An integrated Janus porous membrane with controllable under-oil directional water transport and fluid gating property for oil/water emulsion separation

Directional liquid transport driven by the interface or surface property of Janus porous membrane owes great significance to many applications such as separation technology, fog collection, and energy devices. The Janus porous membranes have successfully demonstrated an efficient oil self-transport in water and also enable directional water transport in air or oil-water interface. However, the directional water transport in oil environment is a challenge because of the relatively low surface tension of oil. In this work, a novel integrated Janus porous membrane is developed for the first time to construct self-propelled energy free directional water transport in oil system that successfully demonstrated to be a facile “water diode” for under-oil water one-way regulation. Additionally, this Janus porous membrane exhibits an interesting tunable fluid-gating behavior for either water or oil, using optimized conditions. The current findings may promote the innovation towards directional liquid transport science and will open up new avenues for diverse on-demand liquids manipulation scenarios such as water-in-heavy oil emulsion separation.