Superior Mechanical Durability Research Articles

Durable one-component polyurea icephobic coatings with energy-saving performance in electrical heating de-icing

Ice formation and accumulation on the surfaces of aircraft, wind turbines, and boat hulls might result in serious economic losses and catastrophic accidents. The development of a new generation of icephobic surfaces has emerged in recent years for anti-icing. However, insufficient durability of the existing icephobic surfaces remains a significant challenge to their applications. In this study, durable one-component polyurea icephobic coatings (OPICs) with a low ice adhesion strength (∼25.3 kPa) were prepared via a solvent-free method by combining the NCO-terminated prepolymer, latent curing agent, and silicone oil. The chemical structure, surface morphology, wettability, mechanical properties, icephobicity, and durability of the OPICs were studied. The optimized design of OPICs with synergistic icephobic mechanisms endowed them with excellent icephobicity and durability. The superior mechanical durability and chemical stability were revealed by the maintaining icephobicity of OPICs even after 3000 continuous Taber abrasion cycles, as well as 50 icing/de-icing cycles, 72 h of NaOH immersion, and 240 h of neutral salt spray test. The effect of OPICs on minimizing the electric power consumption was further investigated by icing wind tunnel. In comparison to the epoxy primer coated and Al alloy coated airfoil surface, airfoil surface coated by OPIC-30 was found to achieve about 43.7 % and 43.9 % energy savings in the keeping entire airfoil surface ice-free, respectively. The one-component polyurea icephobic coatings have great prospects for practical applications that require long-term anti-icing properties.

Femtosecond laser writing of durable open microfluidic channels via a mode-switchable strategy

Open microfluidic systems offer significant advantages, including the elimination of external pumps and facilitating fluid access at any point along the channel. However, their deployment in harsh environments is commonly compromised due to the delicate nature of hydrophilic chemical coatings and the vulnerability of open microchannels to clogging and contamination. Here, a bioinspired, demand-responsive mode-switchable strategy is proposed to enhance the mechanical durability of open microfluidic systems. Specifically, under harsh conditions or when long-term storage is necessary, this strategy allows the open microfluidic device to transition to a protective mode simply through releasing the strain, thereby preserving the integrity of the structure and hydrophilic coatings. The stretched open microfluidic mode enables spontaneous liquid spreading along a hydrophilic microchannel scribed by femtosecond laser. This mode-switchable strategy provides the open microfluidic device with robustness to maintain spontaneous liquid flow, even under severe testing conditions such as 2000 cycles of cotton swab rubbing, sand impact, sandpaper abrasion, tape peeling, twisting, and finger rubbing. A proof-of-concept application involving blood type analysis on this mode-switchable open microfluidic device showcases its superior mechanical durability under severe environmental conditions. The proposed strategy paves the way for the broader use of open microfluidic devices in various practical applications.

Unlocking Power: Impact of Physical and Mechanical Properties of Biomass Wood Pellets on Energy Release and Carbon Emissions in Power Sector

Abstract This study investigates the physical and mechanical properties of 12 biomass wood pellet samples utilised in a power generation, focusing on their implications for energy release and carbon emissions during combustion. Through comprehensive analysis involving bulk density measurements, compression tests, moisture analysis, calorimetry and controlled burning experiments, significant correlations among key properties are identified. Pellets with densities above 1100 kg/m3 demonstrate superior mechanical durability and strength, achieving maximum strengths of 0.6 to 0.8 kN with durability exceeding 99.4%. Optimal moisture content, typically between 6 and 7% is crucial for maximising density, bulk density, mechanical durability and fracture resistance, ensuring robust pellet structure and performance. The research underscores the impact of pellet dimensions, highlighting those longer lengths, > 12 mm enhance durability, while larger diameters > 8 mm exhibit reduced durability. Elemental analysis focusing on calcium, silicon and potassium plays a critical role in predicting and managing combustion system fouling, potentially reducing operational costs. Moreover, the study emphasises the significant influence of oxygen levels during combustion on CO2 emissions, achieving optimal results with moisture content in the 7–8% range for maximum higher heating value (HHV). The moisture content in the 14–15% range represents the lowest CO2 emission. The findings underscore the intricacy of the system and the interplay of parameters with one another. In accordance with the priority of each application, the selection of parameters warrants careful consideration. Graphical Abstract

Polyphosphazene with excellent superhydrophobicity, electrical insulation, flame-retardancy, and mechanical durability for composite insulators

Composite insulator is an important component of the power system which has high requirements for insulating properties, hydrophobicity, long-term reliability, and safety. Aiming to improve the comprehensive performance of composite insulators, we propose a novel composite based on polyphosphazene matrix and inorganic fillers including h-BN, SiO2 and aramid pulp (AF-p). By the synergistic effect of the optimized chemical structure of polyphosphazene and modification by multi-scale hydrophobic electrical insulation fillers, the poly(difluoroalkoxy)phosphazenes (PDFP) composite presents enhanced hydrophobicity with the static water contact angle (WCA) up to 154° and rolling angle (RA) as low as 8°. Benefiting from the multiscale roughness constructed by multi-fillers, the PDFP composite exhibits superior mechanical durability. The contact angle of the sample still exceeds 150° after abrasion by sandpaper (800#) for 1000 cm. Meanwhile, with the addition of hybrid insulation fillers, the Weibull breakdown strength of PDFP/30h-BN/10SiO2-200/6AF-p is improved by 76 % compared to PDFP. Besides, the unique elemental composition of PDFP endows the PDFP composite with excellent flame retardancy with a 55 % limiting oxygen index and V-0 of the UL-94 grade, which guarantees safety for insulator applications. The results confirm the great potential of polyphosphazene for composite insulators.

Nanosecond laser-assisted fabrication of Ti6Al4V surfaces with gradient wettability and robust cross-linked microstructures

Abstract Surfaces with gradient wettability outperform singular superhydrophobic surfaces in terms of self-cleaning efficiency, anti-contamination properties, and fluid manipulation. These attributes offer extensive application potential across various industrial and scientific domains. This study introduces and employs nanosecond pulsed laser ablation to create wettability gradient surfaces on Ti6Al4V alloys, featuring robust cross-linked frame microstructures. Experimental results demonstrate that by varying the ridge width (w), associated with the liquid-solid contact fraction, we can achieve varying wettability and mechanical durability in these cross-linked frame microstructures. Wettability tests indicate static contact angles ranging from 150.7° to 105.45°. Furthermore, the sandpaper linear abrasion test illustrates a decrease in material wear rate with an increase in w. Under similar test conditions, the proposed surfaces demonstrate superior mechanical durability compared to two other prevalent wettability surface structures. The proposed surfaces, efficiently and eco-friendly produced through nanosecond laser fabrication, hold tremendous potential for diverse applications.

Designing MOFs/CuCo-LDHs hybrid-based superhydrophobic sponge for speedy eliminating microplastics, dyes, and oils from high-salinity water

It is urgent to develop effective materials to decontaminate wastewater owing to water scarcity in the whole world. In this study, we successfully fabricated a superhydrophobic and superoleophilic MOFs/LDHs based-functional sponge (OMCTS/ZIF-67/CuCo-LDHs@Sponge) with large specific surface area and high porosity for the first time through a two-step co-precipitation method and surface modification of polysiloxane. The polydopamine (PDA) molecules not only greatly improved the adhesion between coatings and substrate, but also enhanced growth of MOFs and LDHs structure. The in-situ growth of hexahedron ZIF-67 particles on multiple layered CuCo-LDHs sphere formed heterojunction, which significantly increased adsorption sites, specific area, and porosity and also solved the aggregation problem of powder MOFs. The CuCo-LDHs with large surface area was beneficial to ZIF-67 growth owing to same Co2+connection. The developed superhydrophobic sponge not only quickly and selectively absorbed various microplastics (MPs, as high as 500 mg/mL), dyes (C0 = 40 mg/L, removal rate of 99.6 %), and emulsified oils from high-salinity water with high capacity (e.g. 85 mg/g for PP-2000, 94 mg/g for PS-100, and 93 mg/g for PE-2000), but also exhibited outstanding synchronous decontamination capability for coexisting pollutants through multi-molecular synergistic mechanism and multiple adsorption forces (grasping force, strong capillarity, electrostatic interaction, hydrogen bonds, π-π interactions, p-π conjugation interaction. Van der Waals forces). The coated sponge showed superior mechanical durability, which still maintained separation ability above 98 % after repeated adsorption of MPs for 40 cycles. The adsorption mechanism was detailly investigated through theoretical simulation of adsorption energy. This coated sponge was destined to show broad and useful applications in water purification field.

Robust Low-Friction and Low-Wear TiNbMoTaCr High-Entropy Film Enabled by Periodically Inserting Curved MoS2 Sheets.

The well-known integration of physical, chemical, and mechanical properties enables high-entropy alloys (HEAs) to be applied in various fields; however, refractory HEAs are brittle and susceptible to abrasive wear at high coefficients of friction (COF), resulting in insufficient mechanical durability against abrasion. Herein, curved MoS2 nanosheets are periodically introduced into the TiNbMoTaCr film for triggering the self-assembly mixed metal oxides @MoS2 nanoscrolls, which contain hard mixed metal oxides cores and the low-shearing lubricant MoS2 shells, during the friction in the air environment; such mixed metal oxides@MoS2 nanoscrolls in the friction interfaces can contribute to the robust low friction and low wear. Compared to the pure TiNbMoTaCr film (with high COF of ∼0.78, low abrasive durability identified by worn-out event), the periodic incorporation of 10 nm thickness curved MoS2 sheets can successfully achieve a low COF of ∼0.08 and low wear rate of ∼9.561 × 10-8 mm3/ Nm, much lower than the pure MoS2 film (COF = ∼ 0.21, wear rate = ∼ 1.03 × 10-6 mm3/ Nm). Such superior tribological properties originate from the cooperative interaction of TiNbMoTaCr nanolayers and curved MoS2 nanosheets, accompanied by the self-assembly of mixed metal oxides@MoS2 nanoscrolls. In these nanoscrolls, TiNbMoTaCr can act as an 'air-absorbing agent' to form high-loading mixed metal oxide cores and serve as an 'oxygen sacrificer,' preventing the low-shearing lubricant curved MoS2 nanosheets from oxidation. In addition, even with the soft MoS2, the hardness of the TiNbMoTaCr/MoS2 nanomultilayers can still be well maintained and increased above the calculated values by mixing law, further favoring superior mechanical durability. The synergetic effect of TiNbMoTaCr and curved MoS2 nanosheets during the friction in air can provide a route to design HEA films with enhanced tribological properties for better mechanical durability and broader application prospects.

High stability visible-light photoresponse of flexible heterostructures based on LaCoO3 epitaxial films

The research of high-speed photodetector and high-speed optical receiver garners significant attention due to their indispensable properties in many fields including high-temperature event monitoring, security, and ad hoc network wireless communication. Inorganic perovskite oxides LaCoO3 films showcase an extensive prospect in this area owing to their remarkable photoconductive effect. Up to present, however, LaCoO3 films are mostly grown on rigid instead of flexible substrates, greatly limiting their applications to wearable optoelectronic sensors. In this work, we fabricated some flexible LaCoO3 thin films to study their photoresponse. By inserting SrTiO3 and BaTiO3 as buffer layers, we find that LaCoO3 thin films could epitaxially grow on the fluorphlogopite surface and show a stable photoresponse to visible-light. Nevertheless, we also found that the epitaxial strain and the content of surface-adsorbed oxygen could impact the photoconductivity. The mechanical strain generated by bending the fluorphlogopite substrate has been confirmed to has a tunable effect on the photoresponse. Moreover, with the fatigue tests of 105 bending cycles, the flexible LaCoO3 thin films maintain a good photoresponse without any essentially weakening, proving a superior mechanical durability and stability. This work not only indicates the feasibility of the LaCoO3 films applied for flexible photodetectors but also opens a path for other perovskite films applications for flexible substrate.

Anti-friction gold-based stretchable electronics enabled by interfacial diffusion-induced cohesion

Stretchable electronics that prevalently adopt chemically inert metals as sensing layers and interconnect wires have enabled high-fidelity signal acquisition for on-skin applications. However, the weak interfacial interaction between inert metals and elastomers limit the tolerance of the device to external friction interferences. Here, we report an interfacial diffusion-induced cohesion strategy that utilizes hydrophilic polyurethane to wet gold (Au) grains and render them wrapped by strong hydrogen bonding, resulting in a high interfacial binding strength of 1017.6 N/m. By further constructing a nanoscale rough configuration of the polyurethane (RPU), the binding strength of Au-RPU device increases to 1243.4 N/m, which is 100 and 4 times higher than that of conventional polydimethylsiloxane and styrene-ethylene-butylene-styrene-based devices, respectively. The stretchable Au-RPU device can remain good electrical conductivity after 1022 frictions at 130 kPa pressure, and reliably record high-fidelity electrophysiological signals. Furthermore, an anti-friction pressure sensor array is constructed based on Au-RPU interconnect wires, demonstrating a superior mechanical durability for concentrated large pressure acquisition. This chemical modification-free approach of interfacial strengthening for chemically inert metal-based stretchable electronics is promising for three-dimensional integration and on-chip interconnection.

A Robust Biomimetic Superhydrophobic Coating with Superior Mechanical Durability and Chemical Stability for Inner Pipeline Protection.

Durable superhydrophobic anti-erosion/anticorrosion coatings are highly demanded across various applications. However, achieving coatings with exceptional superhydrophobicity, mechanical strength, and corrosion resistance remains a grand challenge. Herein, a robust microstructure coating, inspired by the cylindrical structures situated on the surface of conch shell, for mitigating erosion and corrosion damages in gas transportation pipelines is reported. Specifically, citric acid monohydrate as a pore-forming agent is leveraged to create a porous structure between layers, effectively buffering the impact on the surface. As a result, the coating demonstrates remarkable wear resistance and water repellency. Importantly, even after abrasion by sandpaper and an erosion loop test, the resulting superhydrophobic surfaces retain the water repellency. The design strategy offers a promising route to manufacturing multifunctional materials with desired features and structural complexities, thereby enabling effective self-cleaning and antifouling abilities in harsh operating environments for an array of applications, including self-cleaning windows, antifouling coatings for medical devices, and anti-erosion/anticorrosion protection, among other areas.

Antibacterial highly sensitive eco-friendly wearable piezoresistive sensor for monitoring multiple physiological parameters

Recent progress in wearable biomedical devices has made real-time monitoring possible through non-invasive wearable strain sensors, which can transform physical or biological signals into electrical responses. This work has fabricated multifunctional wearable strain sensors by coating composites (SiE-µG) of electrochemically exfoliated micro-sized multi-layer graphene flakes (µG) and Silicone elastomer (SiE) onto stretchable textile-based orthopedic bandage having ZnO adhesive (SiE-µG@Bandage). The composite coated textile sensors exhibited a remarkable sensitivity of 18330, large stretchability of 35%, superior mechanical durability of 50000 cycles, minute detection limit of 0.04% strain, and fast response time of 400 and recovery time 900 ms. The SiE-µG@Bandage also showed antibacterial properties against Escherichia coli (E. coli) bacteria. Additionally, zinc oxide-based skin-friendly and non-toxic adhesive on the backside of the bandage allowed stable and conformal attachment with the skin. Owing to the above merits, the sensors have shown applicability in real-time monitoring of various physical activities, physiological signals, joint movements, yoga postures, and meditation. Furthermore, the relevance of the sensors in the man-machine interaction has been demonstrated via real-time monitoring of traffic signals by finger movements. Moreover, the exceptional performance and specific features of the SiE-µG@Bandage sensors have enabled their application as electronics skins in health care and preventive care.

Boosting the Output Performance of the MoS2 Monolayer-Based Piezoelectric Nanogenerator by Artificial Dual Strain Concentration.

Piezoelectric nanogenerators (PENGs) with molybdenum disulfide (MoS2) monolayers have been intensively studied owing to their superior mechanical durability and stability. However, the limited output performance resulting from a small active area and low strain levels continues to pose a significant challenge that should be overcome. Herein, we report a novel strategy for the epoch-making output performance of a PENG with a MoS2 monolayer by adopting the additive strain concentration concept. The simulation study indicates that strain in the MoS2 monolayer can be initially augmented by the wavy structure resulting from the prestretched poly(dimethylsiloxane) (PDMS) and is further increased through flexural deformation (i.e., bending). Based on these studies, we have developed concentrated strain-applied PENGs with MoS2 monolayers. The wavy structures effectively applied strain to the MoS2 monolayer and generated a piezoelectric output voltage and current of around 580 mV and 47.5 nA, respectively. Our innovative approach to enhancing the performance of PENGs with MoS2 monolayers through the artificial dual strain concept has led to groundbreaking results, achieving the highest recorded output voltage and current for PENGs based on two-dimensional (2D) materials, which provides unique opportunities for the 2D-based energy harvesting field and structural insight into how to improve the net strain on 2D materials.

Multifunctional MOF-Derived Au, Co-Doped Porous Carbon Electrode for a Wearable Sweat Energy Harvesting-Storage Hybrid System.

As an efficient alternative for harnessing the energy from human's biofluid, a wearable energy harvesting-storage hybrid supercapacitor-biofuel cell (SC-BFC) microfluidic system is established with one multifunctional electrode. The electrode integrates metal-organic framework (MOF) derived carbon nanoarrays with embedded Au, Co nanoparticles on a flexible substrate, and is used for the symmetric supercapacitor as well as the enzyme nanocarriers of the biofuel cell. The electrochemical performance of the proposed electrode is evaluated, and the corresponding working mechanism is studied in depth according to the cyclic voltammetry and density functional theory calculation. The multiplexed microfluidic system is designed to pump and store natural sweat to maintain the continuous biofuel supply in the hybrid SC-BFC system. The biofuel cell module harvests electricity from lactate in sweat, and the symmetric supercapacitor module accommodates the bioelectricity for subsequent utilization. A numerical model is developed to validate the normal operation in poor and rich sweat under variable situations for the microfluidic system. One single SC-BFC unit can be self-charged to ≈0.8V with superior mechanical durability in on-body testing, as well as energy and power values of 7.2 mJ and 80.3 µW, respectively. It illustrates the promising scenery of energy harvesting-storage hybrid microfluidic system.

Urchin-like fluorinated covalent organic frameworks decorated fabric for effective self-cleaning and versatile oil/water separation

Oil contamination and industrial organic pollutants emission have been a serious problem affecting the ecological and residential environment. Membrane-based separation shows great application prospect due to its low-cost, environmental-friendly and easy operation. Therefore, the development of efficient oil-water separation membranes is highly desirable. Herein, a fabric filter with superwettability was prepared by coating urchin-like fluorinated covalent organic frameworks (COFs) on fabric, which was well utilized in filtering immiscible oil-water mixture and surfactant-stabilized water-in-oil emulsion driven only by gravity for the first time. The as-prepared COF fabric filter (defined as fabric@u-FCOF) possessed many outstanding properties, including superhydrophobicity with the water contact angle of approximately 151.6°, satisfactory resistance for alkaline, acidic and saline environments, as well as superior mechanical durability under harsh conditions. Because of the super-micropore of fabric@u-FCOF and the nanopore in the COF coating, the obtained fabric@u-FCOF exhibited excellent performances in terms of separation efficiency and permeability, in which the oil flux was up to 16964 L·m−1·h−2 and separation efficiency for the mixed o-dichlorobenzene/water was higher than 99.4%. In addition, the fabric@u-FCOF also showed excellent self-cleaning performance due to the micro/nano hierarchical structure of its surface. These excellent properties make it an ideal candidate for applications of oil/water separation and water purification.

Covalent Bonding Homo-All-in-One Configuration Enables a Flexible Supercapacitor with Superior Mechanical Durability Exceeding 50 000 Cyclic Deformations

All-in-one configured supercapacitor holds great promise in addressing cyclic deformation-induced relative displacement and delamination among electrode/electrolyte/electrode faced by the conventional laminated supercapacitor, but its interfacial interactions among heterogeneous electrode/electrolyte/electrode only depend on weak secondary or physical bonds, leading to insufficient mechanical durability. Herein, a concept of covalent bonding homo-all-in-one configuration is proposed to construct strong covalent bonding interfaces among electrode/electrolyte/electrode comprising homomatrix polymer PVA through simultaneous chemical cross-linking of the homomatrixes and interfaces, thereby achieving mechanically durable homo-all-in-one supercapacitors (cPMP/cPVA/cPMP HSCs). Based on the adjustment in cross-linking time, seamlessly integrated interfaces form in the cPMP/cPVA/cPMP HSCs, which achieve high mechanical properties, remarkable interfacial bonding strength, and low interfacial charge transfer resistance. In sharp contrast to conventional laminated supercapacitors, the cPMP/cPVA/cPMP HSCs deliver superior areal capacitance of 268.8 mF cm–2 at 5 mV s–1 and unexpected cyclic stability with capacitance retention of 104% after 20 000 charge–discharge cycles. It is highlighted that the cPMP/cPVA/cPMP HSCs reach an unprecedented level of mechanical durability with capacitance retention of 103% and 101% exceeding 50 000 bending and twisting cycles, respectively. Furthermore, the cPMP/cPVA/cPMP HSCs are demonstrated to light up a red LED bulb under flat, bending, twisting, and even folding conditions. Those findings are intended to lead to an advanced design trend for the development of covalent bonding homo-all-in-one configured supercapacitors toward flexible and wearable electronic applications.

Hydrogel Electrolyte with High Tolerance to a Wide Spectrum of pHs and Compressive Energy Storage Devices Based on It.

Normally, hydrogel electrolytes widely used in flexible energy storage devices have limited tolerance to different pHs. Most gel electrolytes will lose their compressible capability when the adaptable pH is changed. Herein, a poly(acrylamide3 -co-(sulfobetaine methacrylate)1 )@polyacrylamide (P(A3 -co-S1 )@PAM) hydrogel electrolyte equipped with a dual crosslinking network (DN) is successfully fabricated, which exhibits excellent tolerance to any pHs, endowing various energy storage devices including batteries and supercapacitors with superior mechanical durability. The batteries with mild and alkaline P(A3 -co-S1 )@PAM electrolytes display superior stability (over 3000 cycles). Additionally, a Zn||MnO2 battery based on the P(A3 -co-S1 )@PAM hydrogel electrolyte (mild) under 50% compression strain also shows excellent charge-discharge stability and high capacity at 152.4 mAh g-1 after 600 cycles. The strong reversible hydrogen bonds and electrostatic forces originating from zwitterionic structures of poly(sulfobetaine methacrylate) play an important role in dissipating and dispersing energy imposed abruptly. Meanwhile, the zwitterionic structure and intermolecular NH⋯OC hydrogen bonds of the hydrogel lead to the property of acid resistance and alkali resistance. The tough and robust covalent crosslinking bonds and the tight arrangement of DN polymer chains enable the hydrogel electrolytes to recover their initial shape fast once unloading.

Biomimetic laminated basalt fiber-reinforced composite with sinusoidally architected helicoidal structure integrating superior mechanical properties and microwave-transmissibility

High-efficient microwave-transmissibility, mechanical durability, and lightweight are in significant demand for wireless communication components. Unfortunately, conventional materials can hardly meet the requirements for emerging radio-frequency (RF) devices so far. Herein, inspired by the sinusoidally architected helicoidal structure of mantis shrimp's dactyl club, a biomimetic laminated basalt fiber-reinforced composite (BL-BFRC) is designed and manufactured through a method combining linear helicoidal layup and hot press forming. Remarkably, the flexural strength and flexural modulus of BL-BFRC are 259.71 MPa and 22.61 GPa, which increase by 28.4% and 36.9% over those of conventional BFRC (202.27 MPa and 16.52 GPa). In addition, BL-BFRC exhibits a dielectric constant of 2.2858 and a loss tangent of 1.55 × 10−3, which are much lower than those of conventional BFRC (3.6459 and 9.73 × 10−3). Accordingly, the microwave-transmissibility increases from 93.53% (conventional BFRC) to 98.34% (BL-BFRC). In fact, the superior mechanical durability of BL-BFRC is mainly attributed to the crack deflection of helicoidal structure and stress dissipation of sinusoidal morphology. And the efficient microwave-transmissibility benefits from dielectric transition effect on non-smooth sinusoidal surface. This work uniquely combines the features of high-efficient microwave-transmissibility and mechanical durability into RF devices and would enable a broad range of wireless communication applications.

Beetle-Inspired Dual-Directional Janus Pumps with Interfacial Asymmetric Wettability for Enhancing Fog Harvesting.

Fog-harvesting devices (FHDs) have been widely explored and applied to alleviate the shortage of fresh water. However, during the fog collection process, how to maintain a balance between fog capture and water removal behaviors to enhance the water collection rate still remains a challenge. Herein, inspired by the Stenocara beetle, we combined a beetle-like Janus surface and the conventional cross-sectional Janus structure together, developed a simple spray-and-dry strategy to obtain three types of biomimetic asymmetric meshes, and explored the working modes for atmospheric fog collection. The surface wettability could be carefully controlled, and various asymmetric meshes with different water transportation behaviors were obtained. Through a detailed study of the fog collection process, we concluded that there existed three main working modes: Janus mode, hybrid mode, and Janus and hybrid mode. It was noted that the dual-directional Janus pump with the Janus and hybrid working mode balanced the fog capture and water removal ability and exhibited the highest water collection rate of 2478.73 mg m-2 h-1, which was 2.61 times more than that of the corresponding superhydrophilic mesh. Furthermore, the prepared dual-directional Janus pump showed superior mechanical durability and antibacterial ability. In general, this work was considered instrumental in the reasonable design of biomimetic asymmetric meshes and could provide references for efficient atmospheric fog harvesting.

Rational fabrication of fluorine-free, superhydrophobic, durable surface by one-step spray method

The role of superhydrophobic coating in metal anti-corrosion, oil leakage treatment, waterproofing and antifouling cannot be overstated, yet the application of conventional superhydrophobic coatings is limited due to their toxicity, poor mechanical stability, and high cost. Herein we report our design on an eco-friendly wax-derived organic-based superhydrophobic coating based on self-designed sol and eco-friendly wax and integrated the spray coating technique. The W-GPAC coating exhibits superhydrophobicity (Contact Angle: 170.6°, Sliding Angle: 5.3°) with a glass substrate. It should be noted that the coating could preserve excellent superhydrophobic property in water spray impact test (Contact Angle:160° after 500 water impact cycles), linear abrasion test(Contact Angle:160° after 120 cm linear abrasion), and acid-base durability test (Contact Angle: greater than 165° after immersion in the acidic or alkaline environment for 600 min). In addition, the coating maintains outstanding adhesion with various substrates even at freezing treatment. The superior performance of the coating comes from the folded structure formed by the drying of GPAC sol which is formed by the dense siloxane crosslinking network of GPAC sol and long-chain silane on the coating surface. Taken together, the W-GPAC superhydrophobic coating enjoys low manufacturing cost, easy degradability, and no secondary pollution, and can be applied to almost commonly used substrates with superior mechanical durability, which could provide alternative solution for superhydrophobic application.

A large‐scalable spraying‐spinning process for multifunctional electronic yarns

AbstractElectronic fibers/textiles have great potential for applications in smart wearables due to their excellent flexibility, air permeability, and wearing comfort. However, it is still challenging to produce reliable electronic textiles at low cost and in a large scale. Herein, we report a spraying‐spinning process for fabricating electronic yarns with excellent stability and durability. Cotton sliver, which is the raw material for spinning conventional cotton yarns, was spray coated with carbon nanotubes (CNTs) and spun on an Ag@nylon yarn, forming a sheath‐core structured CNT@cotton‐Ag@nylon yarn (CCAY). The process is continuous, large‐scalable, applicable to other raw fiber materials and compatible with traditional textile processes. The as‐prepared CCAY showed superior mechanical durability, washability, and conductivity to typical surface coated yarns. It can be easily processed or integrated into textiles through weaving, knitting, sewing, and embroidering. We systematically studied the electromechanical, electro‐thermal, and photothermal performance of CCAY based yarns/fabrics, demonstrating its versatile applications in smart textiles. In addition, CCAY can be further equipped with other features, such as electro‐thermochromic functions, pH sensing and flame resistant abilities. Considering the large‐scalability, versatility, and low‐cost, we foresee that this spraying‐spinning process for electronic yarns may play important roles in the development of practical smart fibers/textiles.