Cardanol-Based Polyurethane Coatings via Click Chemistry: An Eco-friendly Approach

This research work discloses the preparation of polyurethane coatings from cardanol modified using thiol-ene chemistry, wherein unsaturated long alkyl chain of cardanol was successfully utilized via thiol-ene click reaction to synthesize polyol. For this purpose, cardanol and thioglycerol was reacted in the presence of Irgacure 184 (photoinitiator) and 1,8-Diazabicyclo[5.4.0]undec-7-ene (catalyst) and exposed to UV light for 12 h at 80 degrees C. One mole of thioglycerol was successfully added across the double bond of fatty chain of cardanol and confirmed by chemical and spectroscopic analysis. Further, the polyol thus prepared was cured with various polyisocyanates, viz., N-75 (HDI based), L-67/BA (TDI based), Z-4470 (IPDI based) and corresponding polyurethane coatings were developed. The coatings were then analyzed for mechanical, chemical, optical, thermal and anticorrosive properties. It was observed that cardanol-based PU coatings exhibited excellent mechanical, chemical and thermal and anticorrosive properties as compared to that of commercial acrylic-PU coatings.