Poly‐ether‐ether‐ketone (PEEK) surfaces have been treated by atmospheric pressure plasma to increase their surface free energies − and hence, their adhesion potential towards metallic coatings as assessed by pull‐off test. Firstly, we show that adsorbed water on the polymer surface prior to plasma treatment acts as a shielding barrier against activation of the surface. This shielding effect is annealed by either a second plasma scan or by drying the surface before activation. Secondly, the relative humidity rate seems to be the main aging parameter on plasma‐treated surfaces. Our study reveals that high values of surface energies, and thus adhesion potential, can be assured and maintained for months by storing the material in a dry atmosphere before and after treatment.
The effects of the surface modification of poly(ether ether ketone) (PEEK) by plasma treatment have been characterized by X-ray Photoelectron Spectroscopy and wettability 2 measurement, whilethe adhesion of metallic thin films grown by PVD has been assessed by the pull-off test. To investigate the role of the modified surface chemistry on the practical adhesion stress of aluminium thin films, two different plasma technologies were considered: (i) atmospheric pressure plasma and (ii) low pressure microwave plasma. Though on different scales, both of these plasmas under oxidative conditions induced a significant increase of the surface concentration of C=O (ketones) and COO (esters and acidic) functional groups, while C-O-C (ether) groups remained constant. It is shown that after plasma functionalization, when the surface concentration of C=O and COO are above a critical value, a strong correlation appears between the concentration of these polar groups, the wettability and the adhesion potential.
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