Preparation of urethane-acrylates by the photo-polymerization of acrylate monomers using a benzophenone initiator grafted onto a polyurethane copolymer

Photo-polymerization of the acrylate monomers, butylacrylate or 2-hydroxyethyl methacrylate, was initiated by polyurethane (PU) grafted benzophenone to prepare a series of urethane acrylate (UA) polymers. The UA polymers were characterized based on their thermal, spectroscopic, mechanical, and low temperature flexibility properties. In this system, poly(acrylate) chains grew from the grafted benzophenone by photo-polymerization and affected the molecular interactions between PU polymers. The soft segment glass transition temperature (T (g) ) and melting temperature (T (m) ) were unaffected by the grafted poly(acrylate) chains. The tensile mechanical strength and the tensile strain of the UA series increased significantly with the attachment of the poly(acrylate) chains. Furthermore, shape recovery and shape retention remained high as the test cycle was repeated. Low temperature flexibility testing demonstrated that the synthesized UA was more flexible at a lower temperature than the unmodified PU.