Water motion and movement without sticking, weight loss and cross-contaminant in superhydrophobic glass tube.

We report that a simple fabrication of a superhydrophobic nanosurface consisted of a grass-like silica thin film on the inner wall of a glass tube and its feature in water motion and water movement. The glass tube with a superhydrophobic inner wall can make the water flow with friction-drag reduction and completely preventing water sticking. Transferring water by this tube did not cause weight loss at all. Therefore, aqueous solutions containing high content metal ions were cross-moved without washing the tube used and no cross-contamination occurred after cross-movement. Furthermore, in an inside diameter of 6.0 mm glass tube where the half-length of the inner surface is covered by superhydrophobic nanograss and the other half is an unmodified hydrophilic surface, the water droplets flowing down from the hydrophilic side can be stopped spontaneously at the hydrophilic-superhydrophobic boundary as if there is an invisible flow-stopping fence built inside the glass tube.