A stable superhydrophobic and superoleophilic Cu mesh based on copper hydroxide nanoneedle arrays

A superhydrophobic and superoleophilic copper mesh was prepared via a simple electrochemical route. Copper substrates were anodized in a 1 mol/L NaOH aqueous solution to produce a rough thin film of Cu(OH)2 nanoneedle arrays and then the film was reacted with 1H,1H,2H,2H-perfluorooctyltriethoxysilane to form a very thin and stable hydrophobic coating layer. X-ray photoelectron spectroscopy (XPS) data revealed the coordination of silicon atoms with cuprate (CuO) molecules present on the anodized substrate. The water contact angle of the perfluoroalkylsilane-modified nanoneedle surface was approximately 170°. Furthermore, the superhydrophobicity was maintained after wet treatments in aqueous solutions with a wide pH range of 2−14 and after a long storage time of 4 months. This excellent durability and long-term reliability, which was unattainable in comparable samples modified with n-dodecanethiol or n-dodecanoic acid, could be interpreted with the formation of a stable and dense surface modification layer via a condensation reaction between –SiOEt and –CuOH and subsequent polymerization among the ethoxysilane adsorbates. Preliminary studies of the dynamic permeation behaviors of water and non-polar solvents exhibited a potential use of the hybrid copper mesh as a filtering layer for oil and water separation.