Rewritable superhemophobic and superhemophilic wettability pattern based on titanium dioxide

Wettability patterns were fabricated on a surface based on titanium dioxide (TiO2) by etching of a Ti substrate with sulfuric acid and coating with TiO2 nanoparticles. Images obtained using a field emission scanning electron microscope and three-dimensional laser microscope reveal that the etched surface was covered with TiO2 nanoparticles and the surface roughness of TiO2-coated sample was lower value (2.51 mm) that of sample coated without TiO2 (3.19 mm), indicating that the surface roughness was decreased by coating with TiO2 nanoparticles. It was also confirmed that the crystal structure of TiO2-coated sample was rutile and anatase. The TiO2-coated sample modified with self-assembled monolayers (SAMs) showed a superhydrophobic property. The surface of the TiO2-coated sample gradually transformed into a superhydrophilic surface under UV irradiation because of the photocatalytic decomposition of the SAMs, and the decrease in the contact angle on the TiO2-coated sample was faster than that on the sample without TiO2 coating. In addition, the TiO2-coated sample produced renewable wettability patterns for blood, which demonstrate the great potential of this material in biomedical applications. (C) 2017 Elsevier B.V. All rights reserved.