Spectroscopic study on the photo-degradation and photo-oxidation of irradiated poly (4-phenyl styrene) in various solvents

Abstract

Abstract The photodegradation of pure and blended poly (4-phenylstyrene) was investigated as function of different irradiation times and in solvents of different polarities. Changing the dielectric constant of used solvent (7.5–38), was found to affect the stability of the Irradiated polymer solutions at 288 nm, using dichloromethane, dichloroethane, tetrahydrofuran and dimethyl formamide. This study was investigated with absorption, fluorescence and FT-IR spectroscopic methods at room temperature and in presence of oxygen. Irradiated polymer solutions showed a noticeable decrease in the absorption intensity and change in the structure of excimeric fluorescence band. These changes are due to the formation of photo-products as a result of photo-degradation and photo-oxidation processes. Added Dimethyl terephthalate, Diethyl terephthalate, dioctyl terephthalate, dibutyl phthalate and Dioctyl phthalate plasticizers to the polymer solutions, caused a noticeable enhance in the intensity of the fluorescence main band, using dichloromethane, dichloroethane and tetrahydrofuran solvents, while it showed an increase in case of using dimethyl formamide solvent. The polymer fluorescence main band showed a considerable decrease in its intensity by the decrease in the polarity of the used solvents, and to accelerate degradation process. The suggested mechanism accounts the effect of the increase in exposure time on photodegradation and photo-oxidation processes in polymeric chains.