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

Photophysics, photochemical and polymerization activity of p-nitronaphthylaniline (NNA) in the presence of N,N-dimethylaniline (DMA) as coinitiator was analyzed to establish the influence of the initiator nature on the photosensizated generation of free radicals derived from DMA. Steady-state (365 nm) photolysis was carried out and detailed studies of the spectroscopy of both reactants were accomplished. The coinitiator DMA induces the photoreduction of NNA with a very low photoreduction quantum yield, although the stoichiometry of the reaction revealed that up to 570 molecules of DMA are consumed 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 photosensization of DMA through the excitation energy transfer of NNA, working concurrently to the photoreduction reaction, induces a high polymerization efficiency with a very low consumption of the initiator in a catalyzer-like way. (C) 2000 Elsevier Science S.A. All rights reserved.