alpha-Chloromethyl-alpha-methyl-beta-propionolactone (CMMPL) has been copolymerized with epsilon-caprolactone (CL) using a wide range of feed compositions and aluminium triisopropoxide [Al((OPr)-Pr-i)(3)] as an initiator. Random copolymers of CMMPL with CL were obtained. The pendant chloromethyl groups of the copolymer were converted to quaternary ammonium salts by reaction with pyridine, resulting in an increased hydrophilicity of the copolymers.