Development of Photoacid and Photobase Generators as the Key Materials for Design of Novel Photopolymers

Abstract

Novel photoacid and photobase generators for photopolymers developed in our laboratory are reviewed. Oxime sulfonates derived from 9-fluorenone and thioxanthone and imidosulfonates with thioxanthone skeleton or thianthrene moiety were developed as the i-line sensitive photoacid generators. Their photochemistry at i-line irradiation and their use in the photocrosslinking of polymers with pendant epoxy groups were investigated. The novel photosensitive polymers which are crosslinked photochemically in the presence of photoacid generators and the resulting crosslinked one can be degraded by the acids were developed. Carbamoyloximes, carbamates with imido structure, and quaternary ammonium salts were investigated as photobase generators. Copolymers with pendant carbamoyloxime moiety were proved to be very effectively crosslinked with photo-irradiation followed by baking, because amino and isocyanato groups, which were generated photochemically and thermochemically, respectively, promoted the formation of urea linkages. Thermal stability on latter two photobase generators is discussed. Copolymers with pendant acyloxime units in the block in both ends were found to be more effective crosslinkers for poly(glycidyl methacrylate) than those with random pendant groups. Novel photopolymers using photobase generators, which were photochemically crosslinked and followed by thermal degradation, were developed.