Synthesis and characterization of novel aliphatic polycarbonates

A new six-membered cyclic carbonate monomer, 5-benzyloxy-trimethylene carbonate, was synthesized from 2-benzyloxy-1,3-propanediol, and the corresponding polycarbonate, poly(5-benzyloxy-trimethylene carbonate) (PBTMC), was further synthesized by ring-opening polymerization in bulk at 150 °C using aluminum isobutoxide [Al(O i Bu) 3 ], aluminum isopropoxide, or stannous octanoate as an initiator. The results showed that a higher molecular weight polycarbonate could be obtained in the case of Al(O i Bu) 3 The protecting benzyl group was removed subsequently by catalytic hydrogenation to give a polycarbonate containing a pendant hydroxyl group (PHTMC). The polycarbonates obtained were characterized by Fourier transform infrared spectroscopy, 1 H NMR, 13 C NMR, gel permeation chromatography, and DSC. NMR results of PBTMC offered no evidence for decarboxylation occurring during the propagation. The pendant hydroxyl group in PHTMC resulted in an enhancement of the hydrophilicity of the polycarbonate.