Double layered superhydrophobic PDMS-Candle soot coating with durable corrosion resistance and thermal-mechanical robustness

Nature-inspired superhydrophobic coatings with typical Cassie-Baxter contacts garner numerous interests for multifunctional applications. However, undesirable poor mechanical and thermal stability are still crucial bottlenecks for real-world employment. This work introduces a cost-effective, fluorine free and versatile strategy to achieve double-layered PDMS agglutinated candle soot coating with superior water-repellent superhydrophobicity. The surface morphologies, chemical compositions and wettability behaviors were investigated in detail. The mechanical stability, chemical stability and durable corrosion resistance of the fabricated PDMS-CS coating were evaluated through friction, calcination and electrochemical impedance spectroscopy. The results demonstrate a remarkably enhanced mechanical robustness and corrosion resistance, indicating PDMS units can act as an effective agglutinating agent between candle soot and underlying substrate. The synergistic effect of PDMS agglutination, porous network nanostructures and extremely low surface energy of incomplete combustion induced candle soot deposition contribute to the eventually robust corrosion resisting coating, which greatly increases the possibility for practical applications.