Catalyst-Free Aerobic Photodegradation of Polystyrene in Chlorinated Solvents

Aerobic photochemical degradation of commercially available polystyrenes was successfully carried out in chlorinated solvents. Solvents, such as dichloromethane, 1,2,4-trichlorobenzene, and chloroform, were used as both the reaction medium and a source of halogen radicals under UV-light irradiation. The degradation kinetics in the absence of a photocatalyst was investigated. This approach achieved efficient degradation at room temperature, breaking down high molar mass polystyrenes into oligomers (< 1 kDa) while generating valuable small-molecule products such as benzoic acid. The effects of solvent, concentration, molecular weight, and light source on degradation kinetics were investigated. The process predominantly yielded benzoic acid under an O 2 atmosphere, whereas under open-air conditions, it yielded a mixture of oxidized oligomeric products.