Photochemical versus thermal thiol-ene “click chemistry” for renewable polyols with application in polyurethanes

The primary goal of the study was to compare the efficacy of two approaches, photochemical and thermal, in producing polyols from renewable soybean oil through thiol-ene reactions. The thiol-ene reaction was initiated with UV light in the presence of 2-hydroxy-2-methylpropiophenone as a photo-initiator or via a thermal pathway utilizing radical initiator 2,2′-Azobis(2-methylpropionitrile). The resulting polyols were analyzed using standard analytical techniques including Fourier transform infrared (FT-IR) and nuclear magnetic resonance (NMR) spectroscopies. It was observed that the polyols obtained through the photochemical route exhibited better outcome compared with those synthesized using the thermal treatment. Additionally, we employed computational chemistry technique using density functional theory (DFT) calculation to get insights into various product yields. The DFT results revealed that the hydrogen bond network likely contributed to the improved stability, hence obtained higher product yield of the polyol MSBO-TMPAE compared with that of MSBO-GAE. Our study also focuses on applying the synthesized polyols in polyurethane rigid foams and casts. The polyurethanes prepared from these polyols have comparable thermal and mechanical properties to that of the commercially available polyurethanes.