An anionic polyelectrolyte resulting from the polymerization, for 100% by mass of: a) a mass ratio ≧70% and ≦98.5% of monomeric units from a monomer with a strong acid function； b) a mass ratio ≧0.5% and ≦10%, —either of a monomer of formula (1a) : R—(CH2)3-Si(CH2)2-[0-Si(CH3)2-]nO—Si(CH3)2—(CH2)3—R (1a), wherein R represents the monovalent radical: -(0-CH2-CH2-)x[0-CH2—CH(CH3)-]yO—C(═0)-CH═CH2；—or (Ib): Si(CH3)3-[0-Si(CH3)2-]m[0-Si(CH3)[(CH2)3—R]—]pO—Si(CH2)3 (Ib), c) a mass ratio ≧1% and ≦20% of a monomer of formula (II) : CH2═CH(R1)-C(═0)-0-(CH2)n-CF3 (II), formula (I) wherein radical Ri represents a hydrogen atom or a methyl radical, and n is equal to 1, 2 or 3； d) optionally a mass ratio >；0% and ≦5% of monomeric units from a monomer of formula (III): R2—C(═0)-0-[(CH2—CH(R4)-0]m-R3 (III), e) optionally a mass ratio >；0% and ≦5% of a cross-linking monomer, method for its preparation and use as a thickener in topical compositions.
