Synthesis of grafted polysilsesquioxane by ring-opening polymerization of lactide and trimethylene carbonate

The polysilsesquioxane (PSQ) containing 3-aminopropyl and phenyl groups (APSQ) was prepared from the corresponding trimethoxysilanes by co-condensation under basic conditions. The amino groups on APSQ were used as the initiator species for the graft polymerization of 1,3-trimethylene carbonate (TMC) and L-(-)-lactide (LA). The ring-opening polymerization of TMC and LA in the presence of the catalytic 1-trimethylsilylimidazole proceeded effectively to afford the PSQ with poly(TMC) and/or poly(LA) as the graft chains. The grafted PSQ containing poly(LA) showed the heat durability as an advantage of the hybrid polymer. In differential scanning calorimetry analysis, the grafted random copolymer of TMC and LA showed no clear endotherm corresponding to melting point (Tm). For the poly(LA)-grafted PSQ, the peak indicating Tm was observed in the first heating run, but the corresponding peak was very small in the second run.