Ultrahydrophobic Textiles Using Nanoparticles: Lotus Approach

It is well established that the water wettability of ma-terials is governed by both the chemical composition and the geometrical microstructure of the surface.1 Traditional textile wet processing treatments do in-deed rely fundamentally upon complete wetting out of a textile structure to achieve satisfactory perform-ance.2 However, the complexities introduced through the heterogeneous nature of the fiber surfaces, the nature of the fiber composition and the actual con-struction of the textile material create difficulties in attempting to predict the exact wettability of a par-ticular textile material. For many applications the ability of a finished fabric to exhibit water repellency (in other words low wettability) is essential2 and po-tential applications of highly water repellent textile materials include rainwear, upholstery, protective clothing, sportswear, and automobile interior fabrics. Recent research indicates that such applications may benefit from a new generation of water repellent ma-terials that make use of the “lotus effect ” to provide ultrahydrophobic textile materials.3,4 Ultrahydropho-bic surfaces are typically termed as the surfaces that show a water contact angle greater than 150°C with very low contact angle hysteresis.4 In the case of tex-tile materials, the level of hydrophobicity is often determined by measuring the static water contact angle only, since it is difficult to measure the contact angle hysteresis on a textile fabric because of the high levels of roughness inherent in textile structures