An investigation of the surface properties and curing behavior of photocurable cationic films photosensitized by anthracene

We investigated differences in the curing behavior of cationic photopolymerizations photosensitized by anthracene by preparing various epoxy/vinyl-ether-based formulation systems with and without anthracene photosensitizer. Cationic photopolymerizations of formulations with different ratios of diglycidyl ether of bisphenol A epoxide (DGEBA), 1,4-cyclohexane dimethanol divinyl ether (CHVE), and anthracene were investigated using differential photocalorimetry (photo-DSC) and Fourier-transform infrared spectroscopy with attenuated total internal reflection (FTIR-ATR). In photo-DSC experiments, the formulations containing more than 5% (by weight) anthracene exhibited a two-stage exothermic reaction. As the concentration of anthracene photosensitizer was increased, the first exotherm. decreased and the second one increased. Photo-DSC and real-time infrared spectroscopy analyses showed that the reaction rate increased as the anthracene photosensitizer concentration was increased. Depth profile analyses using FTIR-ATR spectroscopy showed that the films containing more than 0.5% anthracene exhibited significantly improved surface properties and more thorough curing for film thicknesses,up to 100 mum. (C) 2002 Elsevier Science Ltd. All rights reserved.