RESUMO
Smart membranes with protection and thermal-wet comfort are highly demanded in various fields. Nevertheless, the existing membranes suffer from a tradeoff dilemma of liquid resistance and moisture permeability, as well as poor thermoregulating ability. Herein, a novel strategy, based on the synchronous occurrence of humidity-induced electrospinning and electromeshing, is developed to synthesize a dual-network structured nanofiber/mesh for personal comfort management. Manipulating the ejection, deformation, and phase separation of spinning jets and charged droplets enables the creation of nanofibrous membranes composed of radiative cooling nanofibers and 2D nanostructured meshworks. With a combination of a true-nanoscale fiber (â¼70 nm) in 2D meshworks, a small pore size (0.84 µm), and a superhydrophobic surface (151.9°), the smart membranes present high liquid repellency (95.6 kPa), improved breathability (4.05 kg m-2 d-1), and remarkable cooling performance (7.9 °C cooler than commercial cotton fabrics). This strategy opens up a pathway to the design of advanced smart textiles for personal protection.
RESUMO
Skin-like functional membranes with liquid resistance and moisture permeability are in growing demand in various applications. However, the membranes have been facing a long-term dilemma in balancing waterproofness and breathability, as well as resisting internal liquid sweat transport, resulting in poor thermal-wet comfort. Herein, a novel electromeshing technique, based on manipulating the ejection and phase separation of charged liquids, is developed to create triboelectric nanostructured nano-mesh consisting of hydrophobic ferroelectric nanofiber/meshes and hydrophilic nanofiber/meshes. By combining the true nanoscale diameter (≈22 nm), small pore size, and high porosity, high waterproofness (129 kPa) and breathability (3736 g m-2 per day) for the membranes are achieved. Moreover, the membranes can break large water clusters into small water molecules to promote sweat absorption and release by coupling hydrophilic wicking and triboelectric field polarization, exhibiting a satisfactory water evaporation rate (0.64 g h-1 ) and thermal-wet comfort (0.7 °C cooler than the cutting-edge poly(tetrafluoroethylene) protective membranes). This work may shed new light on the design and development of advanced protective textiles.
RESUMO
Seawater desalination is a promising and sustainable solution to alleviate freshwater scarcity; however, most existing desalination membranes suffer from poor channel interconnectivity and toxic solvent processing and encounter a tradeoff dilemma of salt rejection and water flux. Herein, we report a unique and facile one-step green solvent/nonsolvent spinning methodology to assemble environmentally friendly polyamide nanofiber membranes with a precisely designed interconnective/stable channel structure and surface anti-wettability for seawater desalination. Direct electrospinning without any post-treatments via in situ introduction of fluorinated chemicals enables highly interconnective amphiphobic channels within polyamide membranes, and the incorporation of nonsolvent (diacetone alcohol) into polyamide/solvent (ethanol) spinning solutions endows the green alcohol-based polyamide membranes with a stable bonding structure and small pore size. The resultant green solvent/nonsolvent-spun polyamide nanofiber membranes show impressive liquid entry pressure (120.5 kPa) and vapor permeation (12.5 kg m-2 d-1), achieving robust seawater desalination performance with a salt rejection of 99.97% and permeate flux of 47.4 kg m-2 h-1. The facile one-step solvent/nonsolvent spinning strategy, highly interconnective amphiphobic channels, and green solvent-based environmental friendliness in this work can open opportunities for future polyamide membranes for practical applications in water purification.