The Effect of Chain Extender Type on the Physical, Mechanical, and Shape Memory Properties of Poly(ε-Caprolactone)-based Polyurethane-ureas

A series of segmented polyurethane-ureas were synthesized, based on poly(ε-caprolactone), hexamethylenediisocyanate, and different chain extenders. The effect of chain extender on physical, mechanical, and shape memory properties of the polyurethane-ureas was examined at constant hard-to–soft–segment molar ratio. Polyurethane-urea from piperazine showed higher degree of phase separation, mechanical characteristics, shape fixity, and shape recovery temperature than polyurethane-ureas from aliphatic chain extenders. Furthermore, the degree of phase separation was decreased by increasing of chain length of aliphatic chain extenders. This was attributed to the dissimilar compatibility and flexibility of the hard segments, resulting from different chain extenders.