A spectroscopic study on argon-ammonia water gaseous plasma super-hydrophilizing polytetrafluoroethylene

Abstract

In this study, optical emission spectroscopy was used to investigate the advantages of using NH3 and water with Ar gas plasma. All plasmas in this work were non-thermal plasma with Te higher than Tg, especially in N2 and Ar/NH3-H2O plasmas, Te, Tv, Tr and Tg were 3.3×104 K (ca. 2.5 eV), 7×103 K (ca. 0.5 eV), 1×103 K, and 3.2×102 K, respectively. In the Ar/NH3-H2O plasma, similar to the Ar/H2O plasma, water dissociated readily to form OH and H radicals. On the other hand, in the PTFE surface treatment with Ar/NH3-H2O plasma, the suppression of NH3 dissociation may be caused by the increased formation of NH3+, which may be a key species in promoting defluorination. Simultaneously, the higher OH radical concentration may increase more the number of polar groups bound to the polymer surface to decrease the WCA and to make PTFE surface super hydrophilic.