Double propagation based on diepoxide, a facile route to high molecular weight poly(propylene carbonate)

Poly(propylene carbonate) (PPC) with number average molecular weight (Mn) higher than 200 kg/mol was prepared via the terpolymerization of carbon dioxide, propylene oxide and diepoxide using Y(CCl3OO)3–ZnEt2–glycerine coordination catalyst. When equimolar ZnEt2 and diepoxide were used, double propagation active species were generated in situ by nucleophilic attack of metal alkoxide on diepoxide, leading to PPC of doubled Mn value. The molecular weight of PPC has dramatic influence on its thermal and mechanical performances. PPC with Mn of 227 kg/mol showed modulus of 6900 MPa, while the modulus of PPC with Mn of 109 kg/mol was only 4300 MPa. Moreover, when Mn increased from 109 to 227 kg/mol, a 37 °C increase of the onset degradation temperature was observed.