Autohesion of plasma treated semi-crystalline PEEK: Comparative study of argon, nitrogen and oxygen treatments

[Display omitted] ▶ In this study, the self-bonding strength of semi-crystalline PEEK films was found to be enhanced by pretreatment of the films using RF plasma in Ar, N2 and O2 gases. The maximum bond strength was achieved when PEEK was treated with Ar plasma for 4min and was still increasing with treatment time. Bond strength correlated positively with total oxygen concentration, positively with C–O group concentration and negatively with C=O group concentration. The positive correlation of strength with the polar component of surface energy is consistent with the correlation with total oxygen. Semi-crystalline polyetheretherketone (PEEK) is of interest for providing hermetic sealing of implantable medical devices. Self bonding or autohesion is achieved by mild temperature and pressure treatment and is potentially useful to form joints in the encapsulation of active medical implants. The surfaces of PEEK films were treated in a radio-frequency (RF) plasma containing one of the gases Ar, N2 and O2, to achieve surface activation. The bond strength developed over the interface of PEEK films was evaluated by lap-shear testing. The effects of plasma conditions on the surface morphology, composition, and properties were determined using the profilometer, contact angle measurements, X-ray photoelectron spectrometry (XPS) and scanning electron microscopy (SEM). Results obtained show that plasma treatment of the PEEK films enhances their bonding strength, with the Ar treated films exhibiting the highest bond strength and nitrogen the lowest. Bond strength was shown to correlate positively with total oxygen content, with C–O group concentration and with the polar component of surface energy. Bond strength correlated negatively with CO group concentration.