Penta-Hydroxy Flavones-Based Photoinitiating Systems for Free Radical, Cationic, and Thiol-Ene Polymerization upon Exposure to Mild Blue LEDs

Natural flavone-derivatives (i.e., morin and quercetin) are investigated as visible light-sensitive photoinitiators. The photochemical mechanisms of the radical generation from flavone-derivative-based photoinitiating systems (PISs) upon exposure to mild blue light-emitting diodes are studied. The impact of substituent site of functional groups on the photoinitiation ability is determined. The quercetin-based PISs exhibit more reactivity than the morin-based systems on free radical photopolymerization. Moreover, the investigated flavone-based PISs present their stabilities at room temperature, indicating that resin containing these systems barely require special storage requirements. Thiol-ene polymerization initiated by the flavone-derivatives-based PISs is also investigated.