Synthesis, curing process and thermal reversible mechanism of UV curable polyurethane based on Diels-Alder structure

A novel polyurethane resin containing acrylate function and Diels-Alder (DA) structure was synthesized, with potential thermal reversibility and UV curable properties. The UV curing process was monitored by Fourier transform infrared spectroscopy (FTIR), which indicated that the DA structure was stable during curing process and the final acrylate CC conversion is 82.5%. The cured film exhibited good repeatedly thermal reversibility. The retro-Diels-Alder (rDA) reaction of the cured film occurred at temperatures higher than 85.5 °C and was obviously accelerated by increasing temperature, which was confirmed by the results of FTIR, differential scanning calorimeter (DSC) and dynamic thermomechanical analysis (DMA). The cured film displayed acceptable thermal stability up to 278.3 °C according to the thermal gravimetric analysis (TGA) results. Finally, a cured film with excellent physical properties was obtained.