p-Nitronaphthylaniline in the presence of N,N-dimethylaniline as bimolecular photoinitiating system of polymerization

Photophysics, photochemical and polymerization activity of p-nitronaphthyla niline (NNA) in the presence of N,N-dimethylaniline (DMA) as coinitiator wa s analyzed to establish the influence of the initiator nature on the photos ensizated generation of free radicals derived from DMA. Steady-state (365 n m) photolysis was carried out and detailed studies of the spectroscopy of b oth reactants were accomplished. The coinitiator DMA induces the photoreduc tion of NNA with a very low photoreduction quantum yield, although the stoi chiometry of the reaction revealed that up to 570 molecules of DMA are cons umed by each NNA molecule photoreduced. The efficiency of NNA/DMA system as photoinitiator was studied following the polymerization kinetics of lauryl acrylate monomer by Differential Scanning Photo-Calorimetry. The photosens ization of DMA through the excitation energy transfer of NNA, working concu rrently to the photoreduction reaction, induces a high polymerization effic iency with a very low consumption of the initiator in a catalyzer-like way. (C) 2000 Elsevier Science S.A. All rights reserved.