抄録
A commercially available carbonate oligomer, poly(hexamethylene/ pentamethylene carbonate) (PHPC), was found to involve various minor units that had been formed during the ester-exchanging polycondensation of ethylene carbonate and a mixture of 1,6-hexanediol and 1,5-pentanediol. This PHPC oligomer was chain-extended by using diphenyl carbonate as chain extender and then subjected to tin-catalyzed ring-opening polymerization of L-lactide to prepare ABA tri-block copolymers consisting of poly-L-lactide (PLLA) and PHPC as the hard A and soft B blocks, respectively. With the chain-extended PHPC as the macro-initiators, the molecular weights of the resultant copolymers became significantly higher even at increased contents of PHPC. The tri-block copolymers obtained were fabricated into polymer films by solution casting, and their properties were analyzed. It was revealed that the tri-block copolymers PLLA-PHPC-PLLA can be novel thermoplastic elastomers that are environmentally friendly in terms of utilization of carbon dioxide as feedstock.
