Recent Advances in the Methods for Designing Superhydrophobic Surfaces

The investigations of superhydrophobicity and self-cleaning surfaces have been given a lot of attention in the last few decades. The surfaces having water contact angle larger than 90° are termed as hydrophobic surfaces and those which exhibit contact angle higher than 150° are said to be superhydrophobic. Such surfaces were first observed in nature in various plants and animals, for example, lotus leaf-like structures. Water repellence of various materials have shown great influences on various applications such as self-cleaning, anti-ageing, water-oil separation, water corrosion in electrical industry, water proof textiles, controlled transportation of fluids, etc. Generally, surface micro/nanostructuring combined with low surface energy of materials leads to extreme anti-wetting properties. The hundreds of research articles and more than 450 patents on the subject of nature mimicking self-cleaning surfaces prove the potential of this topic. Self-cleaning property depends on both surface morphology and surface chemistry. For achieving superhydrophobic surfaces, we can, typically, either increase the roughness of the intrinsically hydrophobic material or tune desired roughness and morphology on hydrophilic surfaces. Depending on such parameters a water droplet on the surface attains either Wenzel or Cassie-Baxter state. For the preparation of superhydrophobic surfaces, various physical and chemical methods have been successfully used. Methods such as hydrothermal process, using various templates, plasma surface modifications, physical and chemical vapour deposition, layer by layer deposition, electrospinning and sol-gel processing have been used for achieving desired roughness and surface chemistry on various © 2015 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. substrates. In this field of research, various fabrication methods have significant role in deciding the extent of superhydrophobic behaviour of the surface, depending on the material which is used for the processing. In this chapter, the most recent developments in various methods used for fabricating superhydrophobic surfaces are presented along with their advantages and limitations.