Synthesis and characterization of a photo-crosslinkable polyurethane based on a coumarin-containing polycaprolactone diol

Abstract A new coumarin diol was designed and used as initiator for the ring opening polymerization of e-caprolactone. A photo-reactive polyurethane based on the resulting polycaprolactone diol with pendant coumarin moieties was synthesized. Photo-dimerization/photocleavage reactions were studied by UV and Raman. The linear non-irradiated soft polyurethane transformed into a tough elastomeric crosslinked material. DQ-NMR measurements showed that conversion of the photo-reaction was not directly related to relative amount of crosslinking but provided complementary information. Crosslinking reduced the crystallinity of the polycaprolactone segments and the melting point of the crystals.