Synthesis of thioxanthone-triphenylphosphine tx-tpp as an one component initiatior and the investigation of efficiency of tx-tpp for the photopolymerization

2-(diphenylphosphino)-9H-thioxanthen-9-one) (Tiyokzantontrifenilfosfin - TX-TPP) was synthesized and characterized as a photoinitiator based on thioxanthone structure. TX-TPP was found as one component Type II photoinitiator character. Photopolymerization experiments were performed for Methyl methacrylate (MMA) as a monofunctional acrylate by using TX-TPP in Dimethylformamide (DMF) with N-Methyldiathanolamine (NMDEA) in either air or/and nitrogen atmosphere. Photoinitiated polymerization of multifunctional acrylates were also performed for Trimethylolpropanetriacrylate (TMPTA) and P-3038 ( %75 Epoxy acrylate + % 25 Tripropyleneglycoldiacrylate) with NMDEA and also for P-3038 without NMDEA by using Real Time Fourier Transform Spectroscopy (RT-FTIR).The kinetic of polymerization was investigated by Photo-DSC. UV-Curing was performed by using similar formulations which were coated on tracing paper as a 12 ? thickness and cured until no visible deformation was observed by Mini-UV-Cure by 12.9 m/min.Photodecomposition of TX-TPP were recorded for certain period of irradiation time by using of medium pressure mercury lamp. It was observed that TX-TPP consumed totally after 900 seconds irradiation time. Photophysical characteristics of TX-TPP were also investigated. The florescence excitation and emission spectrum of sample which was excited at 390 nm were taken and fluorescence quantum yield was calculated as ?=0,0012 when 9,10-Diphenylantracene was used as standard. Phosphorescence measurements were performed in ethanol at 77 0K for gaining information about triplet state of photoinitiator. Phosphorescence life time of TX-TPP was measured as 92 ms. Photoinitiation mechanism of TX-TPP was investigated and found possibly a radical mechanism involved dipole interaction between the carbonyl oxygen of the MMA and the phosphorous .Key Words: Photoinitiator, photopolymerization, UV-Curing, photophysical properties, thioxanthone