Cationic photopolymerization of alkyl glycidyl ethers

Am investigation of the photoactivated cationic ring-opening frontal polymerizations of a series of alkyl glycidyl ethers was carried out with the aid of a novel technique, optical pyrometry. With this technique, the effects of various experimental parameters, such as the photoinitiator type and concentration, as well as the effects of the monomer structure on the frontal behavior of these monomers were examined. Upon irradiation with UV light, the photopolymerizations of many alkyl glycidyl ethers displayed a prominent induction period at room temperature as the result of the formation of long-lived, relatively stable secondary oxonium ions. The input of only a small amount of thermal activation energy was required to induce the further reaction of these species with the consequent autoaccelerated exothermic ring-opening polymerization. Photoactivated frontal polymerizations were observed for both mono- and polyfunctional alkyl glycidyl ether monomers. The ability of monomers to exhibit frontal behavior was found to be related to their ability to stabilize the secondary oxonium ion intermediates through hydrogen-bonding effects. (c) 2006 Wiley Periodicals, Inc.