Hydrophobic to superhydrophobic and hydrophilic transitions of Ar plasma‐nanostructured PTFE surfaces

Abstract Production of superhydrophobic polytetrafluoroethylene (PTFE) by Ar plasma etching is challenging as it leads to defluorination, resulting in a hydrophilic surface. The effect of radiofrequency power, treatment time, impurity, and surface temperature on Ar plasma‐treated PTFE was investigated for producing a large‐area superhydrophobic PTFE surface. To avoid impurity and substrate temperature effects, a single electrode‐based arrangement with a sacrificial PTFE disc behind the specimen was used for plasma discharge. After 5 min treatment at 100 W, the surface became superhydrophobic (water contact angle = 156°) due to the formation of isotropic nanostructures. However, 30 min of plasma treatment caused severe chemical changes resulting in a hydrophilic surface (water contact angle = 14°). A yellowish layer was formed on the surface due to crosslinking, redeposition of fluorocarbon species, and iron impurities from the plasma system confirmed by X‐ray photoelectron spectroscopy analysis.