Smart regulation of substance permeability through porous membranes is highly desirable for membrane applications. Inspired by the stomatal closure feature of plant leaves at relatively high temperature, here we report a nano-gating membrane with a negative temperature-response coefficient that is capable of tunable water gating and precise small molecule separation. The membrane is composed of poly(N-isopropylacrylamide) covalently bound to graphene oxide via free-radical polymerization. By virtue of the temperature tunable lamellar spaces of the graphene oxide nanosheets, the water permeance of the membrane could be reversibly regulated with a high gating ratio. Moreover, the space tunability endows the membrane with the capability of gradually separating multiple molecules of different sizes. This nano-gating membrane expands the scope of temperature-responsive membranes and has great potential applications in smart gating systems and molecular separation.

Anisotropic interfaces with opposite properties provide numerous unusual physical chemical properties that have played irreplaceable roles in broad domains. Here, we rationally designed an anisotropic Janus membrane with opposite wettability and special interpenetrating interface microstructure, which shows a unidirectional liquid penetration "diode" performance. Liquid is allowed to penetrate from lyophobic to lyophilic direction but is blocked in the reverse direction. Although conventional works suggested the liquid unidirectional penetration is driven by anisotropic wettability in heterogeneous interfaces, here, we theoretically and experimentally reveal that special interpenetrating topology plays another important role in liquid unidirectional penetration. This insight gives a general guide to build a series of Janus membranes for liquid unidirectional penetration with high hydraulic pressure rectification ratio. The liquid diode Janus membrane indicates great promise for liquid manipulation, smart separation membranes, functional textiles, and other fields.

Inspired by the self‐cleaning phenomenon in nature biology, superwettable materials systems have been increasingly studied by multidisciplinary scientists in past two decades. Among various fabrication methods, electrospinning technology, with superior capability of comprehensive coordination of surface chemical composition and hierarchical micro/nanostructures, has been proved to be a versatile method to fabricate diverse fibrous materials with superwettability from polymers, ceramics, to composites. This review first introduces the progress of electrospinning technology in generating various hierarchical structured nanofibers. Then, the wetting theory of liquid on fibers and recent approaches toward fabricating bioinspired electrospun micro/nanofibers with superwettability are described. Based on the special wettability to different liquids, the electrospun nanofibrous materials play significant roles in liquid mixtures separations, water collection, unidirectional liquid penetrations, and in environmentally responsive materials. Finally, the challenges and promising prospects on electrospun superwettability nanofibrous materials are highlighted.

The separation of organic liquid mixtures is achieved by Cu(OH) nanoneedle-covered copper mesh based on the difference of the liquid surface tension. The as-prepared membrane allows the penetration of organic liquid with smaller surface tension and blocks the higher. Thus, the effective separation of these two organic liquids can be achieved.

A hybrid membrane with asymmetric microtopology and anisotropic wettability realizes highly efficient fog collection.

No abstract

A superhydrophobic/superhydrophilic dual-membrane separation system has been designed based on an opposite and complementary combination to achieve a high-flux, high-efficiency, continuous oil/water separation.

Precisely regulating water and molecule permeation through membranes is of crucial significance in broad domains such as water filtration and smart reactors. Comparing with routine stiff membranes, stimuli‐response polymers endow porous membranes with various gating properties, but most of these membranes have only one‐way gating performance, that is, either positive or negative. Here poly(N‐isopropylacrylamide) (PNIPAM) grafted graphene oxide (GO) membranes with reversible positive/negative gating regularity are constructed by simply tuning the molecule grafting density. The water and small molecule permeance of the membranes can be regulated by adjusting environment temperature. Based on this tunable thermoresponsive gating regularity, a bidirectional fluidic controlling system is designed by integrating a positive membrane and a negative membrane, which can be employed as a self‐adaptive gating reactor. This strategy provides an insight into constructing smart gating membranes with extraordinary properties, showing promising applications in micro/nanofluidic valves and temperature sensitive biochemical reactors.