Photophysics and photochemistry of p-nitroaniline as photoinitiator

Steady-state (313 and 365 nm) and laser (308 and 337 nm) photolysis have been employed to carry out a structure-reactivity investigation on p-nitroaniline as photoinitiator of polymerization. Detailed studies on the spectroscopy of the molecule were accomplished. Quantum yields of p-nitroaniline photoreduction induced by a tertiary amine, 2-(N,N-diethylamino) ethanol have been determined. The dependence of the photoreduction behaviour on several factors, such as photoinitiator concentration, proportion of the aliphatic amine added to p-nitroaniline as reducing agent, nature of the coinitiator, irradiation energy, and wavelength has been studied. The analysis by gas chromatography-mass spectroscopy technique of the photolysed solutions allowed 1,4-benzenediamine to be identified as the main photoreduction product. A mechanism for the p-nitroaniline photoreduction induced by the aliphatic amine is suggested. (C) 1997 Elsevier Science S.A.