Cardanol-based polybenzoxazine superhydrophobic coating with improved corrosion resistance on mild steel

[Display omitted] •A cardanol-based polybenzoxazine superhydrophobic coating was prepared on mild steel by spraying and thermal curing method.•The superhydrophobic coating shows superior self-cleaning property and thermal stability.•The coating performs high corrosion resistance during prolonged immersion. Cardanol-based polybenzoxazine and amino-modified silica nanoparticles were combined to develop a superhydrophobic coating (PC-a/SiO2) on mild steel for anti-corrosion coating application. The thermal curing behavior of the PC-a/SiO2 coating was studied by Fourier transform infrared spectroscopy. The durable PC-a/SiO2 coating with a static water contact angle of 162.8 ± 2.9° could retain its superhydrophobic property even after heat treatment at 250 °C for 1 h or immersion in 3.5 wt% NaCl aqueous solution for 10 days. The electrochemical measurement results indicate that the PC-a/SiO2 coating exhibits superior corrosion resistance during prolonged immersion in 3.5 wt% NaCl aqueous solution. It is expected that the cardanol-based polybenzoxazine superhydrophobic coating is promising for practical applications of corrosion resistance.