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 NH 3 and water with Ar gas plasma. All plasmas in this work were non-thermal plasma with T e higher than T g , especially in N 2 and Ar/NH 3 -H 2 O plasmas, T e , T v , T r and T g were 3.3×10 4 K (ca. 2.5 eV), 7×10 3 K (ca. 0.5 eV), 1×10 3 K, and 3.2×10 2 K, respectively. In the Ar/NH 3 -H 2 O plasma, similar to the Ar/H 2 O plasma, water dissociated readily to form OH and H radicals. On the other hand, in the PTFE surface treatment with Ar/NH 3 -H 2 O plasma, the suppression of NH 3 dissociation may be caused by the increased formation of NH 3 + , 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.

Recent Advances in Surface Activation of Polytetrafluoroethylene (PTFE) by Gaseous Plasma Treatments

“…The best results in terms of the hydrophilic surface finish were reported recently by Nguyen et al [ 34 ]. The WCA dropped from the original 118° down to 4° only.…”

“…Plasma sustained by inductively coupled discharges in glass tubes was characterized by the extremely high dissociation of gaseous molecules [ 35 ]. The flux of H, N and NH radicals on the surface in the reactor adopted by Nguyen et al [ 34 ] is, therefore, considerable. Furthermore, such plasma is a tremendous source of radiation [ 36 ], so the combined effect of UV/VUV radiation causes the rapid depletion of fluorine and substitution with NH x and OH groups.…”

“…The super hydrophilic effect probably occurs in a limited range of gas concentrations. Nguyen et al reported the best results at the Ar flow of 64 sccm and NH 3 and H 2 O flow rates of 0.43 mmol/min and 0.04 mmol/min, respectively [ 34 ].…”

“…Another type of plasma used in a modification of PTFE is plasma rich in VUV radiation. Such plasma was used by Nguyen et al [ 34 ], and more recently by Lojen et al [ 38 ]. The interaction of such plasma with the PTFE surface is illustrated in Figure 8 .…”

Creation of Super-Hydrophilic Surface of Polytetrafluoroethylene Using Ammonia-Water Vapor Plasma

“…Plasma emission spectra12) : (a) NH3 plasma ; (b) Ar/ H2O plasma, Ar I represents Ar atom ; (c) Ar/NH3-H2O plasma ; (d) Ar/NH3-H2O plasma contacting with PTFE.…”