A Simple Approach to Surface Modification Using Polytetrafluoroethylene (PTFE) with Laminar and Turbulent Flows of Micro Plasma Jets at Atmospheric Pressure

Abstract

Unlike large area plasmas, small size plasma jets could be useful in treating localized regions. For this reason, we developed a micro plasma jet having a polytetrafluoroethylene (PTFE) part exposed to the discharge inside the plasma source. As the helium gas flow rate was raised from 0.1 to 6.0 slpm, the plasma exhibited a change in characteristic from laminar to turbulent and an abrupt change of appearance at a certain flow rate (2.0–3.0 slpm). The measured rotational temperature was above 500 K under laminar flow conditions, which was a sufficiently high temperature for the pyrolysis of PTFE, and the excitation temperature of the laminar flow was higher than that of the turbulent flow. The corresponding optical emission spectra were different (CN, C2, F I, Hα dominated for laminar conditions while N 2+, OH, O I dominated for turbulent flow conditions). These different plasma characteristics were obtained by simply controlling the gas flow rate. A feasibility study of surface modification demonstrated a change of the surface wettability from hydrophobic to hydrophilic (and vice versa) depending only on the gas flow rate.

Enhancement of Surface Wettability by Intra-Helium Plasma for Liquid Core Fiber Lens

“…Sufficiently high electromagnetic energy can dissociate gas to create a chemically reactive gas composition that modifies the exposed surfaces [5]. For example, helium and argon generate free radicals on the surface, and react with adjoining radicals of molecules, increasing the surface energy and adding polar surface functions, resulting in hydrophilic surfaces [1], [6].…”

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Wettability of modified silica layers deposited on glass support activated by plasma

“…Solid surface properties can be modified by different ways such as chemical vapor deposition and plasma surface treatment [13]. The latter provides an alternative to traditional methods of surface modification by wet chemical cleaning, etching, crosslinking and functionalization [14,15] Yamamoto et al [16] investigated the influence of background gas (air, nitrogen, helium), flow rate and plasma treatment time on improvement of the hydrophilic and hydrophobic properties of glass with atmospheric pressure non-thermal plasma.…”

Changes in surface properties of polymethylmethacrylate (PMMA) treated with air plasma

“…The hydrophilic-hydrophobic properties of solids can be modified in several different ways, among others plasma surface treatment has become a very popular means [1][2][3][4][5]. This technique provides an alternative to traditional methods of surface modification like wet chemical cleaning, etching, cross-linking and functionalization.…”