Poly(propylene oxide)-thioxanthone as one-component Type II polymeric photoinitiator for free radical polymerization with low migration behavior

A novel kind of low migration one-component Type II photoinitiators was synthesized by Schiff base reaction of thioxanthone aldehyde and amine functional poly(propylene oxide) (PPO) precursors with two different molecular weights. The final initiators (TX-PPO) were characterized in detail by spectral analysis and DFT theoretical calculations. The molecular weight of the PPO directly effects the solubility of the initiator in monomers. The one-component photo initiating nature of the initiators was demonstrated by photobleaching and photo polymerization of several vinyl monomers in the absence of a hydrogen donor such as triethylamine. Leaching studies on the photocured polymer films show only negligible migration of the photoinitiator.