Fabrication of superhydrophobic and oleophobic Al surfaces by chemical etching and surface fluorination

Hierarchical Al surfaces were fabricated using three different kinds of alkaline-based chemical etching processes. The surface morphology changes to a needle-like microstructure or to nanoscale flakes on a microscale porous structure depending on the chemical solution used. These surfaces were characterized by field-emission scanning electron microscopy, X-ray diffraction analysis, X-ray photoelectron spectroscopy, and contact angle measurements. After the hydrophobic treatment, the etched Al surface shows non-wetting properties, exhibiting a static contact angle over 150° and a dynamic contact angle less than 5° for deionized water. Oleophobic properties for diiodomethane and N,N-dimethylformamide are exhibited by all etched Al surfaces.