Superhydrophobic surfaces preparation methods

A Translucent and Superhydrophobic Surface Prepared with a Sol-Gel Method Based on Alumina Nanoparticles... 

The combination of changes in surface chemistry and surface roughness can enhance stimuli-responsive wettability. Here, we have presented a simple one-step method to prepare apolybenzoxazine-silica nanoparticle film, displaying reversible wettability via a solvent treatment. The difference in the water CAs of the same composite film, before and after solvent treatment was achieved to be 19° with silica content of 120 phr. Compared with a traditional superhydrophobic surface, the as-prepared film can be modified to show not only hydrophobicity but also a high adhesion force with water. Our results are considered to be significant in terms of their importance to academic research and industrial applications. 

ZnO A simple method of electrochemical deposition was adopted to prepare conductive hydrophobic ZnO thin films [504]. These ZnO films were fabricated by overpotential electrochemical deposition at room temperature, and the surface modified by a (flu-oroalkyl)silane showed superhydrophobic properties. The prepared thin films were treated with a methanol solution of hydrolyzed (heptadecafluorode-cyl)trimethoxysilane (CH30)3Si(CH2)2 (CF2)7CF3, 1.0 wt %) for 3 h and subsequently heated at 100 °C for 1 h. Wettability studies revealed that the surface of the as-prepared thin films showed a contact angle (CA) for water of 128.3 1.7°, whereas the superhydrophobic surface with a water CA of 152.0 2.0° was obtained by (fluoroalkyl) silane modification [504]. 

In order to prepare hydrophobic and superhydrophobic surfaces, femtosecond laser was used to pattern the metallic surface and after irradiation the surface was subjected to silanization using dip coating in order to reduce its surface energy and make it inherently hydrophobic. Details on the silanization method used can be found elsewhere [27]. 

Superhydrophobicity is an important issue both for science and industry. Fabrication of such surfaces has been studied for more than ten years. Generally, there are some problems with obtaining stable superhydrophobic layers on solids. Many methods have been devised for such surface preparation [1]. 

Wang and Shu [2] obtained transparent superhydrophobic antireflec-tive layers for solar cells. The layers were constructed on a glass substrate using layer-by-layer deposition of a polyelectrolyte. The superhydrophobic sol-gel system was prepared by hydrolyzing tetraethoxysilane and then reacting it with hexamethyldisilazane. The water contact angle measured on the layers obtained by the spin coating method was up to 163° on most superhydrophobic surfaces. Moreover, the transmittance of this layer was about 96%. 

Liu, J., Huang, W, Xing,Y, Li, R., Dai,J., 2011a. Preparation of durable superhydrophobic surface by sol-gel method with water glass and citric acid. J. Solgel Sci.Technol. 58,18. 

Based on colloidal monolayers of polystyrene spheres, we have prepared various two-dimensional nano-structured arrays by solution routes and electrodeposition. Many ordered structured arrays generated using these methods are of surface roughness on the nano- and micro-scales, and could be superhydrophobic or superhydrophilic. The nano-devices based on such nano-structured arrays would be waterproof and selfcleaning, in addition to their special device functions. In this article, taking silica, ZnO and gold as examples of the insulators, semiconductors and metals, respectively, we report some of our recent results to demonstrate controlled wettability and superhydrophobicity of two-dimensional ordered nano-stmctured arrays with centimeter square-size based on colloidal monolayers. 

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