Reactions of hydroxyl radicals with polystyrene

The reaction of polystyrene with hydroxyl radicals, generated by the photolysis (λ > 300 nm) of H₂O₂, has been studied at 25° in dichloromethane solution, both under vacuum conditions and in presence of O₂. Spectroscopic analyses suggest the presence of phenols and hydroxymucondialdehydes (when O₂ is present) among the reaction products, indicating that OH addition occurs at the phenyl groups of the polymer. By comparison with initiated oxidation reactions under the same conditions, it is concluded that the OH radicals undergo mainly addition reactions. A mechanism has been produced to account for the products. The significance of OH addition reactions in the oxidation of polystyrene is considered, the OH radicals being produced by hydroperoxide decomposition during oxidation, and the products having been previously identified as containing mucondialdehydes.