Metallic superhydrophobic surfaces

We have reported here on the preparation of two-scaled metallic superhydrophobic surfaces. Apparent contact angles as high as 150° were observed. The modified Cassie-Baxter approach predicts apparent contact angles which are very close to... 

Electrochemical Fabrication of Superhydrophobic Surfaces on Metal and Semiconductor Substrates... 

Superhydrophobic surface, electrochemistry, metal, metal oxide, conducting polymer... 

Alternatively, it is possible to apply polymer films for this purpose. Of course, such polymers must also have the ability to strongly reduce the surface free energy. Ruorine-containing polymers appear to be suitable to endow metal oxide surfaces with superhydrophobic properties, but most of them are insoluble. An exception is Teflon AF, which can be dissolved in perfluorinated solvents and applied by spin-... 

The application of the coatings by dipping the roughened aluminium samples in a diluted polymer solution seems to be suitable and effective to provide large aluminium sheets with superhydrophobic surface properties. Coating films to control the surface properties, e.g. the wetting behavior, and to prevent metal substrate... 

Liu YH, Wang XK, Luo JB, Lu XC (2009) Fabrication and tribological properties of superhydrophobic surfaces based on porous silicon. Appl Surf Sci 255 9430-9438 Loni A, Barwick D, Batchelor L, Tunbridge J, Han Y, Li ZY, Canham LT (2011) Extremely high surface area metallurgical-grade porous silicon powder prepared by metal-assisted etching. Electrochem Solid State Lett 14 K25-K27... 

J. Ma, X.Y. Zhang, D.P. Wang, D.Q. Zhao, D. W. Ding, K. Liu and W.H. Wang. Superhydrophobic metallic glass surface with superior mechanical stability and corrosion resistance. Appl. Phys. Lett., 104, 173701 (2014). 

In recent years, due to a plethora of potential applications of superhydro-phobicity in daily life, many elforts have been taken to fabricate artificial superhydrophobic surfaces. Depending on the application and material, different methods have been employed to create superhydrophobic smfaces [8], Most of these methods involve either creating a micro/ nano-structme on an inherently hydrophobic material [9,10] or treating a specific micro/nano-structure with a hydrophobic coating [11-14]. For instance, for metallic materials, roughened surfaces have to be coated with low surface energy materials. 

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]. 

Artificial superhydrophobic surfaces have been introduced in the past decade and a variety of production methods (self-assembly, lithography, sol-gel) and materials (polymers, metals, Si, etc.) have been suggested. 

Superhydrophobicity is usually a result of hydrophobic (low surface energy) coating (e.g. wax or Teflon) combined with the roughness that magnifies the effect of the coating. However, superhydrophobicity has been reported also for intrinsically hydrophilic (metallic) surfaces. In this case, superhydrophobicity arises from the surface roughness only. The typical size of roughness details in superhydrophobic surfaces is of the micron scale. 

Azim S. S., Sathiyanarayanan S. and Venkatachari G. (2006), Anticorrosive properties of PANI-ATMP polymer containing organic coating , Ptxrg. Org. Coatings, 56,154—8. Bai H., Li C. and Shi G. (2008), Electrochemical Fabrication of Superhydrophobic Surfaces on Metal and Semiconductor Substrates , J. Adhes. Sci. TechnoL, 22,1819-39. 

As can be seen from the data presented in Table 3, metal surfaces structured with quasi periodic spikes, as well as irregular combination of micro-and nanoroughness, meet the criteria of superhydrophobic surfaces. 

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