A known photoinitiator for a novel technology: 2-(4-methoxystyryl)-4,6-bis(trichloromethyl)-1,3,5-triazine for near UV or visible LED

Abstract

2-(4-Methoxystyryl)-4,6-bis(trichloromethyl)-1,3,5-triazine (R–Cl) appears as a versatile high-performance photoinitiator (PI) under LED exposure at 385, 395 or 405 nm (intensities in the range ∼9–140 mW cm−2). It has been used as an efficient Type I cleavable PI for the free radical photopolymerization (FRP) of (meth)acrylates under near UV or visible LED irradiation. When combined with various additives (i.e. amine, iodonium salt, or N-vinylcarbazole), the R–Cl based photoinitiating systems can exhibit an even higher efficiency than R–Cl alone. Remarkably, R–Cl alone as well as the R–Cl/additive systems lead to a photoinitiation ability for the FRP of methacrylate under air at 405 nm that is better than that of well-known commercial photoinitiators (e.g. bisacylphosphine oxide (BAPO), 2,4,6-trimethylbenzoyl-diphenyl-phosphineoxide (TPO), or 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1 (BDMB)). In addition, the R–Cl/iodonium salt/N-vinylcarbazole combination can also initiate the cationic polymerization of epoxides in the 385–405 nm range. Moreover, the photochemistry of these systems has been investigated by steady state photolysis, molecular orbital (MO) calculations, and electron spin resonance spin trapping techniques.