A study of the chemical and physical effects of ion implantation of micro-porous and nonporous PTFE

In a comparative study, N2+, Ar+ and Ca+ ion implantation was used to modify subcutaneous augmentation material (SAM), a micro-porous form of polytetrafluoroethylene (PTFE) and nonporous PTFE, with a view to assessing the effect of ion implantation on the chemical and physical structure of these materials as well as the effect of porosity on the response to ion implantation. SAM is used as an implant material for reconstructive surgery, and this study is part of a larger investigation into methods of modifying SAM to improve its tissue integration potential. Ion implantation was carried out at an energy of 30 keV, with doses of 1×1015 and 1×1016 ions/cm2. SRIM.2000.39 was used to simulate N2+, Ar+ and Ca+ implantation of PTFE. X-ray photoelectron spectroscopy (XPS) was used for the characterisation of chemical structural changes in the ion-implanted samples, while scanning electron microscopy (SEM) was used for the characterisation of physical structural changes. Rutherford backscattering spectroscopy (RBS) was used to determine the elemental surface composition of Ca+ and Ar+ implanted samples. Advancing and receding water contact angles were measured using the sessile drop method. XPS analysis showed that all ion-implanted samples had undergone chemical structural changes. Some variation was noted between samples implanted with different ions and at different doses. SEM analysis showed that physical structural changes were independent of ion mass with some variation between doses. Water contact angle measurements showed some variation between samples, with nonporous samples showing dose dependent behaviour.