A review of fabrication techniques for superhydrophobic coatings

Abstract

Superhydrophobic surfaces have emerged as a pivotal focus of modern materials science. These surfaces are notable for their unique wetting behavior and wide array of potential applications in fields such as self-cleaning coatings, anti-corrosion protection, drag reduction, anti-icing technologies, and oil-water separation. Inspired by natural models such as lotus leaves, water striders, and Salvinia molesta, these surfaces combine low surface energy materials with hierarchical micro/nanostructures to achieve water contact angles exceeding 150°. This dual scale roughness traps air pockets beneath water droplets, enabling the "lotus effect," whereby droplets roll off surfaces, removing contaminants. The development of superhydrophobic coatings is particularly important in the context of metal corrosion because economic and environmental factors have created a demand for safer, more sustainable alternatives. A wide variety of fabrication techniques have been developed, including top-down methods, such as laser ablation and etching, and bottom-up strategies, such as sol-gel deposition and chemical vapor deposition. However, many approaches are limited by complexity, cost, scalability, or environmental impact. Furthermore, the practical application of these coatings presents challenges concerning durability, material compatibility, performance under environmental stressors, and the use of fluorinated compounds, which pose ecological risks. This review critically examines current methodologies for fabricating superhydrophobic surfaces. It evaluates the underlying principles, advantages, and limitations of these methods with respect to mechanical robustness, scalability, and application-specific demands. Particular emphasis is placed on the importance of multiscale surface structuring and selecting inherently hydrophobic, low-energy materials to create functionally resilient coatings. Additionally, the work explores the limitations of current testing standards and suggests that a unified framework for evaluating mechanical wear, environmental resistance, and hydrophobic retention is essential for accelerating the transfer of technology from the laboratory to the industrial scale. The review highlights novel strategies such as biomimetic design, incorporating self-healing materials, and integrating superhydrophobic coatings with multifunctional technologies as promising future directions. Ultimately, the success of superhydrophobic surface technologies depends on a multidisciplinary effort balancing performance metrics with environmental responsibility and economic feasibility to unlock their transformative potential across diverse sectors.