Facile Synthesis of Nanostructured Self-Regenerative Superhydrophobic Coatings

The current study endeavors facile synthesis of robust nanostructured superhydrophobic coatings. Different feedstock materials (Cu, Al, Zn, SS316, NiCrCSiBFe) are coated using flame-spraying at different spraying distances and constant pressure (1 bar). The surface modulation of flame-sprayed coating is done using 1H,1H,2H,2H-perfluorooctyltriethoxysilane (FOTES). The coating's topology alters from multi-order hierarchal coral reef-like morphology for Al and Zn to flattened topology for SS316 and NiCrCSiBFe. The size and density of nanostructures show significant transition with variation in feedstock and spraying distance. The analysis of particle-laden flames shows characteristic variations in particle temperatures and velocity profiles. The morphological alternations are related to physiochemical characteristics, resulting in in-situ particle vaporization and nucleation. Post silanization, Al and Zn coatings deposited at higher spraying distance show significant de-wetting traits (theta > 155 degrees) with lowest contact angle hysteresis and sliding angle (<5 degrees). Coatings show extremely low adhesion of 2-4 mu N with water droplets, which is considerably lower than lotus leaf (18 mu N). Both coatings show extreme resilience in simulated rain, withstanding droplet impacts for more than 2 h without any loss of superhydrophobicity and outstanding abrasion resistance due to self-regeneration behavior. The present study highlights a synthesis of a viable route for the development of robust superhydrophobic coatings for various applications.