Poly(ethylene carbonate)s, part I: Syntheses and structural effects on biodegradation

Poly(ethylene carbonate)s (PECs) of different molecular weights (Mws) were synthesized by copolymerization of CO2 and ethylene oxide using different catalyst systems. Et2Zn/ethylene glycol was found to be exceptionally effective as a catalyst for this copolymerization. PECs synthesized using this catalyst were characterized by very high ethylene carbonate content, low polydispersity and high glass transition temperatures. The in vivo biodegradability of PECs was found to be affected by the content of ether functions in the polymer chain, by the Mw of the products and by the catalyst used to prepare them. Surprisingly, the biodegradation of PECs having Mws<100 000 is strongly suppressed, whilst PECs with Mw>130 000 show almost identical in vivo biodegradation by surface erosion. (C) 1997 Elsevier Science B.V.