Superhydrophobic Polybenzoxazine/TiO2 Coatings with Reversible Wettability for High-Flux Oil/Water Separation

Superhydrophobic polybenzoxazine (PBZ)/TiO2 coatings with reversible wettability were fabricated by blending eugenol/siloxane-based benzoxazine (E-aptmds) with TiO2 nanoparticles through spin coating and thermal curing processes. The resulting coatings could switch between superhydrophobicity and superhydrophilicity through alternate ultraviolet (UV) irradiation and heating treatment cycles. The PBZ/TiO2 coating-modified stainless steel mesh (PBZ/TiO2 mesh) had ultra-high oil/water separation fluxes of over 54,000 L/m2 h only by gravity for several heavy oil/water mixtures. Meanwhile, the PBZ/TiO2 mesh could efficiently collect various light oils from water with separation efficiencies of over 96.0%. Additionally, the PBZ/TiO2 mesh could purify methylene blue-contaminated water through UV irradiation. Owing to the self-cleaning property of the PBZ/TiO2 mesh, chemical and powdery pollutants could be easily dispelled. Furthermore, the as-prepared mesh exhibited strong durability under harsh treatments including high temperature, acid/alkali immersion, or organic solvent immersion. Hence, the PBZ/TiO2 mesh owns a bright prospect in the application of oil/water separation.