Alternative copolymerization of aziridines and carbon monoxide by γ‐ray irradiation

Abstract

Abstract The copolymerization of carbon monoxide and aziridines such as ethylenimine and propylenimine was carried out by γ‐ray irradiation. Aziridines and carbon monoxide were allowed to copolymerize under γ‐ray irradiation from a Co 60 source and gave a crystalline solid copolymer. The yield of the copolymer increased with reaction temperature. The composition of copolymers obtained did not depend on the feed ratio of monomers and was found to be almost equimolar. The copolymer of ethylenimine and carbon monoxide melted at about 322–335°C. with decomposition and has an infrared spectrum identical with that of poly‐β‐alanine obtained by the hydrogen‐migration polymerization of acrylamide. The hydrolyzed product of the ethylenimine–carbon monoxide copolymer was confirmed to be β‐alanine by paper chromatography. These results lead to the conclusion that the copolymerization of aziridines and carbon monoxide took place alternatively by γ‐ray irradiation, and produced crystalline poly‐β‐alanines.