A bio-inspired method to fabricate the substrate-independent Janus membranes with outstanding floatability for precise oil/water separation

The lotus leaf has the Janus wettability and outstanding floatability at multiphase interface. The ingenious design on lotus leaf surfaces enlightens us to fabricate the superhydrophobic/superhydrophilic binary cooperative membrane. Making use of the poor permeability of the candle soot, deposition of a layer of candle soot enables to form the Janus membrane with anisotropic wettability on different surfaces. After fixed by the hydrophobic polymer, the superhydrophobic/superhydrophilic binary cooperative membranes are prepared successfully on various membranes, such as filter paper, cotton fabric and copper mesh. The Janus membrane exhibits excellent interfacial floatability at the immiscible oil–water interface as a separator, thus affording high-performance immiscible oil/water separation without applied external pressure.