The AB diblock copolymers, Me-PEG-PLLA and Me-PEG-PDLA, were prepared by the ring-opening copolymerization of L-lactide and D-lactide, respectively, in the presence of Me-PEG. Since each of the resultant AB diblock copolymers contained a considerable amount of triblock copolymer, PLLA-PEG-PLLA or PDLA-PEG-PDLA, high osmotic pressure chromatography was conducted to separate off the triblock copolymers. The purified diblock copolymers were then examined for hydrogel formation
