Synthesis of UV rapid curing silicone coatings via photoinitiated thiol-ene click polymerization for pressure-sensitive adhesive

UV-curable silicone pressure-sensitive adhesive (SPSA) is composed of silicone rubber and silicone resin. Generally, the C=C double bond in acryloyloxy group provides a photocurable group for SPSA. However, oxygen inhibition of acryloyloxy group block the degree of cure and C=C double bond conversion of SPSA during the photopolymerization. Therefore, efficient photocurable groups for UV curing SPSA is particularly important to be developed. Thiol-ene click polymerizations have been widely used in photocrosslinked polymers due to the rapid efficiency of reactions. In this study, sulfhydryl functionalized silicone resin (SFSR) and methacrylate func-tionalized amino silicone rubber (MFASR) were synthesized to prepare a SPSA via photoinitiated thiol-ene click polymerization. The double bond in MSASR and sulfhydryl in SFSR were characterized by FT-IR spectroscopy and H-1 NMR spectroscopy. The double bond conversion of SPSA was calculated after polymerization. The cohesion of SPSA was improved by SFSR, while the crosslinking degree was improved by thiol-ene. The loop tack of SPSA with 50 wt% SFSR was 9.01 N, and the 180 peel strength was 11.37 N/25 mm. The SPSA maintained good bonding adhesion to steel at various temperature.