A spray pyrolysis method for fabrication of superhydrophobic copper substrate based on modified-alumina powder by fatty acid

Superhydrophobicity is the tendency of a surface to repel water drops. Due to this unique property, superhydrophobic surfaces can be used in many applications, such as water-resistant surfaces, antifogging surfaces, anti-icing surfaces, and anti-corrosion surfaces. In this study, superhydrophobic surfaces were fabricated by a spray pyrolysis method with water contact angles ˃ 160° and contact angle hysteresis less than 3°. For this purpose, the alumina nanoparticle modified by a fatty acid was dispersed in an alcohol solvent and coated on the substrate. Palmitic acid and stearic acid were selected as the modifying hydrophobic agents on the alumina surface. The chemical bonding between the surface of the alumina and the fatty acid was confirmed by Fourier-transform infrared spectroscopy (FT-IR) patterns. The influences of alcohol solvents on spray pyrolysis deposition of the modified-alumina were also studied by altering alcohol solvents (methanol, ethanol, and 2-propanol). Dynamic light scattering (DLS), scanning electron microscopy (SEM), and roughness analysis results showed that the increase in stability of spray suspension can enhance the coverage of films, which consequently increase the roughness and hydrophobicity of the layers. Wetting measurements showed that stearic acid is a better hydrophobic agent for modifying the surface of alumina, and 2-propanol is a convenient alcohol solvent for the fabrication of a superhydrophobic surface due to the highest water contact angle and lowest surface free energy of its film. The method is both easy and inexpensive, and we propose that this work has potential industrial applications for the fabrication of superhydrophobic surfaces on the various scale of copper substrates.