UV-induced cationic polymerization of oxetane and epoxidized vegetable oil-derived monomers

The increasing demand for sustainable coating technologies has driven interest in UV-curing systems due to their low energy consumption, rapid curing at ambient temperature, and VOC-free processing. Although cationic photopolymerization offers inherent advantages compared to radical systems, its application has been constrained by moisture inhibition, slow reaction rates, and limited bio-based monomer availability. This study provides insight into the photopolymerization mechanisms of oxetane and bio-based secondary epoxy monomers and demonstrates a formulation approach that enables fast curing with reduced sensitivity to environmental factors. The influence of epoxidized fatty acid methyl ester (EFAME) derived from rapeseed oil on oxetane-based systems was examined. Oxetane homopolymerization was found to be highly sensitive to the presence of water, whereas the incorporation of EFAME monomers effectively promotes the initiation of oxetane polymerization at ambient conditions. The results further show that copolymerization of oxetane and EFAME monomers significantly reduced sensitivity to air and moisture compared to oxetane homopolymerization and proceeded faster than EFAME homopolymerization. Efficient photopolymerization was achieved using a 365 nm LED light source. The study demonstrates that oxetane-epoxy copolymer systems incorporating bio-based EFAMEs offer improved curing kinetics and robustness, providing new opportunities for expanding cationic UV-curing towards more sustainable and industrially viable formulations. • Epoxidized fatty acid methyl esters kick-start oxetanes under ambient conditions. • Oxetane monomers co-polymerize well with secondary epoxides. • Photo-polymerization with 365 nm LED lamp