Fabrication of modifier-free superhydrophobic surfaces with anti-icing and self-cleaning properties on Ti substrate by anodization method

Superhydrophobic titanium (Ti) and its alloys have attracted considerable attention due to their application potentials; however, it is very difficult to obtain directly superhydrophobic surfaces on the Ti substrate by the anodization method. In the present work, TiO2 pinecone-like micro/nanostructures (TPSs) were fabricated on the Ti substrate by the anodization method. It was found that the sample surfaces without chemical modification were superhydrophilic and then became superhydrophobic after their exposure to air for a long time. After the high-temperature annealing treatment, the time required for the superhydrophilic to superhydrophobic wettability transition with the maximum water contact angle (WCA) of similar to 153 degrees and sliding angle (SA) of similar to 0 degrees was reduced from 81 days to 63 days. The surface chemistry and morphology analysis indicated that the wettability transition mainly occurred by the adsorption of organic compounds from ambient air and the trapped air in the microstructure. Furthermore, the superhydrophobic surfaces had excellent anti-icing and self-cleaning properties and long-term stability