Synthesis and hydrolytic degradation of aliphatic polycarbonate based on dihydroxyacetone

Abstract

The six-membered cyclic carbonate monomer, 2,2-dimethoxy-1,3-propanediol carbonate based on dihydroxyacetone with methanol ketal protected carbonyl group, was prepared by a two-step reaction including protection and ring-closing, starting from dihydroxyacetone. The ring-opening polymerization of 2,2-dimethoxy-1,3-propanediol carbonate was carried out in bulk at 110–140°C initiated by stannous octanoate to give polycarbonate, poly(2,2-dimethoxypropane-1,3-diol carbonate). The effects of different reaction conditions including different catalyst, reaction temperature, molar ratio of monomer to initiator and polymerization time on the polymerization were investigated. Polycarbonate was obtained with the yield of 58.9–91.0%. The number average molecular weight of polycarbonate was in the range of 1.43 × 10⁴ to 13.82 × 10⁴ with polydispersity indexes from 1.31 to 1.91. The protecting ketal group was partly removed by hydrolysis using 50% trifluroacetic acid as a catalyst to give a functional polycarbonate containing 70% ketone carbonyl group, which improved the hydrophilicity of initial polycarbonate. The in vitro degradation tests were carried out in a phosphate buffer solution with pH 7.4 at 37°C, which showed that the modified polycarbonate degraded completely after 5 days.