Water repellent ZnO nanowire arrays synthesized by simple solvothermal technique

The authors report on the water repellent properties of quasialigned zinc oxide (ZnO) nanowire arrays grown by low-temperature solvothermal technique. The uniform and dense ZnO nanowires of average diameter similar to 75 nm have been found to have hexagonal wurtzite type structure. The as synthesized ZnO nanowire surfaces have hydrophilic nature with a water contact angle of 73 degrees +/- 3 degrees. The superhydrophobic behavior with a water contact angle of 145 degrees +/- 3 degrees of the nanowire arrays has been realized due to the reduction of surface free energy after being coated with an octadecyltrichlorosilane (OTS) monolayer. This work may be of huge importance from the viewpoint of both the understanding of the mechanisms involved and industrial applications. (C) 2009 Elsevier B.V. All rights reserved.