Controllable fabrication of superhydrophobic TiO2 coating with improved transparency and thermostability

Superhydrophobic surfaces generally require a combination of surface topography and low surface energy, where a thick surface coating on the substrate usually leads to loss of its transparency or color. We demonstrated a convenient and controllable strategy for fabricating the superhydrophobic TiO2 coatings with improved transparency on glass substrates. The TiO2 coating possesses hierarchical morphology assembled by radial nanowires, which effectively constructed a rough surface topography and sufficiently captured air pockets. After thermal annealing and modification with stearic acid, the as-prepared TiO2 coating on glass exhibited excellent superhydrophobicity with a water contact angle (WCA) as high as 157°, low roll-off angle of 2° and good bounce performance. The growth process of the hierarchical TiO2 coating was studied. The double control over roughness and transparency of the superhydrophobic coatings on the glass substrate are achieved by adjusting the original concentration of titanium source. Moreover, the coatings remain superhydrophobic even heated at temperatures up to 200 °C for 30 min.