Versatile and robust poly(ionic liquid) coatings with intelligent superhydrophilicity/superhydrophobicity switch in high-efficient oil-water separation

Superhydrophilic/superhydrophobic surfaces with unique superiority have been applied for oil-water separation over a long time. Facing the increasingly complicated requirements in diverse separation fields, developing intelligent surfaces with switchable superhydrophilic/superhydrophobic properties are highly needed. In this work, versatile and robust poly(ionic liquid) (PIL) coatings were designed and a series of intelligent materials with switchable superwettabilities were generated for high-efficient oil-water separation. The PIL coatings were obtained by polymerization of PIL monomer on the roughened GO sheets, for which were realized by the immobilization of Fe 3 O 4 nanoparticles. Three materials with different structures (cotton fabric (CF), nylon fabric (NF) and cotton ball (CB)) were chosen as the coating substrates. After “dip-coating” process, the PIL coated materials (PCMs) exhibited switchable superhydrophilic/superhydrophobic performances due to the anion-responsive behavior of PIL and the roughness enhanced effect. Thus, the PCMs showed high-efficient separation performances upon multiple oil-water separation cycles, and the separation could be switched between “water-removing” and “oil-removing” by anion exchange. Meanwhile, the PIL@CF had high permeate fluxes, which could separate layered water-oil mixtures rapidly under gravity; the PIL@NF had the highest separation efficiency; the PIL@CB possessed great potential to be used as efficient absorbents for water/oil adsorption and recycle.