Plasma activation and self bonding of peek for the use in the encapsulation of medical implants

Polyether ether ketone (PEEK) and its composites have emerged as one of the main candidate materials for replacing titanium and its alloys for the encapsulating components of medical implants. PEEK, however, is a difficult material to bond without the use of adhesion promoting agents. Experiments based on the central composite rotatable design (CCRD) were used to find an optimum plasma surface modification treatment. X-ray photoelectron spectrometry (XPS), contact angle measurements and scanning electron microscopy (SEM) were used to provide surface molecular and thermodynamic information. Higher self bond strength of PEEK was found to correlate with higher relative oxygen concentration and total surface energy. Mechanisms for the autohesive bond formation were developed based on the oxidation of the surface. Polyether ether ketone (PEEK), which is one of the main candidate materials for replacing titanium for the encapsulation of medical implants components, requires surface activation in order to bond without the use of adhesion promoting agents. Experiments based on the central composite rotatable design were used to define an optimum plasma surface modification treatment. Bond strength correlates with surface oxygen concentration, and with surface energy.