Preparation of temperature-sensitive polyurethanes for smart textiles

A series of segmented polyurethane (P U) were prepared using five different polyols and hexamethylene diisocyanate (HDI) as mixing soft segment, 4,4'-diphenylmethane diisocyanate, hydrophilic segment poly (ethylene glycol) 200 (PEG 200) and chain extender 1,4-butanediol (1,4-BDO) as triblock hard segment. The microstructure of the PUs was investigated by differential scanning calorimetry, wide-angle X-ray, and polarizing microscopy. Tensile property was measured, and the water vapor transport property of the PU membranes as a function of temperature was tested accordingly. It was found that the PUs with crystalline soft segments were temperature-sensitive; that is, crystal melting of soft segment results in the significant increase in water vapor permeability of the PU membranes. Proper molecule design can set switch temperature ranges in water vapor permeability of the membranes from 10 to 40 degrees C including body temperature. Such properties can contribute to the development of smart textiles.