Activation of the Internal Surfaces of Polymer Tubes with Argon Plasma Through Hollow Cathode Effect
4 affiliations
- 1Department of Biomedical Engineering, National Yang Ming Chiao Tung University, Taipei 300093, Taiwan
- 2Center for Plasma and Thin Film Technologies, Ming Chi University of Technology, New Taipei City 243303, Taiwan
- 3Department of Materials Science and Engineering, University of California, Riverside, CA 92521, USA
- 4Plasma Technologies, Central European Institute of Technology—CEITEC, Brno University of Technology, Purkyňova 123, 61200 Brno, Czech Republic
Abstract
The focus of this study is on generating hollow cathode discharge (HCD) plasma inside three types of polymer tubes, resulting in the activation of the tubes’ inner surfaces. To achieve this goal, both theoretical calculations and experiments were carried out to prove that the adopted methodology was feasible. By applying optical emission spectroscopy, with line ratio and modified Boltzmann’s plot methods, the plasma sheath could be estimated and applied to the prediction of HCD generation. To verify whether HCD prevails in the tube, the various power inputs (70~260 W), tube diameters (3~7 mm), and working pressure (0.1 and 0.4 torr) were selected. Accordingly, it was confirmed that the tube diameter must be greater than twice the plasma sheath in order to form HCD, which would then activate the surface. Ar gas was used with a capacitive-coupled RF plasma system. PET, PU, and PTFE tubes were used in this study. The tubes’ inner surfaces were characterized with XPS and water-contact-angle (WCA) analysis. The results also show that once HCD is generated inside the tubes, these tubes’ inner surfaces could become hydrophilic, and the values of WCA might decrease by 40°, 45°, and 70° respectively for PET, PU, and PTFE, due to the combined effects of the enhanced ion bombardment and radical oxidation. XPS studies show that, for PET and PU, C-O and, particularly, C=O bonds increase significantly. For PTFE, the C-F bonds decrease, while carbon–oxygen bonds increase. Overall, the surface activation is thought to be enhanced by ion bombardment attributable eventually to the hollow cathode effect (HCE).
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BibTeX
@article{hsieh2026activation,
title = {{Activation of the Internal Surfaces of Polymer Tubes with Argon Plasma Through Hollow Cathode Effect}},
author = {Jang-Hsing Hsieh and Jyh Wei Lee and Chuan Li and Stephen Hsieh and Shin Yo Shen and Nima Bolouki},
journal = {Polymers},
year = {2026},
month = oct,
doi = {10.3390/polym18192416},
url = {https://europepmc.org/article/PMC/PMC13666709},
note = {CC BY},
}
RIS
TY - JOUR
TI - Activation of the Internal Surfaces of Polymer Tubes with Argon Plasma Through Hollow Cathode Effect
AU - Jang-Hsing Hsieh
AU - Jyh Wei Lee
AU - Chuan Li
AU - Stephen Hsieh
AU - Shin Yo Shen
AU - Nima Bolouki
PY - 2026
DA - 2026/10/01
JO - Polymers
DO - 10.3390/polym18192416
UR - https://europepmc.org/article/PMC/PMC13666709
AB - The focus of this study is on generating hollow cathode discharge (HCD) plasma inside three types of polymer tubes, resulting in the activation of the tubes’ inner surfaces. To achieve this goal, both theoretical calculations and experiments were carried out to prove that the adopted methodology was feasible. By applying optical emission spectroscopy, with line ratio and modified Boltzmann’s plot methods, the plasma sheath could be estimated and applied to the prediction of HCD generation. To verify whether HCD prevails in the tube, the various power inputs (70~260 W), tube diameters (3~7 mm), and working pressure (0.1 and 0.4 torr) were selected. Accordingly, it was confirmed that the tube diameter must be greater than twice the plasma sheath in order to form HCD, which would then activate the surface. Ar gas was used with a capacitive-coupled RF plasma system. PET, PU, and PTFE tubes were used in this study. The tubes’ inner surfaces were characterized with XPS and water-contact-angle (WCA) analysis. The results also show that once HCD is generated inside the tubes, these tubes’ inner surfaces could become hydrophilic, and the values of WCA might decrease by 40°, 45°, and 70° respectively for PET, PU, and PTFE, due to the combined effects of the enhanced ion bombardment and radical oxidation. XPS studies show that, for PET and PU, C-O and, particularly, C=O bonds increase significantly. For PTFE, the C-F bonds decrease, while carbon–oxygen bonds increase. Overall, the surface activation is thought to be enhanced by ion bombardment attributable eventually to the hollow cathode effect (HCE).
SN - 2073-4360
ER -