SYNTHESIS OF THERMORESPONSIVE POLY(URETHANE-AMINE)S FROM 2-METHYLAZIRIDINE AND CARBON DIOXIDE CATALYZED BY NATURAL AMINO ACIDS

摘要

Based on the viewpoint of environmental protection, relative development of the fixation and usage of carbon dioxide as cheap C1 raw material has been drawing much attention in industrial chemistry and bio-technology. Since the pioneering work of Inoue in 1969 that carbon dioxide copolymerized with alkene oxides to yield aliphatic polycarbonates, chemical fixation of CO_2 has been greatly developed in the past four decades, while copolymerization of CO_2 and cyclic imines to give poly(urethane-amine)s was just of little attention for kinds of reasons. Aliphatic poly(urethane-amine)s (PUA) were synthesized from copolymerization of CO_2 and 2-methylaziridine (MAZ) with natural amino acid as catalyst. Compared to metal complexes, amino acids are cheap, available, biocompatible and nontoxic. PUA was thermo-responsive in distilled water, and the lower critical solution temperature (LCST) was dependent on both urethane content and molecular weight. There was a great discrepancy in performance for PUA obtained from different amino acids. We speculate that the substitute of amino acid plays a vital role in the reaction. Sanyo Chemical Industries Ltd. is greatly acknowledged for providing partial financial supports to the work.