Shape memory polyurethane containing amorphous reversible phase

Segmented thermoplastic polyurethanes (TPUs), which consist of an amorphous soft segment from 1,3-butanediol and hexamethylene diisocyanate (HDI) and a crystalline hard segment from 4,4′-bis-(6-hydroxy hexoxy)biphenyl and tolylene 2,4-diisocyanate were synthesized. Their thermal and mechanical properties, shape memory effect, utilizing amorphous soft segment domain as reversible phase and crystalline hard segment domain as frozen phase, were examined. The reversibility observed on repeated deformation was improved as the magnitude of deformation was reduced and the hard segment content was increased, or by crosslinking with excess HDI.