The lotus leaf is known as one of the natural self-cleaning plants, which can easily roll off water but not oil droplets. Herein, a simple chemical bath deposition method to fabricate superhydrophobic and strong oleophobic surfaces was presented on porous substrates such as fabrics and nickel foams. The resultant substrates exhibited excellent superhydrophobicity and good oil repellency. More significantly, such surfaces possessed self-cleaning property for water, as well as to oils such as glycerol and rapeseed oil.In nature, many surfaces are superhydrophobic with water contact angles larger than 150°and sliding angles lower than 10°. Lotus leaves, rice leaves, and cicada wings are some representative surfaces with superhydrophobic properties, which generally represent in the form of self-cleaning.1 However, such a self-cleaning effect will be deteriorated by various degrees when the surface is contaminated by oily waste liquids in practical applications. 2 Although superoleophobicity has been found in the case of fish scale and shark skin in nature, such oil repellency exists only underwater. There are very few reports on oil repellency in air, 3 because the lower surface tension of oil makes the lyophobicity harder achieve than in the case of water. 4 Therefore, it is urgent, necessary, and challenging to design and fabricate superhydrophobic surfaces with antioily contamination for industrial applications.To achieve these properties, improving the oleophobicity of superhydrophobic surfaces is of utmost significance. It is well known that wettability is governed by both the chemical composition and geometric structure of a solid surface.
5According to three models that describe the contact angle of a droplet on a surface, 68 lower surface energy and proper roughness are necessary for achieving superoleophobic surface. In general, some special structures such as a re-entrant or overhanging geometries are indispensable to obtain appropriate roughness for superoleophobicity. 911 Besides, fluorinated chemicals with extremely low surface energies, such as perfluoroalkylthiol and perfluorinated silane, are also essential to obtain a superoleophobic surface. So far, only a few of methods have been developed to fabricate both superhydrophobic and superoleophobic surfaces (also called superamphiphobic) on various substrates, including electrochemical method, 12 electrodeposition, 13 and so on. 1416 Superoleophobic surface on a metal substrate has been widely reported because of the facile construction of roughness by chemical etching and deposition.
17Superoleophobic fabrics have also been prepared by using the multiscale structure concept. 18 Moreover, a self-healing superamphiphobic surface has been obtained by coating the fluorocontaining polymers on the fabric.19 Compared to the conventional superhydrophobic surface, 2023 these as-prepared surfaces with superhydrophobictiy and strong oleophobicity are exciting since a great progress has been made on lowering the surface free energy and constructing more fine su...
