Surface Modification of Polytetrafluoroethylene
by Atmospheric Pressure Plasma ofDielectric Barrier Discharge using
Argon/Ammonia-Water Vapor Mixture Gas
H. Yajima*, S. W. Fitriani**, I. Serizawa*, and A. Hatta**, **** ORC Manufacturing, Co., Ltd., 4896 Tamagawa, Chino, Nagano, 391-0011, Japan,** Dept. Ele. & Photo. Eng., *** Center for Nanotechnology, Research Institute, Kochi University of Technology, 185 Miyanokuchi,
Tosayamada, Kami, Kochi, 782-8502, Japan
Abstract-- Surface modification of polytetrafluoroethylene (PTFE) by atmospheric pressure plasma treatment using a gas mixtureof argon and ammonia-water vapor was examined. As a simple method of supplying ammonia, argon gas was bubbled into ammonia
water with variation of the concentration from 0% to 20%. A specimen of PTFE sheet was irradiated with the plasma generated bydielectric barrier discharge. After the plasma treatment for 10 seconds, hydrophilic surface of around 57˚ static water contact angle
was achieved at the concentration more than 10% while the original PTFE surface showed hydrophobic around 110˚.

I. INTRODUCTION

III. RESULTS AND DISCUSSION

Variousmethods
forhydrophilization
ofpolytetrafluoroethylene (PTFE) surface have been known.
In those methods, the chemical treatments have a hugeenvironmental impact, the UV irradiation and the lowpressure plasma treatments have small processing speed,
and the electron beam and ion beam irradiation require
expensive equipment. The atmospheric pressure plasma
treatment has been expected to provide rapid andinexpensive methods.
We have reported surface modification of PTFE byatmospheric pressure plasma using argon gas with liquid
vapor of water, alcohol, acetone and water-ethanol [1,2].
In this study, a novel gas mixture of argon withammonia-water vapor is examined using the same
experimental configuration as previous.

Fig. 2 shows the static water contact angle (WCA) of
PTFE treated by the plasma for 10 seconds as a functionof the ammonia concentration. By addition of theammonia-water vapor in argon, the WCA decreased
obviously as compared to pure argon. The WCA slightly
decreased from 67˚ to 57˚ with increasing theconcentration from 0 to 10%. The amount of hydrogen in
the plasma which contributes to the surface modificationof PTFE, could have been increased [2]. There was no
significant difference in the WCA at the ammonia-water
concentration more than 10%.

Fig. 1 shows experimental setup for plasma treatment
of PTFE using argon gas with ammonia-water vapor.
Argon gas was bubbled into the ammonia-water which
concentration varied from 0% to 20%, and the gas
mixture was introduced into the discharge cell.
Atmospheric-pressure plasma was generated by dielectricbarrier discharge using a pair of copper electrodes placedon the external surface of parallel glass plates. The
sample of PTFE sheet was placed on the lower glass platewith leaving 1 mm discharge gap.
500 sccm
Flow meterArAmmoniawater

10 kVp-p 25 kHz

Copper electrode(10×10 mm)

40 mm

2 mm

PTFE sheet(30×30 mm
t = 1 mm)

Glass plate(t = 0.3 mm)

Water bath, T = 20˚Fig. 1. Experimental setup for atmospheric pressure plasma treatment
of PTFE using argon gas with ammonia-water vapor.

Water contact angle (˚)

II. MATERIAL AND METHODS120

WCA of untreated PTFE = 110˚10080

WCA of Ar plasma treated PTFE = 77˚6040200Standard error
N=505101520Ammonia concentration (wt%)

25Fig. 2. WCA of the PTFE after 10 seconds treatment by argon/ammonia-water vapor plasma as a function of ammonia concentration.

IV. CONCLUSIONSThe PTFE surface was treated by atmospheric pressureplasma using an argon/ammonia-water vapor mixture gas.
The hydrophilization effect was enhanced by introducing
ammonia-water vapor into argon as discharge gas andwas further improved with increasing ammonia
concentration in water until 10%.
REFERENCES[1] H. Yajima et al., Proc. of 16th Int. Conf. on Plasma
Surface Engineering (PSE 2018), Garmisch-Partenkirchen(Germany), Sept. 2018, p.312.
[2] S. W. Fitriani et al., Mater. Chem. Phys., vol. 282, 125974,
March 2022.