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 str ucture-reactivity investigation of the 2,6-dihalogen derivatives of p- nitroaniline (pNA). Detailed studies of the spectroscopy of these mole cules 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 photoinit iators was studied by following the polymerization kinetics of the lau ryl acrylate (LA) monomer by differential scanning photo-calorimetry ( Photo-DSC) under aerobic and anaerobic conditions. Using size exclusio n chromatography (SEC) analysis of the polymers their number-average m olecular weights, the number-average degree of polymerization, and the length of the kinetic chain were determined and information on the na ture 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 ob tained with conventional aromatic ketone photoinitiators.