Unimolecular Benzodioxole-based Photoinitiators for Free Radical and Cationic Photopolymerization Under LED Light Irradiation

Compared to amines as coinitiators applied in photopolymerization, benzodioxole derivatives exhibit similar reactivity but less yellowing and lower toxicity. In this paper, a series of unimolecular type II photoinitiators, containing coumarins chromophores benzodioxoles coinitiators, were synthesized. The substituents with different electron donating/withdrawing abilities designed for systematical investigation structure-property relationship. Under LED irradiation, the novel photoinitiators can induce not only free radical polymerization acrylate monomers, also cationic epoxy monomers via promoted mechanism.