Photochemical and photopolymerization study of 2,6-dihalogen derivatives of p-nitroaniline in the presence of N,N-dimethylaniline as a bimolecular photoinitiator system

Steady-state photolysis at 365 nm has been employed to carry out a structure-reactivity investigation of the 2,6-dihalogen derivatives of p-nitroaniline (pNA). Detailed studies of the spectroscopy of these molecules were accomplished. Photoreduction behavior of the 2,6-dihalogen derivatives of p-nitroaniline in the presence of N,N-dimethylaniline (DMA) has been analyzed. The efficiency of these compounds as photoinitiators was studied by following the polymerization kinetics of the lauryl acrylate (LA) monomer by differential scanning photo-calorimetry (Photo-DSC) under aerobic and anaerobic conditions. Using size exclusion chromatography (SEC) analysis of the polymers their number-average molecular weights, the number-average degree of polymerization, and the length of the kinetic chain were determined and information on the nature of the end-chain groups and the chain-transfer behavior of these photoinitiators systems were obtained. The polymerization activity of the 2,6-dihalogen derivatives of pNA proved to be higher than those obtained with conventional aromatic ketone photoinitiators.