Agent for obtaining a stable aqueous composition comprising a polymer constituted of: at least one A monomer of acrylic acid and/or methacrylic acid and/or any of their salts, at least one B monomer of alkyl acrylate and/or methacrylate, and at least one C monomer corresponding to the following formula (I): T-[(EO)n(PO)n&prime(BO)n&Prime]-Z &emsp&emsp(I) &emspin which: T represents one end enabling the co-polymerization of the C monomer, [(EO)n(PO)n&prime(BO)n&Prime] represents a polyalkoxylated chain constituted of alkoxylated units, distributed into blocks, alternatively or statistically, chosen from among EO ethoxylated units, PO propoxylated units and BO butoxylated units, representing, independently from each other, 0 or a whole number between 1 and 150, the sum of n, -n&prime and n&Prime not being null, and Z represents a fatty chain, linear or branched, of at least 16 carbon atoms, at least one crosslinked monomer D.
