PEGylated poly(2-(dimethylamino)ethyl methacrylate) with comb-like architecture was synthesized by two-step polymerization.First,poly(oligo(ethylene glycol) malicate) (POEGMA) bearing pendant hydroxyl groups was prepared by direct polycon-densation of oligo(ethylene glycol) and rnalic acid in the presence of scandium triflate as chemoselective catalyst.Then the poly(2-(dimethytamino)ethyl methacrylate) side chains were grafted from the POEGMA backbone by atom transfer radical polymerization (ATRP) after the hydroxyl groups were modified into bromo-ester form,resulting in a PEGylated cationic copolymer with branched architecture.