A Study on Performance and Mechanism of a Three-Component Photoinitiating System Based on Safranine

Since 1980s, visible light initiating systems have been highly regarded due to the overcome of UV initiating systems challenges. In this study, a new visible light three-component photoinitiating system (PIS) consisted of safranin O (SFH+), thiol derivatives and diphenyl iodonium salt was used for the free radical photopolymerization of a diacrylate monomer (SR349). Conversion and rate of polymerization of SR349 were determined by using RT-FTIR. Results showed that the new PIS could be used as an efficient PIS for free radical photopolymerization. The final conversion of photopolymerization reaction of the acrylate system was found to be more than 75%. In addition, the initiating mechanism of the three-component PIS was studied by using laser flash photolysis (LFP). It was shown that radicals were produced by a sequential reaction between photosensitizer and coinitiators. Also, photosensitizer would be reproduced by a photocyclic reaction behavior.