Engineering durable superhydrophobic layered double hydroxide coatings via incorporation of a nano-formulated quinoline-based ionic liquid for enhanced corrosion protection.

In this study, a newly nano-formulated quinoline-based ionic liquid (NILq) was successfully synthesized and characterized. NILq was incorporated into a Ni-Al layered double hydroxide (LDH) matrix to fabricate a superhydrophobic coating, LDH-NILq-SA, on carbon steel via one-step electrodeposition to increase its corrosion resistance in marine and industrial infrastructure applications. The synthesized ionic liquid was characterized by FTIR, 1H NMR, 13C NMR and HRMS spectroscopy. The NILq exhibited a spherical morphology observed by TEM and a highly positive surface charge of +27.8 mV from zeta potential measurements, indicating excellent colloidal stability. The incorporation of NILq modulated the LDH growth behavior, generating a hierarchical nano-architecture capable of stabilizing the Cassie-Baxter wetting state and enhancing long-term interfacial durability. The optimized LDH-NILq-SA coating demonstrated exceptional superhydrophobicity with a sliding angle and water contact angle of 0.5°, 166.5° respectively. Surface investigation by SEM and AFM revealed a well-developed layered structure characteristic of layered double hydroxides with optimized surface roughness (R a = 369.9 nm). The coating exhibited prominent chemical stability, maintaining superhydrophobicity over pH range (1-13), and remarkable mechanical durability, withstanding 1050 mm of abrasion under 5 kPa load. The optimized coating exhibited exceptional thermal stability, maintaining superhydrophobicity up to 200 °C with full regenerability after thermal degradation. Electrochemical measurements performed in 0.5 M NaCl solution demonstrated that the 30 ppm LDH-NILq-SA coating achieved a protection efficiency of 99.5%, significantly outperforming the NILq-free LDH-SA coating. This work presents an effective strategy for fabricating durable, high-performance superhydrophobic coatings with promising applications in corrosion protection for marine and industrial infrastructure.