Preparation of copoly(carbonate/urethanes) from polycarbonates

Abstract

Abstract When solutions of high molecular weight poly(diphenylolpropane carbonate) were treated with aliphatic primary and secondary diamines in a homogeneous system, degradation to hydroxyl‐terminated copoly(carbonate/urethane) macrosegments occurred. This observation led to a novel method for the preparation of high molecular weight copoly(carbonate/urethanes). This involved ( 1 ) preparation of high molecular weight polycarbonate, ( 2 ) degradation of the polycarbonate to a low molecular weight urethane‐bisphenol, ( 3 ) repolymerization with phosgene. The composition of the final copolymer could be regulated by the amount of diamine empolyed in step ( 2 ). High molecular weight copolymers were thus prepared from poly(diphenylolpropane carbonate) and piperazine, ethylene diamine, hexamethylene diamine, p ‐xylylene diamine and hydrazine. These copolymers could be converted to tough drawable films which showed greatly improved hydrolytic stability over unmodified poly(diphenylolpropane carbonate).