Modification of polymers by plasma-based ion implantation for biomedical applications

We describe the modification of the polymer poly(aryl ether ether ketone) (PEEK) carried out with the aim of improving its performance for biomedical applications. Polymer samples were exposed to plasmas of oxygen, argon, hydrogen and deuterium by placing them on a substrate holder to which 15 μs pulses of 10 and 15 kV were applied. We found that the treatment with oxygen decreased the contact angle with water drops to nearly zero while argon modification decreased the contact angle to half that of the untreated material. The deeper the treatment the longer the time required to recover the original hydrophobic character. We also found that the hydrogen treatment produced the deepest modification and that the electrical resistivity of the treated material was the same for hydrogen and argon but was higher for oxygen. The effects of the treatment on the infrared spectrum were observed using attenuated total reflection infrared spectroscopy and it was shown that oxygen produces a distinctly different modification to that produced by the other gases.