Phenacylpyridinium Oxalate as a Novel Water-Soluble Photoinitiator for Free Radical Polymerization

Abstract

Phenacylpyridinium oxalate (PPOx) was synthesized by counter anion exchange reaction of phenacylpyridinium bromide (PPBr) with potassium oxalate. Radicals formed from the photolysis of PPOx in aqueous solutions were capable of initiating polymerization of hydrophilic monomers such as acrylamide (AAm), 2-hydroxyethyl methacrylate (HEMA) and N-vinyl pyrrolidone (NVP). Direct decomposition of excited phenacylpyridinium ion as well as electron transfer and cleavage reactions involving both pyridinium and oxalate ions were proposed for the initiation step.