Material behaviourLow-temperature air plasma modification of chitosan-coated PEEK biomaterials

Novel chitosan-coated PEEK biomaterials were prepared by air plasma modification. Low-temperature plasma effect on changes of specific thermal, mechanical and adhesive properties of polyetheretherketone (PEEK) was investigated. The topography and surface roughness of the prepared materials were determined using an optical profilometer. The wetting and energetic properties of biomaterials were studied by means of advancing and receding contact angles measurements and then apparent surface free energy (and its components) were evaluated applying the LWAB (Lifshitz-van der Waals Acid Base) theory and contact angle hysteresis model. After air plasma treatment a fairly hydrophobic character of PEEK was changed to strongly hydrophilic one. Significant differences in the wettability and thermal stability of samples were observed. However, hardly any differences in excellent mechanical properties were noticed. The profilometer images showed an increase in the surface roughness of PEEK modified surface due to the change of cross-link density, elasticity and formation of additional polar groups on the surface. Plasma treated polyetheretherketone surfaces had better adhesive features and stable chitosan coating was created. Modification by chitosan improved antibacterial properties, inherent haemostatics and polymer biocompatibility. These advantages allowed to obtain new attractive biomaterials from the same polymer differing in properties for a wide spectrum of applications, mainly regenerative medicine and orthopedic surgery.