Fabrication of robust and versatile superhydrophobic coating by two-step spray method: An experimental and molecular dynamics simulation study

Abstract The low mechanical durability of superhydrophobic surfaces has been considered as a serious limitation to develop these unique coatings in industrial applications. Despite the promising results, the main challenges are related to the fabrication of stable and practical superhydrophobic coatings with proper adhesion using the facile approaches. In the present study, the superhydrophobic surface was fabricated using the two-step spray method with a WCA of 160°. At the first step of this method, the hydrophobic resin was sprayed as an adhesive layer. Then, at the next step, the stearic acid-modified Alumina nanoparticles were sprayed on the adhesive layer. Important coating parameters such as stability of spray suspension and thermal stability of coating were investigated. The results showed that the decreasing agglomeration rate of particles during the spraying enhances the more uniform distribution and hydrophobicity of the layer. Besides, increasing the temperature, especially after 250 °C, reduced the roughness and hydrophobicity of the layers due to the decomposition of stearic acid. Meanwhile, molecular dynamics (MD) simulation was applied to investigate the adsorption of stearic acid on the Alumina surface along with its interaction with water molecules. The results can propose the effective mechanism of suspension stability and thermal stability on the growth and formation of coatings. Also, the findings of this study can help to fabricate superhydrophobic coatings on various substrates using the two-step spray method with wear resistance.