ESR STUDY ON THE NATURE OF OXYGEN PLASMA-INDUCED SURFACE RADICALS OF TEFLON AND CORRESPONDING PEROXY RADICAL REACTIVITY

Oxygen plasma irradiation on powdered Teflon produces four kinds of radicals: midchain radicals (1), endchain radicals (2), immobilized dangling-bond sites (DBS, 3) and their corresponding peroxy radicals. The ESR spectral analyses with the aid of computer simulations indicated that each of the component radicals was essentially identical with that obtained by argon plasma irradiation. The effect of oxygen plasma irradiation on the radical formation, however, was much lower than that of argon plasma irradiation. It was also found that the ratio of DBS formation to total radical formation by oxygen plasma irradiation is to such a compatible extent as that by argon plasma irradiation. This fact is consistent with the rate of Teflon degradation induced by oxygen plasma irradiation on its comparison with those by argon plasma irradiation; the increase in such a rate was much lower than those of other hydrocarbon polymers. This specificity has been ascribed to a lower efficiency for the unsaturated-bond formation in the polymer main chain due to a larger dissociation energy of a C-F bond.