Role of adsorbed water on PEEK surfaces prior to − and after − atmospheric plasma activation

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. Atmospheric pressure plasma is a promising dry process to activate polymer surfaces, to improve wettability, and adhesion toward many kinds of coatings. Water desorption before treatment, and preventing its readsorption after treatment, allow guaranteeing efficient activation as well as a reduced, if not suppressed aging of the surface.