Hydrophobic drawings on hydrophilic surfaces of single crystalline titanium dioxide: surface wettability control by mechanochemical treatment

The surface wettability control at arbitrary positions of solid surfaces is extremely interesting from the point of view of both science and technology. Recently, we found that a position-controlled high-speed hydrophilic to hydrophobic transition was possible on single crystalline anatase-TiO2(001) surfaces applying a new 'wet rubbing' method. This new kind of mechanochemical surface treatment realized switching of the hydrophilic surface with water-contact angle 3 degrees to a hydrophobic surface with 80 degrees angle within 1 min at arbitrary positions on the surface. Consequently, hydrophobic drawings could be made by a paintbrush on hydrophilic surfaces. (C) 2000 Elsevier Science B.V. All rights reserved.