Superhydrophobic surfaces

Abstract

Superhydrophobicity was first observed in nature on a lotus leaf and some other plants when their leaves would not get wet. The main reason for that phenomenon was the unique surface structure of the lotus leaf and also the presence of a low surface energy material on the surface of the leaf. In order to achieve superhydrophobic surface or coating, the surface must possess hierarchical micro and nano roughness and low surface energy at the same time. Hierarchical micro and nano scale roughness will trap air on the surface that will cause an increase in the water contact angle and low surface energy will decrease the tendency of water to bond with the surface. So almost all the methods to achieve superhydrophobicity consist of two requirements of a hierarchical surface roughness as well as presence of a low surface energy material. These surfaces have many practical applications, from industrial to biomedical applications, including water/oil separation, self-cleaning, drag reduction, antifogging, anti-bacteria, anti-fouling, anti-icing, corrosion resistance, as well as many applications in industries such as marine, oil, and gas, aerospace, biomedicine etc. Hence, superhydrophobic surfaces, which can be achieved by surface modifications and/or surface coatings, have become very interesting in the last decade. The important issues and challenges in the field of superhydrophobic surfaces is stability and robustness of the surfaces.

Superhydrophobic and icephobic surfaces prepared by RF-sputtered polytetrafluoroethylene coatings

“…Indeed, superhydrophobic surfaces (water contact angle θ > 150º) have shown promising antiicing performance [6]. A variety of methods have been used to fabricate superhydrophobic surfaces [7][8][9][10][11][12]. There are two main approaches to generate superhydrophobic surfaces: (i) creation of a rough surface from low surface energy materials and (ii) creation of a rough surface followed by a low surface energy material coating step.…”

“…Anodic aluminum oxide has been proposed as a suitable industrial process for use in the burgeoning field of nanotechnology [21] for developing nano-pore structure films with advantage of improvement of corrosion and wear resistance [22][23][24]. Low surface energy coatings can be produced by deposition of low surfaceenergy materials such as fluorocarbons and silicones precursors [8,10,25].…”

Nano-scale superhydrophobicity: suppression of protein adsorption and promotion of flow-induced detachment

“…A large number of techniques have been developed to produce different superhydrophobic surfaces for study 4 , a small number have been developed into products. 5,6 Protein adsorption is the first stage in biological contamination of surfaces, with cells binding to a pre-adsorbed protein layer before proliferating and spreading. Surfaces that hinder or obstruct this early adsorption process would reduce cell growth.…”

Advances in Bio-inspired Tribology for Engineering Applications

“…Further, research based on unique functions of a lotus leaf for cardiovascular applications in biomedical field are being carried out by Maani et al [83] where they employ CFD modeling technique to investigate the effect of surface pattern to control blood flow adhesion. The nonwettable character has been claimed in biomedical applications ranging from blood vessel replacement to wound management [84].…”