New near UV photoinitiators containing benzophenone part for photoinitiating polymerization of methyl methacrylate

In this study, a variety of new trans-diphenylethylene derivatives containing phenylketone segment was synthesized, which were used as hydrogen abstracting type photoinitiators to compose two-component photoinitiating systems for free radical photopolymerization of methyl methacrylate under near UV light irradiation. The corresponding photosensitizers free of phenylketone group were synthesized to compose three-component photoinitiating systems. The large molar extinction coefficients of the target molecules in near UV light region (350-400 nm) were observed. Near UV photoinitiating polymerization kinetics of methyl methacrylate by the target molecules was studied by photo-differential scanning calorimetry. The results suggested that the two-component photoinitiating systems produced more efficient photoinitiating polymerization of methyl methacrylate than the three-component ones. The photoinitiating mechanism of the studied photoinitiators was studied by the electron spin resonance as well as the cyclic voltammograms. The thermal stabilities of the studied photoinitators were further evaluated.