Nitric Oxide Radical Trapping Analysis on Vacuum-Ultraviolet Treated Polymers

Abstract

Vacuum-ultraviolet (VUV) radiation causes the dissociation of organic σ bonds such as the C−C and the C−H bonds in polyolefins. The radicals formed in this process were investigated by trapping with nitric oxide. PE, PP, and PS were irradiated in ultrahigh vacuum with the MgF2-filtered radiation of a hydrogen plasma. After an irradiation period of 1 h and an immediate radical trapping, PE, PP, and PS incorporate 1.4, 0.4, and 0.2 atom % nitrogen, respectively, measured by XPS. These nitrogen concentrations correspond to 5.4 × 1020, 1.4 × 1020, and 0.8 × 1020 spins/cm3, respectively. By the fitting of the XPS-N1s peaks, detailed information about the nitrogen functional groups and about the original radical types was obtained.