A One-Pot Synthesis of a Triblock Copolymer from Propylene Oxide/ Carbon Dioxide and Lactide: Intermediacy of Polyol Initiators

摘要

The energy and environmental concerns of petroleum-based plastics have stimulated the development of new polymeric materials that incorporate renewable resources. Synthesis of polymers by copolymerization of CO2 and epoxides offers the possibility of providing a wide variety of degradable polycarbonates. In contrast to the alternative route of condensation polymerization, which involves the use of toxic phosgene or its derivatives, this process represents an environmentally benign approach. Since the seminal discovery by Inoue et al. in 1969 , numerous well-defined catalyst systems developed for the CO2/epoxide copolymerization have resulted in greatly suppressing ether linkages, increasing polymer selectivity, and controlling molecular-weight distributions. Although these reported studies are very significant and impressive, current attempts at the industrialization of this green technology are limited to ethylene oxide and propylene oxide to produce poly(ethylene carbonate) and polypropylene carbonate), Moreover, the relatively low T_g value (< 35 °C) of these kind of polymers further thwart their use as commercial thermoplastics. Therefore, the synthesis of more diverse CO2-based copolymers to improve material performances as well as categories of this greener polymer is an important and challenging topic for research and development.