Fabricating low-cost, robust superhydrophobic coatings with re-entrant topology for self-cleaning, corrosion inhibition, and oil-water separation

• Published in: Journal of colloid and interface science 2021-10, Vol.600, p.358-372
• Main Authors: Sow, Pradeep Kumar, Singhal, Richa, Sahoo, Priyanka, Radhakanth, Shriram
• Format: Article
• Language: English
• Subjects: Corrosion inhibition; Fly ash; Oil-water separation; Re-entrant; Self-cleaning; Substrate-versatile; Superhydrophobic
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2021.05.026

[Display omitted] The superhydrophobic surfaces with re-entrant microstructures are known to provide robust superhydrophobicity by enhancing the energy barrier for Cassie-Baxter to Wenzel transition. However, the fabrication of such structured surfaces often involves sophisticated techniques and expensive ingredients. Herein, a multifunctional, low-cost, and fluorine-free superhydrophobic coating with re-entrant surface topology was fabricated using fly ash (FA) and room-temperature-vulcanizing silicone. A systematic study was performed to evaluate the coating properties and durability. The robustness was evaluated as a function of particle size and inter-particle spacing. The performance in self-cleaning, corrosion inhibition and oil-water separation has been presented. The synthesized coatings are substrate-versatile and demonstrate superhydrophobic behavior. The close-packed coating of re-entrant FA particles attained via vibration compaction was seen to provide high robustness. The coatings retain their superhydrophobicity after multiple cycles of tape-peeling and exposure to environmental factors including temperature, pH, and UV radiation. These coatings exhibit excellent corrosion inhibition (corrosion efficiency > 99.999%), outperforming the majority of the previously reported superhydrophobic coatings. It also displays excellent self-cleaning property and high separation efficiencies in oil-water separation (>99%). We envision that such FA-based superhydrophobic coatings can solve the issues of synthesizing cheaper, sustainable, and robust superhydrophobic surfaces while simultaneously opening new avenues for FA utilization.