Development of a H3PW12O40/CeO2 catalyst for bulk ring-opening polymerization of a cyclic carbonate

Abstract

A new reaction system involving a heterogeneous H₃PW₁₂O₄₀/CeO₂ catalyst and methyl iodide initiator was developed for bulk ring-opening polymerization (ROP) of trimethylene carbonate (TMC). Combination of a Brønsted acid (H₃PW₁₂O₄₀) and Lewis base (CeO₂) had a synergic effect on a well-controlled ROP without decarboxylation, which gave poly(TMC) of molecular weight (M_n) 30 000 and Polydispersity Index (PDI) of 1.80 at 60 °C and 24 h. Fourier transform infrared (FTIR) spectroscopy elucidated a reaction mechanism in which H₃PW₁₂O₄₀ promoted the initiation reaction and CeO₂ activated TMC, and the interface of these two components was an active site for ROP. The catalyst was removed readily by filtrating a dimethyl carbonate solution of poly(TMC), which was confirmed by inductively coupled plasma-atomic emission spectroscopy. In addition, various kinds of biomass-derived poly(aliphatic carbonate)s were synthesized and thermal properties were investigated by differential scanning calorimetry and thermogravimetry-differential thermal analysis. In particular, pyrolysis-gas chromatography mass spectrometry of these polymers revealed that the degradation mechanism was highly dependent upon a small amount of ether linkages and a pendant methyl group.