Naphthalimide-Tertiary Amine Derivatives as Blue-Light-Sensitive Photoinitiators

The photochemical mechanism of the radical generation from photoinitiating systems based on 1, 8-naphthalimide derivatives (ANDs; with tertiary amine moieties) are investigated by using various approaches including cyclic voltammetry, steady-state photolysis, and electron spin resonance spin-trapping techniques. It reveals that radicals can be produced from ANDs alone or ANDs/additive (e. g. iodonium salt or chloro triazine) combinations. The generated radicals and cations can initiate both free-radical and cationic photopolymerization reactions under irradiation with various light-emitting diodes or a halogen lamp. For most of the AND-based photoinitiating systems, more than 60 % of acrylate or epoxide conversions were attained, and were even higher than those obtained by using commercial photoinitiators, for example, bisacylphosphine oxide or camphorquinone. More interestingly, the AND1-based photoinitiating system can also initiate concomitant cationic/radical polymerizations and can be used for the synthesis of interpenetrated polymer networks.