CRYSTALLINITY AND HYDROGEN-BONDING OF HARD SEGMENTS IN SEGMENTED POLY(URETHANE UREA) COPOLYMERS

Polyurea hard segment model compounds and a series of segmented poly(u rethane urea) (SPUU) copolymers, with hard segment content ranging fro m 18.8-91.0%, were synthesized based on 4,4'-diphenylmethane diisocyan ate (MDI), 3,5-diethyltoluenediamine (DETDA), and ethylene-oxide-cappe d poly(propylene oxide) polyether diol (PPO). By analysis of model com pounds, crystallization of DETDA-MDI hard segments was confirmed and r elationships between urea hydrogen bonding with morphological changes were suggested. The crystallization, however, was not complete in the copolymers even when the hard segment content was high. New spectral e vidence for phase inversion is presented. Fourier transform infra-red analysis suggested that the equilibrium of urea hydrogen bonding betwe en crystalline region and amorphous regions was affected mainly by mor phological changes (phase inversion) and was almost independent of che mical composition of the SPUU copolymers under certain morphological c onditions both before and after phase inversion. Copyright (C) 1996 El sevier Science Ltd.