Diphenyldiselenide as novel non-salt photoinitiator for photosensitized cationic polymerization of N-vinyl carbazole

Photoinitiated cationic polymerization of N-vinyl carbazole (NVC) with diphenyldiselenide (DPDS) as an initiator and aromatic nitriles such as dicyano-naphthalene (DCN) and dicyanoanthracene (DCA) as sensitizer was studied at lambda > 290 nm in CH2Cl2 solvent using single electron transfer (SET) reactions in this investigation. Aromatic nitriles were found to be effective photosensitizer in initiating polymerization at wavelength lambda > 290 nm where DPDS (lambda(max) = 246 nm) do not absorb. However, the DPDS works well as an initiator with both DCN and DCA. An initiation mechanism is also proposed that involves the formation of selenium radical cation as actual initiating species. Upon photoirradiation, these radical cations are formed by single electron transfer between the excited singlet state sensitizer and the ground state of DPDS.