Surfacemodification of polymer films with a remote atmospheric pressure d.c. glow discharge: influence of substrate location

This study focuses on the surface treatment of polymer films (polypropylene and polyethylene terephthalate) with a remote atmospheric pressure d.c. glow discharge operating in ambient air. The set-up used can be easily upgraded to industrial dimensions and simulates in-line processing due to the rotating drum used to mount the samples on. The discharge was characterized by measuring the voltage–current curve. From this curve, three regimes can be distinguished: corona regime, glow regime and spark regime. The voltage is adjusted so that the plasma operates in the glow regime and the treatment effects are analyzed by water contact angle and XPS measurements. It is shown that the remote plasma source is capable of reducing the contact angle and making the surface of the polymers more hydrophilic. The influence of the distance of the sample to the electrodes and the power is studied. By XPS measurements, the chemical composition of the surface after treatment is determined for different operating conditions. On none of the analyzed samples, nitrogen was detected. The main effect of the treatment is the incorporation of oxygen. Angle-resolved XPS measurements show that the composition of the top atomic layers is significantly different from that of the underlying layers. The functional groups grafted by the plasma treatment were identified by the deconvolution of the C1s peak. Copyright © 2010 John Wiley & Sons, Ltd.