Influences of Additive Gas on the Improvement of Hydrophilicity of Polymer Surface by a Cold Atmospheric Pressure Ar Plasma Jet

Abstract

In this paper, active species in a cold atmospheric pressure RF capacitive Ar plasma jet were characterized using optical emission spectrometry (OES). OES revealed that excited Ar atoms (4p-4s transitions) were predominant in the plasma jet, and no ions were detected in the plasma afterglow even after the addition of N₂ or O₂. It was expected that this Ar plasma jet was quite suitable for polymer surface treatment with no serious surface decomposition. As an application to the Ar plasma jet, high-density polyethylene (HDPE) surface was treated with Ar, Ar/O₂ and Ar/N₂ plasmas, respectively. Influences of additive gas on the improvement of the hydrophilicity of polymer surface were investigated in details. It was found that an enhancement of the hydrophilicity of HDPE surface was observed when N₂ or O₂ as an additive gas was added into the Ar plasma.