Fabrication of polydopamine-boehmite modified superhydrophobic coating for self-cleaning, oil-water separation, oil sorption and flame retardancy

A facile approach for fabricating multifunctional superhydrophobic coating was developed through a simple dip-coating process. The boehmite particles (BMPs) were adhered and modified onto stainless steel (SS) mesh through polydopamine (PDA), which was formed by the oxygen-induced polymerization of dopamine (DA). Therefore, the roughness structure (SS-PDA@BMPs mesh) was obtained. Meanwhile, due to the catechol group of the PDA, cetylamine (CTA) with low surface energy and amino group was grafted onto PDA via the Michael addition reaction to construct the superhydrophobic coating (CTA@PDA@BMPs). The effects of the morphology of BMPs, the ratio of BMPs to DA, the reaction time, and the concentration of CTA on superhydrophobicity of SS-CTA@PDA@BMPs mesh were discussed, which showed the water contact angle of 164° and the sliding angle of 3° for the SS-CTA@PDA@BMPs mesh fabricated under optimal conditions. The SS-CTA@PDA@BMPs mesh with great chemical stability and mechanical durability displayed excellent self-cleaning property and oil/water separation efficiency. When the PU sponge was coated with CTA@PDA@BMPs coating by the same process, the superhydrophobic PU sponge was obtained, which exhibited superior reusability and flame retardancy property. Thus, the prepared superhydrophobic materials are multifunctional and environmentally friendly.