Biomimetic Murray nanofiber membranes with pore/wetting double gradient for ultrafast directional water transport and evaporative textiles

Directional water transport (DWT) textiles, possessing moisture-wicking and evaporative fast-drying capabilities, help in creating a comfortable microenvironment for the human body. However, fabricating synthetic materials that follow Murray's law and replicate the pore gradient of vascular plants remains challenging, thereby impeding the achievement of a good combination of moisture conduction, fast drying, and osmosis resistance. In this study, DWT membranes comprising three layers of pore/wetting gradients were constructed using a straightforward electrospinning/netting technique. The inner and intermediate layers, comprising hydrophobic polyurethane (PU) and hydrophilic PU-hydrolyzed polyacrylonitrile (PU-HPAN) nanofibers with average diameters of 1.83 µm and 255 nm, respectively, were prepared via electrospinning. Furthermore, the superhydrophilic outer layer (HPAM) comprised HPAN and a blend of acrylic acid/acrylamide with an average diameter of 76 nm. This layer was prepared via the electro-netting of dilute solution with high electrical conductivity, resulting in a spontaneous and continuous water transport, coupled with rapid drying. The DWT membranes exhibited an ultrahigh one-way transport capability (R) of 1270%, achieving an evaporation rate of 0.86 g h−1. Additionally, they demonstrated rapid drying within 16 min, effectively preventing reverse osmosis under pressure. Therefore, these membranes can be applied for moisture wicking, water extraction, and micro fluidic control.