title: Facile synthesis, growth mechanism and reversible superhydrophobic and superhydrophilic properties of non-flaking CuO nanowires grown from porous copper substrates.
abstract: Reversible superhydrophobic and superhydrophilic surfaces based on porous substrates covered with CuO nanowires are developed in this study. A facile thermal oxidation method is used to synthesize non-flaking bicrystalline CuO nanowires on porous copper substrates in static air. The effects of thermal oxidation temperature and duration are systemically studied. The growth mechanism of the obtained non-flaking CuO nanowires is presented and the compression stress is believed to be the key driving force. The wettability of the CuO nanowires after chemical modification with trichloro(1H,1H,2H,2H-perfluorooctyl)silane is systemically investigated. The porous substrates covered with CuO nanowires exhibit excellent superhydrophobic performance with almost no water adhesion and no apparent drag resistance, and a maximum static water contact angle of 162 ± 2° is observed. Moreover, a rapid reversibly switchable wettability between superhydrophobic and superhydrophilic states is realized by the alternation of air-plasma treatment and surface fluorination. The porous substrates covered with CuO nanowires will find promising applications in surface and corrosion protection, liquid transportation, oil-water separation, and self-cleaning surfaces.
authors: Department of Mechanical and Biomedical Engineering, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong.
authors: Qiao bao
authors: Qb
authors: Zhang
authors: Daguo
authors: D
authors: Xu
authors: Tak Fu
authors: TF
authors: Hung
authors: Kaili
authors: K
authors: Zhang
mesh_terms: D003300:Copper / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D036103:Nanotechnology / Q000191:economics / Q000379:methods; D053770:Nanowires / Q000737:chemistry* / Q000648:ultrastructure; D010084:Oxidation-Reduction; D016062:Porosity; D012821:Silanes / Q000737:chemistry; D013696:Temperature; D014867:Water / Q000737:chemistry; D017155:Wettability
chemical_list: D012821:Silanes; D014867:Water; D003300:Copper; C030973:cupric oxide