Radiation-induced grafting of acrylic acid onto expanded poly(tetrafluoroethylene) membranes

Expanded poly(tetrafluoroethylene) (ePTFE) is currently being applied in facial reconstruction surgery. One requirement for the use of ePTFE membranes in soft tissue replacements is establishment of a well-bonded interface with the surrounding bone. However, ePTFE is classified as bioinert, thus lacking in biomimetic properties which may result in poor osseointegration at the bone–implant interface. Thus, the introduction of functional groups onto the polymer surface was carried out in the current study using radiation induced grafting of acrylic acid (AA) yielding graft yields of up to 40%. This resulted in reducing the hydrophobicity (advancing contact angle reduced from 116 to 92°). XPS revealed that the grafted PAA was highly crosslinked. The effects of grafting conditions (dose, monomer concentration, as well as solvent) on the grafting outcome were evaluated. Grafting of tertbutyl acrylate (tBA) was investigated but low graft yields were obtained and this was shown to be unaffected by the solvent used during the grafting process. The mechanical properties of the AA grafted membranes were altered significantly and were dependent on the testing conditions (wet or dry).