Fabrication of superhydrophobic and superoleophilic polybenzoxazine-based cotton fabric for oil–water separation

Superhydrophobic material involves the fabrication of appropriate roughness and low surface energy. Studies concerning enhancing the attachment between substrates and low surface energy material have been reported. Hence, it might also be feasible to make low surface energy material as an interface binder to enhance the attachment. In our work, the simple dip-coating method was used to fabricate polybenzoxazine (PBZ)/SiO2-coating cotton (PBZSC) fabric for rapid oil–water separation. The surface morphology and wettability of the PBZSC fabric as well as the properties of the separation were explored using various methods. These results demonstrated that PBZSC fabric not only had excellent thermal properties, but also maintained excellent superhydrophobicity (WCA > 150°) under various harsh conditions which was mainly attributed to higher surface roughness contributed by SiO2 and lower surface energy, heat resistance as well as acid and alkali resistance from PBZ resin, respectively. More importantly, the separation conducted by the PBZSC fabric not only showed great recycle property, but also separated a series of oil and water mixtures with up to 96% separation efficiency. Therefore, it is anticipated that this low-cost PBZSC fabric will be readily and widely utilized in designing multifunctional membrane for large-area oil-spill cleanup without using fluoropolymers or silicones.