Superhydrophobic Surfaces by Microtexturing: A Critical Review

Abstract

Superhydrophobicity is a property of surfaces characterized by extreme water repellence and it is observed in highly textured low surface energy materials. The surface roughness can be varied widely. There are several ways by which superhydrophobicity can be achieved on various kinds of surfaces. Polymer surfaces have a wide range of applications and are a good candidate for making superhydrophobic surfaces. Superhydrophobic surfaces are well known for their self-cleaning and anti-icing properties so that water droplets roll off the surface taking away all the external contaminant particles that are present on the surface along with it. Surfaces that have a static water drop contact angle of greater than 150° and a roll-off angle of less than 10° can be termed as superhydrophobic surfaces. The various methods for making superhydrophobic surfaces that have been developed are templating, lithography, plasma treatment, electrochemical deposition, layer-by-layer self-assembly, sol-gel deposition, wet chemical reaction, hydrothermal reaction, chemical vapor deposition, and electrospinning. Many physical and chemical methods have been used to design and fabricate superhydrophobic surfaces. However, surfaces are prone to damage by scratches, abrasion, or even brief contact with fingers, and, therefore, surfaces might lose their superhydrophobicity. Hence, improving mechanical robustness and self-replenishment of superhydrophobic surfaces upon damage is an active area of research. Potential applications of superhydrophobic surfaces include biomaterials, microelectronics, microfluidics, coatings, textiles, and so on. Various superhydrophobic surfaces have been discussed in this paper, namely poly(dimethylsiloxane), polytetrafluoroethylene, etc., and their applications.