Temperature sensitive water vapour permeability and shape memory effect of polyurethane with crystalline reversible phase and hydrophilic segments

Polyurethanes based on poly(caprolactone) (PCL) diol, hexamethylene diisocyanate, 4,4′-diphenylmethane diisocyanate and hexamethylene diamine were modified by hydrophilic segments, diol-terminated poly(ethylene oxide) or dimethylol propionic acid (DMPA). Differential scanning calorimetry, dynamic mechanical tests, tensile tests, and measurement of water vapour permeability were carried out to characterize these polyurethanes. Temperature sensitive water vapour permeability, that is, the abrupt increase of water vapour permeability at the melting temperature of the PCL phase, was enhanced by modification with hydrophilic segments. Fatigue in shape memory effects was minimized by introducing some amount of DMPA units into the polyurethane chain. © 2000 Society of Chemical Industry