Superhydrophobic polytetrafluoroethylene surfaces with leaf-like micro-protrusions through Ar + O2 plasma etching process

• Superhydrophobic PTFE surfaces were prepared after Ar + O2 plasma treatment.
• Leaf-like micro-protrusions were observed post 4 h plasma treatment through FESEM.
• Micro-Raman and XPS studies indicate no change in chemical identity of the surface.
• Highest CA of 158° was obtained for maximum average surface roughness of 1.96 μm.
• Wenzel's theory explains superhydrophocity of low-energy-roughened PTFE surfaces.

Polytetrafluoroethylene (PTFE/Teflon) is an excellent material in applications demanding high thermal and chemical stability. Imparting water repellency in such materials can be an advantage when they are used for biomedical and electric insulation applications. Using Ar + O2 plasma treatment superhydrophobic PTFE surfaces were prepared. The plasma treated PTFE samples exhibited a change in the surface morphology showing ‘leaf-like’ micro-protrusions in the field emission scanning electron microscopy (FESEM) analysis. 3D Profilometry results showed an increase in the average surface roughness until a treatment time of 4 h. The highest value of the water contact angle was obtained at the maximum average surface roughness for 4 h treatment. Chemical analysis by micro-Raman and X-ray photoelectron spectroscopy for the untreated and Ar + O2 plasma treated PTFE samples did not show much variation in their chemical structures. The report asserts that a change in the surface roughness is sufficient enough to create superhydrophobic surfaces of PTFE.