Photodepolymerization of poly(methyl methacrylate) nanolayer adsorbed on Silochrome

Photodepolymerization of PMMA adsorbed on Silochrome as a 1.5-2-nm-thick la yer under 240-260-nm UV irradiation was investigated in the temperature ran ge 35-180 degreesC. A linear dependence of the initial depolymerization rat e on the incident light intensity was established. It is suggested that dep olymerization proceeds in the kinetic mode (i.e., the reaction rate is inde pendent of the monomer transport from the sample) over the entire temperatu re range studied. The proposed kinetic scheme of the process consists of th e following stages: photoinitiation via the main chain scission, depolymeri zation per se, linear termination of kinetic chains due to release of low-m olecular-mass terminal radicals into the gas phase, as well as chain transf er to polymer involving only a part of degrading macroradicals.