Cationic photosensitive formulations based on silyl radical chemistry for green and red diode laser exposure

Abstract

New photoinitiating systems allowing an efficient cationic photopolymerization of epoxides under air using different diode lasers are presented. These new photoinitiating systems are based on various three-component photoinitiating systems i.e. violanthrone-78 (or violanthrone-79, tris(2,2′-bipyridine)ruthenium(II) dichloride, methylene blue, and iridium(III) complexes)/diphenyl iodonium salt/tris(trimethylsilyl)silane. Excellent polymerization profiles with high monomer conversions were obtained. These results allow the design of less shrinkable high speed photopolymers usable in the visible wavelength range for a variety of applications in e.g. the manufacture of optical elements. A reaction mechanism is also proposed.