Super hydrophobic surfaces have attracted the interest of scientists and engineers for both fundamental research and their practical applications, such as contamination prevention, self-cleaning, antifouling surface designs, anti-icing coatings, corrosion resistance of metals and their alloys, and biomedical and biological applications, among others. Coatings with hydrophobic surfaces can be fabricated by controlling their topographic features and surface energies. A surface’s water repellency is an important phenomenon in natural and technological processes. A super hydrophobic surface is defined by a water contact angle (WCA) greater than 150° and a sliding angle (SA) lower than 5°.1 There are plenty of super hydrophobic surfaces in nature, including lotus leaves, butterfly wings, duck feathers, etc.2 Inspired by nature, super hydrophobic surfaces can be derived by employing two kinds of approaches. In the first approach, the solid surface is chemically modified with a low-surface-energy material. In the second approach, nano- and micro-scale structures are created on the substrate to prevent water from completely being in contact with the surface. In this approach, the water droplets sit mostly on the air. Water droplets on super hydrophobic surfaces can be nearly spherical and therefore have a tiny liquid-solid contact area, leading to easy roll off. Based on Cassie’s law, which describes how simply roughing up a substrate increases the apparent contact angle of a surface, the formation of appropriate surface patterns on hydrophobic surfaces leads to a general change in their wettability, and the contact angle increases substantially.
Extensive research has been conducted to understand the formation of super hydrophobicity on various substrates.3, 4 Organic/inorganic hybrid coatings using the sol-gel technique provide a simple and cost-effective approach to functionalize different surfaces. The presence of aliphatic hydrocarbon or perfluoro chains in the sol-gel precursors can substantially decrease the surface energy of the derived coatings. The mechanical properties of the films and adhesion strength to the substrate can be enhanced by crosslinking the silanol groups in the matrix and introducing chemical bonding between the coating and the substrate.5, 6