Advances in the Design of Photoinitiators, Photo-Sensitizers and Monomers for Photoinitiated Cationic Polymerization

摘要

The present article reports on recent work from this laboratory that has led to advances in several areas of the field of photoinitiated cationic polymerization. Two different classes of novel photoinitiators 5-arylthianthrenium salts and 4-hydroxyphenyl dialkylsulfonium salts have been prepared and their use in the polymerization of various monomer systems studied. Also described is the development of both monomeric and polymeric photosensitizers that may be employed to broaden the spectral sensitivity of various onium salt photoinitiators. Acceleration of rate of the ring-opening polymerization of epoxide monomers has been achieved through the use of benzyl alcohols. Further, benzyl alcohols bearing sensitizing groups were found to be especially interesting as combination accelerators-photosensitizers. Lastly, epoxy monomers having groups with easily abstractable protons display exceptional reactivity in photoinitiated ring-opening cationic polymerization. A mechanism has been proposed to explain this observation.