Reaction of Deuterated Polystyrenes with Hydrogen and Deuterium Atoms

Abstract

Investigation of the electron spin resonance spectra shown by finely divided polystyrene and selectively deuterated polystyrenes, upon exposure either to hydrogen atoms or to deuterium atoms, demonstrates that the predominant reaction is the addition of a hydrogen atom to the phenyl ring, thus producing a cyclohexadienyl‐type radical. The specific rate of this reaction at room temperature is estimated to be 4×10³ liters mole^—1·sec^—1; the specific rate at which hydrogen atoms react with the cyclohexadienyl‐type radical is estimated to be 10⁶ liters mole^—1·sec^—1. The rate at which iodine vapor reacts with the cyclohexadienyl radicals is probably about the same value. Qualitatively, the results produce an insight into the mechanism of the radiolysis of polystyrene. It seems evident that although the mechanism is complex, both the evolved hydrogen and the crosslinking seen in the irradiation of polystyrene occur by means of radical precursors.