Abstract: Triarylsulfonium Salts and diaryiodonium salts are photoinitiator for cationic polymerization as well as photo-acid generator. However, they exhibit low absorptivity above 300 nm, which limits the efficiency of light use for common UV sources. In order to overcome this limitation, a number of novel iodonium salts and sulfonium salts were prepared and their photoactivity for cationic polymerization were investigated by gel time studies. The results indicated that 2-phenylsulfur-methyl, 2’,4’-dimethyl diphenyl iodonium salts and 9-anthryl-propyl, diphenyl sulfonium salts, which possess built-in sensitizer, show very high photoactivity. An intramolecular electron transfer mechanism has been proposed to explain this result. Thus, the anthryl group(An) is an electron donor and a built-in sensitizer group on the molecule of 9-anthryl-propyl, diphenyl sulfonium salts, and the photoreaction can be shown as following: .

Key words: onium salt, photoinitiator, photosensitization, electron transfer, synthesis