Radical generation from photoinitiator (IC 2959) decomposition and radical addition to acrylate. A laser photolysis Fourier transform electron paramagnetic resonance study

Abstract

The decomposition of the photoinitiator 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methylpropan-1-one (trade name IC 2959) was studied using time-resolved laser photolysis Fourier transform electron paramagnetic resonance. The emissive CIDEP polarization of both benzoyl and 2-hydroxy-2-propyl radicals indicates the triplet state of IC 2959 as the radical precursor. By adding n-butyl acrylate it was shown that the addition of 2-hydroxy-2-propyl radicals to the acrylate double bond is two orders of magnitude faster than that of benzoyl radicals.