title: Robust nonsticky superhydrophobicity by the tapering of aligned ZnO nanorods.
abstract: The robust nonsticky superhydrophobicity of aligned nanoneedle films is reported. A facile, efficient, cheap, and available method based on the diffusion-limited crystal growth principle is proposed for controlling the tapering of ZnO nanorods, the profiles of which can be tuned effectively by synergetic control over reaction time and temperature in an extremely strong alkaline reaction system. The synthesized nanoneedle, nanopencil, and nanorod arrays are chosen for studying the effects of nanoscale topography on anti-droplet-sticking ability. After silanization, all of them show excellent quasi-static anti-droplet-stickiness, and water adhesion along the normal and lateral directions can be greatly reduced by the tapering of nanorods and eliminated by sharp nanoneedles. However, their antisticking stability is distinct under the droplet impact: the nanoneedle sample is still nonsticky but the nanorod sample loses its antisticking ability. Only ensuring the liquid/air interface is in the suspended nonwetting state is insufficient to obtain robust nonsticky surfaces, which also require extremely low solid-liquid van der Waals attraction.
authors.affiliation: Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123 (China); University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100049 (China).
authors.forename: Jian
authors.initials: J
authors.lastname: Tian
authors.forename: Yaping
authors.initials: Y
authors.lastname: Zhang
authors.forename: Jie
authors.initials: J
authors.lastname: Zhu
authors.forename: Zhongzhen
authors.initials: Z
authors.lastname: Yang
authors.forename: Xuefeng
authors.initials: X
authors.lastname: Gao
mesh_terms: D057927:Hydrophobic and Hydrophilic Interactions; D043942:Nanotubes / Q000737:chemistry*; D013499:Surface Properties; D013696:Temperature; D014867:Water / Q000737:chemistry; D015034:Zinc Oxide / Q000737:chemistry*
chemical_list: D014867:Water; D015034:Zinc Oxide
keywords: crystal growth; hydrophobic effect; nanostructures; superhydrophobicity; surface chemistry