Preparation and surface wettability of TiO2 nanorod films modified with triethoxyoctylsilane

Nanostructured TiO2 arrays were prepared through a facile and environmentally friendly hydrothermal method on fluorine-doped tin oxide coated glass substrates with tunable surface morphologies without using any catalysts, seeds or templates. Their crystal structure, surface morphology, compositions and wettability were investigated by X-ray diffraction, field emission scanning electron microscope, X-ray photoelectron spectroscope and contact angle measurements, respectively. It is found that the concentration of hydrochloric acid has a great influence on the morphology and wettability of TiO2 nanorod films. Typically, the film prepared with 7.0M HCl exhibits a high water contact angle of 157.3±1.5° with an advancing contact angle of 154.2±1.3° and a receding contact angle of 161.2±1.3° and a small sliding angle of 7° after hydrophobic treatment. The Cassie theory was used to analyze the hydrophobic phenomenon of the as-prepared film, and it reveals that only about 9% of the water surface is contacted with the TiO2 film and the remaining 91% is contacted with the air cushion, which is reasonable for the hydrophobicity of a TiO2 nanorod film.