Integration of Janus Wettability and Heat Conduction in Hierarchically Designed Textiles for All-Day Personal Radiative Cooling.

Personal cooling textiles are a promising energy-free pathway for confronting serious heat-related public health threats and improving industrial worker productivity. Current cooling strategies mainly focus on passive daytime radiation, and there is a lack of research on all-day cooling methods which utilize synergistic radiative, conductive, and evaporative heat dissipation. Herein, we demonstrate a hierarchical polyurethane/silicon nitride fibrous membrane with Janus wettability fabricated via a scalable electrospinning method followed by single-side hydrophilic plasma treatment. High angular-dependent solar reflectance (91%) and human body infrared emittance (93%) allow for a temperature drop of ∼21.9 °C under direct sunlight and ∼2.8 °C at night compared with traditional cotton. The innovative integration of Janus wettability and heat conduction in hierarchically designed textiles ensures a minimum sweat consumption of 0.5 mL h-1, avoiding harmfully excessive perspiration. The excellent all-day cooling performance of this hierarchical textile presents great advantages for smart textile, energy-saving, and personal cooling applications.

Continuous, Spontaneous, and Directional Water Transport in the Trilayered Fibrous Membranes for Functional Moisture Wicking Textiles.

Directional water transport is a predominant part of functional textiles used for continuous sweat release in daily life. However, it has remained a great challenge to design such textiles which ensure continuous directional water transport and superior prevention of water penetration in the reverse direction. Here, a scalable strategy is reported to create trilayered fibrous membranes with progressive wettability by introducing a transfer layer, which can guide the directional water transport continuously and spontaneously, thus preventing the skin from being rewetted. The resulting trilayered fibrous membranes exhibit a high one-way transport index R (1021%) and a desired breakthrough pressure (16.1 cm H2 O) in the reverse direction, indicating an ultrahigh directional water transport capacity. Moreover, on the basis of water transport behavior, a plausible mechanism is proposed to provide insight into the integrative and cooperative driving forces at the interfaces of trilayered hydrophobic/transfer/superhydrophilic fibrous membranes. The successful synthesis of such fascinating materials would be valuable for the design of functional textiles with directional water transport properties for personal drying applications.

Biomimetic Aligned Micro-/Nanofibrous Composite Membranes with Ultrafast Water Transport and Evaporation for Efficient Indoor Humidification.

Humidifying membranes with ultrafast water transport and evaporation play a vital role in indoor humidification that improves personal comfort and industrial productivity in daily life. However, commercial nonwoven (NW) humidifying membranes show mediocre humidification capability owing to limited wicking capacity, low water absorption, and relatively less water evaporation. Herein, we report a biomimetic micro-/nanofibrous composite membrane with a highly aligned fibrous structure using a humidity-induced electrospinning technique for high-efficiency indoor humidification. Surface wettability and roughness are also tailored to achieve a high degree of superhydrophilicity by embedding hydrophilic silicon dioxide nanoparticles (SiO2 NPs) into the fiber matrix. The synergistic effect of the highly aligned fibrous structure and surface wettability endows composite membranes with ultrafast water transport and evaporation. Strikingly, the composite membrane exhibits an outstanding wicking height of 19.5 cm, a superior water absorption of 497.7%, a fast evaporation rate of 0.34 mL h-1, and a relatively low air pressure drop of 14.4 Pa, thereby achieving a remarkable humidification capacity of 514 mL h-1 (57% higher than the commercial NW humidifying membrane). The successful synthesis of this biomimetic micro-/nanofibrous composite membrane provides new insights into the development of micro-/nanofibrous humidifying membranes for personal health and comfort as well as industrial production.

A Trilayered Composite Fabric with Directional Water Transport and Resistance to Blood Penetration for Medical Protective Clothing.

Functional textiles with enhanced moisture management can facilitate sweat transport away from the skin to improve personal comfort. However, porous materials exhibit low capability of preventing the intrusion of external liquids, becoming a bottleneck in the design of medical protective clothing. Herein, a trilayered composite fabric based on a gradient wettability structure is demonstrated for directional water transport and resistance to blood penetration. The proposed fabric shows distinct advantages, including a high water breakthrough pressure of 2.43 kPa from the external side, an outstanding positive water transport index (1522%), and an antiblood penetration resistance of 2.71 kPa. Moreover, the fabric shows improved comfort with a high moisture transmission (320 g m-2 h-1) and desired water evaporation rate (0.36 g h-1). This work addressed the concern of directional water transport and resistance to blood penetration while providing a comfortable wearing microenvironment, leading to a promising research direction for multifunctional medical textiles.

Multi-scaled interconnected inter- and intra-fiber porous janus membranes for enhanced directional moisture transport.

HYPOTHESIS: Growing use of comfortable functional textiles has resulted in increased demand of excellent directional moisture (sweat) transport feature in textiles. However, designing such anisotropic functional textiles that allow fast penetration of sweat through one direction but prevent its movement in the reverse direction is still a challenging task. In this regard, fabrication of a novel Janus membrane with multi-scaled interconnected inter- and intra-fiber pores for enhanced directional moisture transport designed by a rational combination of superhydrophilic hydrolyzed porous polyacrylonitrile (HPPAN) nanofibers and hydrophobic polyurethane (PU) fibers via electrospinning may be a very useful approach. EXPERIMENT: PAN/PVP composite nanofibers were electrospun using PAN/PVP composite solution dissolved in DMF. After electrospinning, electrospun fibers were subjected extensive washing process to selectively remove PVP from the fiber matrix to develop highly rough and porous PAN (PPAN) nanofibers. The resultant PPAN nanofibers were then hydrolyzed to further improve their wettability. Finally, a layer of PU fibers was directly deposited on the HPPAN nanofibers via electrospinning to fabricate the subsequent Janus membrane. FINDINGS: The resultant PU/HPPAN Janus membranes display instant moisture transport in the positive direction with exceptional directional moisture transport index (R = 1311.3%), whereas, offer superior resistance (i.e. breakthrough pressure ≥17.1 cm H2O) to the moisture movement in the reverse direction. Moreover, a plausible mechanism articulating the role of inter- and intra-porosity for the enhanced directional moisture transport has been proposed. Successful fabrication of such fascinating Janus membranes based on the proposed coherent mechanism opens a new insight into the engineering of novel functional textiles for fast sweat release and personal drying applications.

Biomimetic Fibrous Murray Membranes with Ultrafast Water Transport and Evaporation for Smart Moisture-Wicking Fabrics.

Both antigravity directional water transport and ultrafast evaporation are critical to achieving a high-performance moisture-wicking fabric. The transpiration in vascular plants possess both of these features, which is due to their optimized hierarchical structure composed of multibranching porous networks following Murray's law. However, it remains a great challenge to simultaneously realize the ultrafast water transport and evaporation by mimicking nature's Murray networks in the synthetic materials. Here, we report a synergistic assembly strategy to create a biomimetic micro- and nanofibrous membrane with antigravity directional water transport and quick-dry performance by combining a multibranching porous structure and surface energy gradient, overcoming previous limitations. The resulting fiber-based porous Murray membranes exhibit an ultrahigh one-way transport capability ( R) of 1245%, a desired overall moisture management capability (OMMC) of 0.94, and an outstanding water evaporation rate of 0.67 g h-1 (5.8 and 2.1 times higher than the cotton fabric and Coolmax fabric, respectively). Overall, the successful synthesis of these biomimetic porous Murray membranes should serve as a source of inspiration for the development of moisture-wicking technologies, providing personal comfort in hot or humid environments.

Breathable and Colorful Cellulose Acetate-Based Nanofibrous Membranes for Directional Moisture Transport.

Textiles with excellent moisture transport characteristics play key role in regulating comfort of the body, and use of color in textiles helps in developing aesthetically pleasing apparels. Herein, we report an aesthetically pleasing and breathable dual-layer cellulose acetate (CA) based nanofibrous membranes with exceptional directional moisture transport performance. The outer layer was synthesized by subjecting CA nanofibers to hydrolysis and reactive dyeing processes, which converted moderately hydrophobic CA nanofibers into uniformly colored superhydrophilic CA nanofibers with an excellent wettability. In addition to excellent wettability and superhydrophilic nature, dyed CA (DCA) nanofibers also offered high color yield and dye fixation as well as considerable colorfastness performance against washing and light, thus, were used as the outer layer. However, pristine CA nanofibers were chosen as the inner layer for their moderate hydrophobicity. The subsequent CA/DCA nanofiber membrane produced a high wettability gradient, which facilitated directional moisture transport from CA to DCA layers. The resultant dual-layer nanofiber membranes offered a high color yield of 16.33 with ∼82% dye fixation, excellent accumulative one-way transport capacity (919%), remarkable overall moisture management capacity (0.89), and reasonably high water vapor transport rate (12.11 kg d-1 m-2), suggesting them to be a potential substrate for fast sweat-release applications.