Surface analysis of chemically-etched and plasma-treated polyetheretherketone (PEEK) for biomedical applications

Surface modifications of polyetheretherketone (PEEK) made by chemical etching or oxygen plasma treatment were examined in this study. Chemical etching caused surface topography to become irregular with higher roughness values Ra and Rq. Oxygen plasma treatment also affected surface topography, unveiling the spherulitic structure of PEEK. Ra, Rq and surface area significantly increased after plasma treatment; topographical modifications were, nonetheless, moderate. Wetting angle measurements and surface energy calculations revealed an increase of wettability and surface polarity due to both treatments. XPS measurements showed an increase of surface oxygen concentration after both treatments. An O:C ratio of 3.10 for the plasma-treated PEEK surface and 4.41 for the chemically-etched surface were determined. The results indicate that surface activation by oxygen plasma treatment for subsequent coating processes in supersaturated physiological solutions to manufacture PEEK for biomedical applications is preferable over the chemical etching treatment.