Polymer Surface Modification:  Topography Effects Leading to Extreme Wettability Behavior

The surface oxidation of polyethylene (PE) and the surface reduction of Teflon (FEP) were studied with regard to the surface topography of the film samples that were used and the resulting water wettability. Anodized aluminum membranes were used as nanomolds to impart fibrillar topographies to the polymer surfaces. Water contact angles of smooth PE (θA/θR = 93°/75°) decreased to θA/θR = 68°/46° upon oxidation with potassium chlorate/sulfuric acid solution. Smooth FEP film samples changed from θA/θR = 111°/100° to θA/θR = 64°/45° upon reduction with sodium naphthalide solution. Contact angles of PE and FEP increased to 172°/160° and 174°/172°, respectively, upon introduction of the fibrillar topography and both decreased to ∼0°/0° after oxidation and reduction, respectively. That topography can be used as a tool in polymer surface modification is emphasized.