Design of High Performance Photoinitiators at 385–405 nm: Search around the Naphthalene Scaffold

Abstract

Novel naphthalene derivatives have been designed to be used as versatile photoinitiators upon a laser diode (405 nm), a polychromatic halogen lamp, or an UV LED (385 nm) exposure. The reactive species produced from photoinitiating systems based on one particular naphthalene derivative (NA3) and an iodonium salt, N-vinylcarbazole, an amine or 2,4,6-tris(trichloromethyl)-1,3,5-triazine were particularly efficient for cationic, radical, IPN and thiol–ene photopolymerizations upon low light intensity exposure. The best proposed systems exhibit a higher efficiency than references systems for visible lights (i.e., camphorquinone CQ-based photoinitiating systems). The mechanisms for the photochemical generation of reactive species (i.e., radicals and cations) were studied by electron spin resonance spin-trapping, fluorescence, cyclic voltammetry, laser flash photolysis, and steady state photolysis techniques.