Studies of structure and properties of photocrosslinked polyurethane acrylates

A series of ultraviolet‐induced photocrosslinkable polyurethane acrylates was synthesized. They are composed of a polyether [poly(propylene oxide) or poly(tetramethylene oxide)] soft segment and two terminal hard segments derived from 2‐hydroxyethyl methacrylate and a diisocyanate. Based on stress‐strain and DSC measurements of their UV‐cured materials, relations between their structure and physical properties were investigated systematically. The results show that parameters which increase the content of hard segments and the crosslinking density of UV‐cured materials lead to an increase in Young's modulus and stress at break accompanied by a decrease in elongation at break. The glass transition temperature of the polyether soft segment is determined mainly by the type and molecular weight of the polyether, due to a two‐phase morphology.