Multi-bioinspired and Multistructural Integrated Patterned Nanofibrous Surface for Spontaneous and Efficient Fog Collection.

Harvesting water from untapped fog is a potential and sustainable solution to freshwater shortages. However, designing high-efficiency fog collectors is still a critical and challenging task. Herein, learning from the unique microstructures and functionalities of the Namib desert beetle, honeycomb, and pitcher plant, we present a multi-bioinspired patterned fog collector with hydrophilic nanofibrous bumps and a hydrophobic slippery substrate for spontaneous and efficient fog collection. Interestingly, hydrophilic nanofibrous bumps display a honeycomb-like cellular grid structure self-assembled from electrospun nanofibers. Notably, the patterned nanofibrous fog collector exhibits superior water-collecting efficiency of 1111 mg cm-2 h-1. The hydrophilic nanofibrous bumps increase the effective fog-collecting area, and the hydrophobic slippery substrate promotes quick transport of collected water in the desired direction reducing the secondary water evaporation, finally achieving rapid directional transport of tiny droplets and high-efficiency water collection. This work opens a new avenue to collect water efficiently and provides clues to research on the multi-bioinspired synergistical optimization strategy.

Controlled Alignment of Carbon Black Nanoparticles in Electrospun Carbon Nanofibers for Flexible Films.

Carbon nanofiber (CNF) films or mats have great conductivity and thermal stability and are widely used in different technological processes. Among all the fabrication methods, electrospinning is a simple yet effective technique for preparing CNF mats, but the electrospun CNF mats are often brittle. Here, we report a feasible protocol by which to control the alignment of carbon black nanoparticles (CB NPs) within CNF to enhance the flexibility. The CB NPs (~45 nm) are treated with non-ionic surfactant Triton-X 100 (TX) prior to being blended with a solution containing poly(vinyl butyral) and polyacrylonitrile, followed by electrospinning and then carbonization. The optimized CB-TX@CNF mat has a boosted elongation from 2.25% of pure CNF to 2.49%. On the contrary, the untreated CB loaded in CNF displayed a lower elongation of 1.85% because of the aggregated CB spots created weak joints. The controlled and uniform dispersion of CB NPs helped to scatter the applied bending force in the softness test. This feasible protocol paves the way for using these facile surface-treated CB NPs as a commercial reinforcement for producing flexible CNF films.

Thermal and Moisture Managing E-Textiles Enabled by Janus Hierarchical Gradient Honeycombs.

Moisture and thermal comfort are critical for long-term wear. In recent years, there has been rapidly growing attention on the importance of the comfortability in wearable electronic textiles (e-textiles), particularly in fields such as health monitoring, sports training, medical diagnosis and treatment, where long-term comfort is crucial. Nonetheless, simultaneously regulating thermal and moisture comfort for the human body without compromising electronic performance remains a significant challenge to date. Herein, a thermal and moisture managing e-textile (TMME-textile) that integrates unidirectional water transport and daytime radiative cooling properties with highly sensitive sensing performance is developed. The TMME-textile is made by patterning sensing electrodes on rationally designed Janus hierarchical gradient honeycombs that offer wetting gradient and optical management. The TMME-textile can unidirectionally pump excessive sweat, providing a dry and comfortable microenvironment for users. Moreover, it possesses high solar reflectivity (98.3%) and mid-infrared emissivity (89.2%), which reduce skin temperature by ≈7.0 °C under a solar intensity of 1 kW m-2. The TMME-textile-based strain sensor displays high sensitivity (0.1749 kPa-1) and rapid response rate (170 ms), effectively enabling smooth long-term monitoring, especially during high-intensity outdoor sports where thermal and moisture stresses are prominent challenges to conventional e-textiles.

Sweat Gland-Inspired Skin-like Fabric with Directional Water Transport and Durability for Efficient Personal Moisture Management.

Directional water transport textiles are an energy-free approach to improving the comfort of the human body. However, existing strategies mainly focus on enhancing the capacity of directional water transport, complicating the preparation process and limiting the long-term durability of textiles. Herein, a skin-like fabric inspired by sweat glands was prepared in one step by patterning printed hydrophobic paste on the fabric. This skin-like fabric has achieved the desired one-way water transport index (R, 721%), air permeability of 104 mm s-1, and water vapor transmission rate (298 g m-2 h-1). More significantly, due to the strong chemical bonds between the fabric and the coating, the skin-like fabric exhibited a high weight retention of 99.4% after 400 abrasion cycles and stable performance (R, 658%) after 25 h of washing. This work proposes a reliable way to prepare high-performance fabrics with durability, which show great potential for applications in functional textiles for personal moisture management.

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.

Highly Transparent Nanofibrous Membranes Used as Transparent Masks for Efficient PM0.3 Removal.

Currently, the quest for highly transparent and flexible fibrous membranes with robust mechanical characteristics, high breathability, and good filtration performance is rapidly rising because of their potential use in the fields of electronics, energy, environment, medical, and health. However, it is still an extremely challenging task to realize transparent fibrous membranes due to serious surface light reflection and internal light scattering. Here, we report the design and development of a simple and effective topological structure to create porous, breathable, and high visible light transmitting fibrous membranes (HLTFMs). The resultant HLTFMs exhibit good optical performance (up to 90% transmittance) and high porosities (>80%). The formation of such useful structure with high light transmittance has been revealed by electric field simulation, and the mechanism of fibrous membrane structure to achieve high light transmittance has been proposed. Moreover, transparent masks have been prepared to evaluate the filtration performance and analyze their feasibility to meet requirement of facial recognition systems. The prepared masks display high transparency (>80%), low pressure drop (<100 Pa) and high filtration efficiency (>90%). Furthermore, the person wearing this mask can be successfully identified by facial recognition systems. Therefore, this work provides an idea for the development of transparent, breathable, and high-performance fibrous membranes.

Lizard-Skin-Inspired Nanofibrous Capillary Network Combined with a Slippery Surface for Efficient Fog Collection.

Freshwater shortage is a critical global issue that needs to be resolved urgently. Efficient water collection from fog provides a promising and sustainable solution to produce clean drinking water, especially in the desert and arid regions. Nature has long served as our best source of inspiration for designing new structures and developing new materials. Herein, we report a strategy to design a novel Janus fog collector with a hydrophilic lizard-skin-like nanofibrous network upper surface and hydrophobic slippery lower surface using a simple and feasible method of coating and electrospinning. We analyze the forming law of the lizard-skin-like nanofibrous network structure on different substrates using electric field simulation. The resulting copper mesh-based Janus fog collector exhibits superior water-collecting efficiency (907 mg cm-2 h-1) and long-term durability, achieving directional transport of tiny droplets and high-efficiency water collection. However, there are few reports on the combination of the lizard-skin-like nanofibrous capillary network and slippery surface for efficient fog collection. Therefore, we believe that this work will open a new avenue to collect water efficiently and also provide clues to research on the lizard-skin-like nanofibrous network structure.

Honeycomb-Inspired Robust Hygroscopic Nanofibrous Cellular Networks.

Mimicking nature is a highly efficient and meaningful way for designing functional materials. However, constructing bioinspired nanofibrous 3D cellular networks with robust mechanical features is extremely challenging. Herein, a biomimetic, super-flexible, highly elastic, and tough nanofibrous membrane (NFM)-based water harvester is reported with a highly ordered honeycomb-inspired gradient network structure, self-assembled from electrospun spider-silk-like humped nanofibers. The resultant NFM exhibits super flexibility, high tensile strength (2.9 MPa), superior elasticity, and decent toughness (3.39 MJ m-3 ), allowing it to be used as the framework of hygroscopic materials. The resulting hygroscopic NFM displays excellent moisture absorption performance, which can be used as an efficient water harvester with a superhigh equilibrium moisture absorption capacity of 4.60 g g-1 at 95% relative humidity for 96 h, fast moisture absorption and transport rates, and long-term durability, achieving directional transport and collection of tiny water droplets. This work paves the way for the design and development of multifunctional NFMs with a honeycomb-inspired gradient network structure.

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.

Electrospun carbon nanofibers with multi-aperture/opening porous hierarchical structure for efficient CO2 adsorption.

HYPOTHESIS: Carbonaceous materials are believed to be excellent source for developing essential vessels for carbon dioxide (CO2) adsorption. However, most of the carbonaceous materials used for CO2 capture have particle form, which is hard to recycle and also may cause choking of the gas pipes. Additionally, they also either require chemical activation or attachment of any functional groups for proficient CO2 capture. Thus, facile fabrication of multi-aperture porous carbon nanofiber (CNF) based CO2 sorbent via combination of three simple steps of electrospinning, washing, and carbonization, may be an effective approach for developing efficient sorbents for CO2 capture. EXPERIMENT: PAN/PVP composite solution was electrospun, PVP was used as pore forming template and PAN was opted as nitrogen rich precursor for carbon during electrospinning process. Selective removal of PVP from the electrospun PAN/PVP fiber matrix prior to carbonization generated highly rough and extremely porous PAN nanofibers, which were then carbonized to develop multi-aperture/opening porous carbon nanofibers (PCNF) with ultra-small pores with average pore diameter of ~0.71 nm. FINDINGS: Synthesized PCNF exhibited high CO2 gas selectivity (S = 20) and offered superior CO2 adsorption performance of 3.11 mmol/g. Moreover, no apparent change in mass for up to 50 cycles of CO2 adsorption/desorption unveil the long-term stability of synthesized PCNF, making them a potential candidate for CO2 adsorption application.

Porous, flexible, and core-shell structured carbon nanofibers hybridized by tin oxide nanoparticles for efficient carbon dioxide capture.

HYPOTHESIS: Carbon based nanofibrous materials are considered to be promising sorbents for the CO2 capture and storage. However, the precise control of porous structure with flexibility still remains a challenging task. In this research, we report a simple strategy to develop tin oxide (SnO2) embedded, flexible and highly porous core-shell structured carbon nanofibers (CNFs) derived from polyacrylonitrile (PAN)/polyvinylidene fluoride (PVDF) core-shell nanofibers. EXPERIMENT: PAN/PVDF core-shell solutions were electrospun using co-axial electrospinning process. The as spun PAN core, and PVDF shell, with an appropriate amount of SnO2, fibers were stabilized followed by carbonization to develop SnO2 embedded highly porous and flexible core-shell structured CNFs. FINDINGS: The optimized CNFs membrane shows a prominent CO2 capture capacity of 2.6 mmol g-1 at room temperature, excellent CO2 selectivity than N2, and a remarkable cyclic stability. After 20 adsorption-desorption cycles, the CO2 capture capacity retains >95% of the preliminary value showing the long-term stability and practical worth of the final product. The loading of SnO2 nanoparticles in the carbon matrix not only enhanced the thermal stability of the precursor nanofibers, their surface characteristics, and porous structure to capture CO2 molecules, but also improves the flexibility of the CNFs by serving as a plasticizer for single-fiber-crack connection. Meaningfully, the flexible SnO2 embedded core-shell CNFs with excellent structural stability can prevail the limitations of annihilation and collapse of structures for conventional adsorbents, which makes them strongly useful and applicable. This research introduces a new route to produce highly porous and flexible materials as solid adsorbents for CO2 capture.

Exhaust reactive dyeing of lyocell fabric with ultrasonic energy.

Successful dyeing of lyocell, a biodegradable regenerated cellulose fiber, in fabric form is a challenging job. This article reports the successful reactive dyeing of lyocell fabrics with assistance of ultrasonic (US) energy via exhaust process, and compares the results with conventional (CN) exhaust dyeing process. Two commercial reactive dyes CI Reactive Red 195 and CI Reactive Blue 250 were used. Factors affecting dyeing such as fixation time, temperature and dyeing auxiliaries were compared for both processes. Under identical dyeing conditions, US dyed samples offered significantly much higher dyeing performance (i.e. color yield (>40%), dye fixation (>17%)) compared to CN process. Additionally, US exhaust process resulted in significant savings in terms of thermal energy (10 °C), capital (20 g/L NaCl and 2 g/L Na2CO3), and offered 33% higher production rate with yet improved dyeing performance (color yield up to ~7%, dye fixation up to ~5%) when compared under recommended conditions for two processes. Moreover, US dyeing poses considerably lower pollution (chemical oxygen demand 15-18% and total dissolved solids 32-36%) to the effluent in comparison to CN exhaust dyeing process. Furthermore, nearly identical colorfastness results and fiber surface morphology endorse use of US energy as a better, cost effective and relatively environment friendly technique for successful reactive dyeing of lyocell.

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.

Flexible Fe3O4@Carbon Nanofibers Hierarchically Assembled with MnO2 Particles for High-Performance Supercapacitor Electrodes.

Increasing use of wearable electronic devices have resulted in enhanced demand for highly flexible supercapacitor electrodes with superior electrochemical performance. In this study, flexible composite membranes with electrosprayed MnO2 particles uniformly anchored on Fe3O4 doped electrospun carbon nanofibers (Fe3O4@CNFMn) have been prepared as flexible electrodes for high-performance supercapacitors. The interconnected porous beaded structure ensures free movement of electrolyte within the composite membranes, therefore, the developed supercapacitor electrodes not only offer high specific capacitance of ~306 F/g, but also exhibit good capacitance retention of ~85% after 2000 cycles, which certify that the synthesized electrodes offer high and stable electrochemical performance. Additionally, the supercapacitors fabricated from our developed electrodes well maintain their performance under flexural stress and exhibit a very minute change in specific capacitance even up to 180° bending angle. The developed electrode fabrication strategy integrating electrospinning and electrospray techniques paves new insights into the development of potential functional nanofibrous materials for light weight and flexible wearable supercapacitors.

Pad ultrasonic batch dyeing of causticized lyocell fabric with reactive dyes.

Conventionally, cellulosic fabric dyed with reactive dyes requires significant amount of salt. However, the dyeing of a solvent spun regenerated cellulosic fiber is a critical process. This paper presents the dyeing results of lyocell fabrics dyed with conventional pad batch (CPB) and pad ultrasonic batch (PUB) processes. The dyeing of lyocell fabrics was carried out with two commercial dyes namely Drimarine Blue CL-BR and Ramazol Blue RGB. Dyeing parameters including concentration of sodium hydroxide, sodium carbonate and dwell time were compared for the two processes. The outcomes show that PUB dyed samples offered reasonably higher color yield and dye fixation than CPB dyed samples. A remarkable reduction of 12h in batching time, 18ml/l in NaOH and 05g/l in Na2CO3 quantity was observed for PUB processed samples producing similar results compared to CPB process, making PUB a more economical, productive and an environment friendly process. Color fastness examination witnessed identical results for both PUB and CPB methods. No significant change in surface morphology of PUB processed samples was observed through scanning electron microscope (SEM) analysis.