PHOTOCHEMISTRY AND PHOTOPOLYMERIZATION ACTIVITY OF P-NITROANILINE IN THE PRESENCE OF N,N-DIMETHYLANILINE AS A BIMOLECULAR PHOTOINITIATOR SYSTEM

The photoreduction behavior of p-nitroaniline (pNA) in the presence of N,N-dimethylaniline (DMA) induced by both steady-state (365 nm) and l aser (337 nm) irradiation has been analyzed. The stoichiometry of the photoreduction reaction revealed that several amino radicals derived f rom DMA were generated by each photoreduced pNA molecule. The polymeri zation kinetics of the lauryl acrylate monomer (LA) photoinitiated by the pNA/DMA system has been studied by differential scanning photocalo rimetry (Photo-DSC). The rate of polymerization was found to be propor tional to the square root of both the incident light and the coinitiat or DMA concentration. The order of the polymerization reaction with re spect to monomer and initiator concentration was determined, as well a s the polymerization behavior under aerobic conditions. The polymeriza tion efficiency of this photoinitiated system was much higher than tha t obtained with conventional aromatic ketone photoinitiators. (C) 1997 John Wiley & Sons, Inc.