Simultaneous Photoinduced Color Formation and Polymerization: The Formation ofHighly Colored Thin Films from Colorless Precursors Due to Formation of Triarylmethane Cations by Acid Generating Decomposition of Iodonium Salts

摘要

Highly colored thin films were prepared by irradiating transparent resinsconsisting of the iodonium salt 4-(octyloxyphenyl)phenyliodonium hexafluoroantimonate (OPPI, 1) and a dye precursor such as crystal violet lactone (CVL, 2) dissolved in an acrylate epoxide mixture. Color formation is explained in that dye precursors, such as CVL, form highly colored species in acidic media and iodonium salts generate photoacid upon irradiation. It has been demonstrated that CVL and OPPI is an efficient photoinitiator for radical polymerizations, while OPPI alone is an efficient photoinitiator for cationic polymerizations. The main advantage of our approach, by which films of different colors can be made, is that highly colored films can be cured at rates comparable with those of noncolored films.