An investigation of the photoactivated cationic ring-opening frontal polymerizations of a series of alkyl glycidyl ethers has been carried out with the aid of a novel technique, optical pyrometry. With this technique, the effects of the monomer structure on the frontal behavior of these monomers have been examined. Upon irradiation with UV light, the photopolymerizations of many alkyl glycidyl ethers display a prolonged 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 is required to induce the further reaction of these species with a consequent autoaccelerated exothermic ring-opening polymerization. Photoactivated frontal polymerizations have been observed for both mono- and polyfunctional alkyl glycidyl ether monomers. The ability of monomers to exhibit frontal behavior has been found to be related to their ability to stabilize the secondary oxonium ion intermediates through multiple hydrogen-bonding effects to the ether groups present in the molecule. (c) 2006 Wiley Periodicals, Inc.