EFFECT OF MONOMER CHARACTERISTICS ON PHOTOINITIATING ACTIVITY OF CAMPORQUINONE/1,3-BENZODIOXOLE SYSTEM

Real-time infrared spectroscopy (RT-FTIR) was used to study the effect of chemical structure of oligomer, reactive diluent and the ratio of oligomer and reactive diluent on the initiating activity of camphorquinone (CQ)/1,3-benzodioxole (BDO). The results showed that, urethane dimethacrylate (UDMA) with a low viscosity was prone to chain transfer reaction and had hydrogen donating ability. In the polymerization system with high content of UDMA,UDMA could be used as a competitive hydrogen donor to interact with the exited CQ, which significantly influenced the interaction of exited CQ and BDO. Another commercial oligomer 2,2-bis[4-(2-hydroxy-3-methacryloxypropoxy) phenyl] propane (bis-GMA) with a high viscosity exhibited a high reactivity. When it combined with reactive diluent triethylene glycol dimethacrylate (TEGDMA) in the formulation, a relatively less amount of TEGDMA, i.e. 30%, could greatly reduce the viscosity of the monomer system and have little influence on the reactivity of Bis-GMA. At the same time, the Bis-GMA/TEGDMA (70/30, W/W) system with a lower viscosity could greatly improve the mobility of the free radical active species, which was beneficial to improve the initiating activity of CQ/BDO.