Photo-induced Energy Transfer Polymerization

In conventional photo-induced polymerization strategies, the active species that initiate the reaction tend to be exogenous radical species. Inspired by photo-induced cycloaddition reactions, in this study we investigated photo-induced polymerization from the perspective of energy transfer processes. Utilizing low-energy, highly reactive triplet species of olefin molecules as energy acceptors, a polymerization strategy without the need for exogenous active components was developed. Triplet species from various sources were able to induce polymerization, demonstrating the excellent versatility of this strategy. The reaction mechanism was thoroughly investigated with controlled experiments and spectroscopic methods using thiochromanone as a template. It was clearly established that the key to polymerization is an active triplet species rather than a conventional radical species. As a result, the findings of this study stimulate further discussion on the role of monomers in photo-induced polymerization.