Frontal modes of propagation of photochemical reactions in glassy polymers

Peculiarities of the frontal propagation of photochemical processes in glas sy polymers are demonstrated with an example of 9,10-diphenylanthracene oxi dation in PMMA. It is reliably established that the effective width is grea ter, and the propagation rate is lower than in media with a high molecular mobility. The region of high reacted fractions in the photochemical front e xpands particularly conspicuously. When the process takes place in a sample activated thermally at regular intervals, the above peculiarities disappea r, and the shape of the front and the velocity of its propagation are descr ibed by a simple model for a system with complete bleaching of the medium. Since peculiarities of formation and propagation of the front are the more pronounced the more distinct the kinetics of reagent consumption in optical ly thin samples, it is safe to assume that these peculiarities originated f rom the kinetic dissimilarity of reacting species in solid polymers.