mixture, to obtain a poly(N-alkylacrylamide) or poly(N,N-dialkylacrylamide) telomere of formula (I); reacting in tert-butanol the telomer of formula (I) with an acid chloride of formula (IV) to obtain a solution of the macromonomer of formula (V); and copolymerising in tert-butanol the macromonomer of formula (V) with an ammonium salt of 2-acrylamido-2-methylpropanesulfonic acid.