• Ribitsch, Volker
• Tušek, Lidija
• Stana Kleinschek, Karin

Abstract

<p>Plasmas are widely used to modify surface properties of various materials, including textiles. Additional or new groups are introduced to the surfaces, or the surfaces are coated with thin polymer films or special plasma cleaning of surfaces is carried out. This work deals with low pressure NH₃ plasma treatment of PA 6 foils and the evaluation of surface modification as a function of treatment time (7 to 540 s). The introduced functionalities were observed by contact angle measurements (assessment of wettability), streaming potential measurements (surface charge), XPS analysis (nature of introduced functionalities), and AFM (surface topography). The results show that achieved modifications depend on treatment time. NH₃ plasma improves wettability of PA 6 reducing the contact angles. The introduction of N-containing groups is increasing with longer treatment time. The nitrogen content on the foil«s surface is increased and the isoelectric point (IEP) is shifted toward higher pH values. The biggest shift of IEP was found when the treatment time was 20 s (from pH of 4,2 toward pH of 6,2). With longer treatment time, the negative plasma effect of surface destruction prevails over the positive effect of the introduction of functional groups. The nitrogen content, therefore, is reduced, contact angles are increased and IEP is shifted toward pH of 5,6 (treatment time of 180 s). AFM images of non-treated and treated samples show that plasma treatment causes loose debris on the surface, which become more numerous and larger with longer treatment time. The mean roughness is increased from 4 nm (non-treated sample) to 13,6 nm (treatment time of 540 s).</p>

Topics

• impedance spectroscopy
• surface
• polymer
• x-ray photoelectron spectroscopy
• atomic force microscopy
• Nitrogen
• pH value