Synthesis and Characterization of Biodegradable Homopolymers and Block Copolymers Based on 1,5-Dioxepan-2-one

Homopolymers of 1,5-dioxepan-2-one (DXO) and block copolymers of DXO and e-caprolactone (e-CL) have been synthesized with aluminum isopropoxide as an initiator in toluene and THF. The homopolymerization is first order with respect to both monomer and initiator, and the end-group analysis agrees with a coordination insertion mechanism based on the acyl-oxygen cleavage of the DXO ring. Living poly(e-caprolactone) (PCL) and poly(1,5-dioxepan-2-one) (PDXO) chains are very efficient macroinitiators for the polymerization of DXO and e-CL, respectively, with formation of block copolymers of a narrow molecular weight distribution