Carboxymethylated lysine-based polymer and compositions comprising the same

A process for preparing a carboxymethylated lysine-based polymer, which comprises

• thermal polycondensation of monomers comprising
• (A) 60 to 95 mol % of lysine monomer,
• (B) 5 to 40 mol % of at least one dicarboxylic acid of formula (I) or amide-forming derivative thereof
• wherein
• R1 is a direct bond or an aliphatic linear hydrocarbylene, which is unsubstituted or substituted with at least one group selected from the group consisting of unsubstituted or substituted alkyl, unsubstituted or substituted alkoxy, unsubstituted or substituted alkylthio, unsubstituted or substituted alkylamino, di(alkyl)amino, alkylidene, hydroxyl, mercapto, amino and halogen,
• to obtain a lysine-based polymer, and
• carboxymethylation of the lysine-based polymer.