Controllable wettability surface of ZnO nanorods on glass substrates prepared by simple wet chemical method for patterned processing

The surface wettability can be well controlled by coatings and roughness. In this work, we prepared ZnO film and nanorods with different precursor concentration range from 0.002 mol/L, 0.02 mol/L to 0.2 mol/L on glass substrates by simple wet chemical method. We found that the range of contact angle transitions was significantly enlarged by growing nanorods on ZnO seed layer. Besides, the wettability is reversible that the ZnO nanorods turns to hydrophilic by ultraviolet irradiation and recovered to hydrophobic after heating at 180 ℃. Our results showed the nanorods with the precursor concentration of 0.02 mol/L exhibited fastest speed of the reversible transition. According to the switchable wettability, the aggregated large droplet on the hydrophobic solid surface tends to swallow other microdroplets in the opposite direction of the jet trajectory, and then, the surface was easily non-contact patterned, which is conducive to the further realization of large-scale applications as smart surfaces.