Robust superhydrophobic needle-like nanostructured ZnO surfaces prepared without post chemical-treatment

Robust superhydrophobic ZnO surfaces with micro/nano hybrid hierarchical structures were synthesized on the stainless steel mesh by a facile single-step chemical bath deposition (CBD) method without using further low surface energy materials. The Taguchi L-16 experimental design was applied to evaluate the effects of reaction time, type and concentration of the additive, type of the chelating agent, and the molar ratio of the chelating agent to the initial zinc (II) ions. The prepared sample at the optimal conditions exhibited a sustainable and time-independent superhydrophobic behavior with the water contact angle (WCA) of 162.8 degrees +/- 2.5 degrees and contact angle hysteresis (CAH) of 1.8 degrees +/- 0.5 degrees. The XRD, SEM, TEM and FTIR analyses were used to characterize the prepared samples. Surface characterization using scanning elec tron microscopy (SEM) indicated accumulation of micro/nano branched ZnO needles on the substrate with the average diameters of similar to 85 nm. After 20 abrasion cycles the optimum sample indicated an excel lent mechanical robustness via exposure to the pressure of 4.7 kPa. A suitable chemical resistance to the acidic and basic droplets with the pH range of 4 and 9 was observed. (C) 2017 Elsevier B.V. All rights reserved.