title: A novel photoinitiating system producing germyl radicals for the polymerization of representative methacrylate resins: Camphorquinone/R3GeH/iodonium salt.
abstract: The aim of our study is to find an amine free photoinitiating system (PIS) for the polymerization of representative dental methacrylate resins. A photoinitiating system (PIS) based on camphorquinone (CQ)/triphenylgermanium hydride/diphenyl iodonium hexafluorophosphate is proposed and compared to the conventional CQ/amine couple. The polymerization monitoring of thin (∼20μm) and thick (1.4mm) samples of a bisphenol A-glycidyl methacrylate (Bis-GMA)/triethyleneglycol dimethacrylate (TEGDMA) blend (70%/30% w/w) and of a urethane dimethacrylate (UDMA) upon exposure to a commercial blue LED centered at 477nm under air or in laminate is described. Finally, the impact of the photoinitiating system composition on the final polymer color is evaluated in detail.
  
  
  
  FTIR and DSC experiments are used to record the photopolymerization profiles. ESR spectrometry and steady state photolysis are used to detect the produced radicals. Color measurements are carried out to determine the key parameters in the bleaching of the different dental formulations.
  
  
  
  The efficiency of the newly proposed PISs for the photopolymerization of BisGMA/TEGDMA and UDMA for thin (20μm) or for thick (1.4mm) samples upon exposure to a dental blue LED under air is excellent. It is noticeably higher than that of the CQ/amine reference couple. Excellent bleaching properties are also observed under irradiation in presence of the new PISs. A good correlation is found between the sample bleaching and the amount of Ph3GeH in the formulation. The excited state processes could be established. The overall chemical mechanisms for the initiation step were also clarified.
authors: Institut de Science des Matériaux de Mulhouse IS2M, UMR CNRS 7361, UHA, 15, Rue Jean Starcky, 68057 Mulhouse Cedex, France.
authors: Mariem
authors: M
authors: Bouzrati-Zerelli
authors: DENTSPLY DeTrey, De-Trey-Straße 1, Konstanz, Germany.
authors: Maximilian
authors: M
authors: Maier
authors: Institut de Science des Matériaux de Mulhouse IS2M, UMR CNRS 7361, UHA, 15, Rue Jean Starcky, 68057 Mulhouse Cedex, France.
authors: Celine
authors: C
authors: Dietlin
authors: Institut de Science des Matériaux de Mulhouse IS2M, UMR CNRS 7361, UHA, 15, Rue Jean Starcky, 68057 Mulhouse Cedex, France.
authors: Morlet-Savary
authors: MS
authors: Fabrice
authors: Institut de Science des Matériaux de Mulhouse IS2M, UMR CNRS 7361, UHA, 15, Rue Jean Starcky, 68057 Mulhouse Cedex, France.
authors: Jean Pierre
authors: JP
authors: Fouassier
authors: DENTSPLY DeTrey, De-Trey-Straße 1, Konstanz, Germany. Electronic address: joachim.klee@dentsply.com.
authors: Joachim E
authors: JE
authors: Klee
authors: Institut de Science des Matériaux de Mulhouse IS2M, UMR CNRS 7361, UHA, 15, Rue Jean Starcky, 68057 Mulhouse Cedex, France. Electronic address: jacques.lalevee@uha.fr.
authors: Jacques
authors: J
authors: Lalevée
mesh_terms: D017438:Bisphenol A-Glycidyl Methacrylate; D002164:Camphor / Q000031:analogs & derivatives*; D003188:Composite Resins; D008422:Materials Testing; D008689:Methacrylates; D058105:Polymerization
chemical_list: D003188:Composite Resins; D008689:Methacrylates; D017438:Bisphenol A-Glycidyl Methacrylate; D002164:Camphor; C553149:camphorquinone
keywords: Camphorquinone; Dental composites; Germyl radicals; Methacrylates; Photoinitiator; Radical photopolymerization