Synthesis and properties of block copolymer comprising of poly(DL-lactic acid) and poly(ethylene oxide)

The block copolymers were prepared by the ring opening polymerization of DL-lactide by poly(ethylene oxide) (PEO) with diethylzinc (ZnEt2) as a catalyst. When the feed ratio of PEO was over 30% relative to DL-lactide, the polymerization of Dl-lactide took place from the PEO hydroxyl terminals to provide the desired A-B-A or A-H block copolymer. The block copolymers were made of films by cast method and the films obtained was drawn to 2.5 times at 60 degreesC. At the same draw ratio, the tensile moduli-is of the films was decreased with increasing PEO content in the block copolymers. It was therefore suggested that the block copolymers comprising of PDLLA and PEO, had high potentials as the biomaterials with improved flexibility.