Argon plasma treatment-induced grafting of acrylic acid onto expanded poly(tetrafluoroethylene) membranes

Expanded poly(tetrafluoroethylene) (ePTFE) is used in facial reconstruction surgery. For some specific applications ePTFE is required to interface with the underlying bone. However, ePTFE is classified as bioinert thus limiting integration at the bone-tissue interface. The incorporation of functional groups onto the ePTFE surface was carried out in the current study using argon plasma treatment-induced grafting of acrylic acid (AA) to improve integration. High surface coverage (grafting extent from XPS of up to 90%) was achieved and resulted in high hydrophilicity and high water uptake (up to 470% of the grafted PAA mass). The contribution of species present in the plasma to the incorporation of functional groups onto the ePTFE surface was evaluated with charged species observed to play an equally important role to neutral species in this study. The effects of sample position in the plasma chamber as well as the effect of grafting parameters (plasma power, monomer concentration, and reaction time) on the grafting outcome were evaluated. The mechanical properties of the AA grafted membranes under tensile, compression and nanoindentation were evaluated.