A facile approach to fabricate a stable superhydrophobic film with switchable water adhesion on titanium surface

A simple process of thermal oxidation and self-assembly modification was developed to fabricate a stable superhydrophobic film with controllable adhesion on titanium surface. Pure titanium plate was first heat treated in atmospheric environment at 900 °C, 1000 °C and 1100 °C respectively for a certain time, then air cooled. The subsequent air-cooling process separated the flaky yellow oxide layer formed on titanium plate during the oxidation from the substrate and a rough titanium oxide surface with micrometer and nanometer-scale hierarchical structures was obtained. The following immersion process in N-octadecyltrichlorosilane solution endowed the surface with excellent water repellence, raised its contact angle up to 166° and reduced its slide angle as low as 2°. What's more, by controlling heat temperature and time, the surface's superhydrophobicity switched from sticky state to sliding state. Field-emission scanning electron microscopy (FE-SEM) and contact angle measurement were used to characterize the morphological features and wettability of the as-prepared surface respectively. Immersion test in corrosive liquids and abrasion test with sandpaper have a further exhibition of its chemical stability and mechanical durability. The result is meaningful to a wider range of future applications of superhydrophobic titanium surface in industry and real life.