Highly Flexible Monolayered Porous Membrane with Superhydrophilicity–Hydrophilicity for Unidirectional Liquid Penetration

Abstract

The ability to allow microliquid to penetrate in one direction but block in the opposite direction plays an irreplaceable role in intelligent liquid management. Despite much progress toward facilitating directional transport by multilayer porous membranes with opposite wettability, it remains difficult to achieve a highly multifunctional flexible membrane for highly efficient unidirectional liquid transport in different situations. Herein, a superhydrophilic–hydrophilic self-supported monolayered porous poly­(ether sulfone) (PES) membrane with special nano- and micropores at opposite surfaces is demonstrated, which can be used for unidirectional liquid transport. The results reveal that the competition of liquid spreading and permeation is critical to achieve directional liquid transport. The porous PES membrane, transformed with 70 vol % of ethanol in water (E/W-PES-70%), exhibits continuous unidirectional liquid penetration and antigravity unidirectional ascendant in a large range of pH values and can be used as “liquid diode” for moisture wicking. Moreover, the PES membrane can be prepared in a large area with excellent flexibility at room and liquid nitrogen temperature, indicating great promise in harsh environments. This work will provide an avenue for designing porous materials and smart dehumidification materials, which have promising applications in biomedical materials, advanced functional textiles, engineered desiccant materials, etc.

Wicking–Polarization‐Induced Water Cluster Size Effect on Triboelectric Evaporation Textiles

“…[ 9,10 ] Some recent studies have begun to pay attention to the water transport capacity, but the research on increasing the water evaporation rate is still relatively primitive. [ 11–13 ] Once the absorption layer is saturated, the liquid transport rate will slow down. Therefore, in order to ensure the dryness of clothes and the comfort of the wearer, increasing the water evaporation rate of textiles has become an important need.…”

“…[9,10] Some recent studies have begun to pay attention to the water transport capacity, but the research on increasing the water evaporation rate is still relatively primitive. [11][12][13] Once the absorption layer is saturated, the liquid transport rate will slow down. Therefore, in order to ensure the dryness of clothes and the comfort of the wearer, increasing the water evaporation rate of textiles has become an important need.The evaporation of liquid water requires rearrangement or destruction of the hydrogen-bonding network, thereby reducing the size of water clusters or splitting water clusters into water monomers, contributing to the fact that water molecules easily escape from liquid water.…”

Bioinspired Tunable Structural Color Film with Janus Wettability and Interfacial Floatability towards Visible Water Quality Monitoring

“…[ 1–5 ] To construct efficient superwettability surfaces, various approaches have been developed, including plasma treatment, layer‐by‐layer method, vapor deposition, etc. [ 6–13 ] In recent years, more attention has been paid to films with Janus wettability which have two faces with different properties. [ 14,15 ] Due to the applications in the fields of oil/water separation, unidirectional water flow, fog collection, and bubble aeration, this multisensory feature has prompted researchers to develop artificial membranes with Janus wettability.…”

River Branch Inspired Janus Textile with Moisture Wicking and UV Resistant Properties

“…According to this, a biomimetic fabric with three layers of tree-shaped structure was reported, showing great moisture management performance. (Miao et al 2018) In addition to traditional fabrics, many nano brous membranes (Fu et al 2020)have been applied in directional water transport, (Zhang et al 2020a)in which water can be transported from inner side to outer side. Another commonly used method is surface chemical modi cation, which forms energy gradient on the fabric surface to realize directional water transport.…”