This article describes the development of optical pyrometry (OP) as a new analytical technique for the continuous monitoring of the progress of both free-radical and cationic photopolymerizations. The method is rapid, reproducible, and very easy to implement. A temperature profile of a photopolymerization can be obtained. Preliminary studies have shown that the temperatures of some polymerizing monomers can easily reach temperatures in excess of 250°C. The effects of the mass and reactivity of the monomer, light intensity, structures, and concentrations of the photoinitiators and monomers as well as the presence or absence of oxygen on various free-radical and cationic photopolymerizations were examined with this method. Coupling of real-time infrared spectroscopy with OP provides a convenient method for simultaneously monitoring both the chemical conversion and the temperature of a photopolymerization. This combined technique affords new insights into the effects of temperature-induced autoacceleration on the course of photopolymerizations.

The photoinitiated cationic ring-opening polymerizations of certain epoxides and 3,3-disubstituted oxetanes display the characteristics of frontal polymerizations. When irradiated with UV light, these monomers display a marked induction period, during which little conversion of the monomer to the polymer takes place. The local application of heat to an irradiated monomer sample results in polymerization that occurs as a front propagating rapidly throughout the entire reaction mass. For the characterization of these frontal polymerizations, the use of a new monitoring technique, employing optical pyrometry, has been instituted. This method provides a simple, rapid means of following these fast polymerizations and quantitatively determining their frontal velocities.

Photoactivated cationic ring‐opening polymerizations of certain oxirane and oxetane monomers take place in a frontal manner. The study of the frontal behavior of those monomers was conducted using a new analytical technique involving optical pyrometry that provides insight into the mechanism of these polymerizations.

Studies of the photoinitiated cationic ringopening polymerizations of epoxide and oxetane monomers were conducted using optical pyrometry. Using this technique, the temperature of these photopolymerizations was monitored as a function of time. The effects of photoinitiator type and monomer structure on the rates of photopolymerization were investigated. Optical pyrometry was also used to investigate the acceleration of the photopolymerizations of various epoxide and oxetane monomers. Certain mixtures of monomers displayed synergistic effects that markedly increased their overall rates of polymerizations. In all cases in which acceleration of polymerization rate was noted, it could be attributed to an increase in the speed of ring opening of the initially formed protonated cyclic ether. The effects of relative humidity on the rate of cationic ringopening photopolymerizations of cyclic ether monomers were also investigated.

This article describes the development of a novel rapid one-step cationic suspension photopolymerization method for the synthesis of epoxy-functional polymeric microspheres ranging in size from 50 nm to 100 μm. Multifunctional silicon-containing epoxy monomers and oligomers were photopolymerized to produce microspheres in both in aqueous and nonaqueous suspensions using a variety of cationic photoinitiators. Various solvents with controlled polarities were employed to produce macroporous particles. The effects of a variety of experimental and compositional variables on the particle diameter, size distribution, and epoxy content of the microspheres were examined. Among the parameters that were evaluated were the initiator composition and concentration, agitation method, UV irradiation time, viscosities of both the monomer and suspending medium, and type of porogen used. Following synthesis, the microspheres were characterized by SEM microscopy and by titration to determine the epoxy-functional group content. Microspheres that were subjected to pyrolysis at 700 °C retained their macrostructure despite undergoing a 60% weight loss.