A low migration phosphine to overcome the oxygen inhibition in new high performance photoinitiating systems for photocurable dental type resins

The objective of this work was to propose a novel low migration additive (i.e. a phosphine) to overcome the oxygen inhibition in a camphorquinone (CQ) base photoinitiating system for the polymerization of methacrylates (e.g. a bisphenol A-glycidyl methacrylate (Bis-GMA)/triethyleneglycol dimethacrylate (TEGDMA) blend (70%/30% w/w)) upon exposure to a commercial blue light emitting diode centred at 477 nm. CQ/amine/phosphine derivative or CQ/amine/iodonium salt/phosphine derivative combinations were studied. Real-time Fourier transform IR and photo-DSC experiments were used to monitor the polymerization profiles. Remarkably, it was found that the addition of the new phosphine derivative to CQ/amine or CQ/amine/iodonium salt noticeably improved the rate of polymerization and the final conversion in air. A low migration was found for this additive as shown by HPLC experiments in agreementwith a copolymerizable behaviour. No additional yellowing of the film was observed. Electron spin resonance spectrometry was used to detect the produced radicals. The overall chemical mechanisms are investigated and discussed. (C) 2016 Society of Chemical Industry