Development of Pyrene Photosensitizers for Cationic Photopolymerizations

This article describes the preparation of monomeric and oligomeric derivatives of pyrene and their use as electron-transfer photosensitizers for onium-salt-induced cationic photopolymerizations. The synthetic methods that were employed involved simple, straightforward, and high-yield routes to these derivatives. Using Fourier transform real-time infrared spectroscopy, the photoinduced polymerizations of several model epoxide monomers and a vinyl ether monomer were examined in the presence and absence of the photosensitizers. It was observed that in all cases the pyrene derivatives markedly accelerated the rates of the UV-irradiation-induced photopolymerizations. Use of the pyrene derivatives also provided sensitivity to visible light so that photopolymerizations could be carried out in a short time by exposure to direct sunlight. The pyrene compounds investigated in this study are potentially attractive photosensitizers that may find use in many practical photocuring applications.