Advanced Functional Fibrous Materials for Enhanced Thermoregulating Performance

Smart and robust phase change cellulose fibers from coaxial wet-spinning of cellulose nanofibril-reinforced paraffin capsules with excellent thermal management

Phase change fibers (PCFs), incorporating with diverse phase change materials (PCMs) such as paraffin wax (PW), have been recognized as one of the effective strategies for fabricate smart thermoregulatory textiles. However, some fatal defects exist in traditional paraffin-cellulose-based PCFs, including the paraffin leakage and the low fiber strength. In this work, we herein propose a facile method to prepare uniform and stable paraffin emulsions stabilized by cellulose nanofibrils (CNFs), followed by a simple coaxial wet spinning to develop smart and robust cellulose-based PCFs for human body temperature management. Benefiting from the CNF-reinforced encapsulation, the stability of paraffin capsules and the compatibility of cellulose and paraffin are indeed promoted, thus allowing the cellulose-based PCF with excellent mechanical strength, leakage prevention, and thermal regulation. As a result, the as-prepared PCF, namely CNF1-PE/PW with optimal 1 wt% CNF1 loading, features a high tensile stress of 10.95 MPa at a strain of 111.2 % and a phase-change enthalpy value of 140.24 J/g with a slight paraffin leakage rate of 0.9 %. Moreover, the corresponding wearable fabric exhibits an excellent thermal storage and release recyclability even after 50 cycles. Therefore, this study provides a new idea for the development of intelligent cellulose-based phase change fiber materials.

Breathable Dual-Mode Leather-Like Nanotextile for Efficient Daytime Radiative Cooling and Heating

Incorporating passive radiative cooling and heating into personal thermal management has attracted tremendous attention. However, most current thermal management materials are usually monofunctional with a narrow temperature regulation range, and lack breathability, softness, and stretchability, resulting in a poor wearer experience and limited application scenarios. Herein, a breathable dual-mode leather-like nanotextile (LNT) with asymmetrical wrinkle photonic microstructures and Janus wettability for highly efficient personal thermal management is developed via a one-step electrospinning technique. The LNT is synthesized by self-bonding a hydrophilic cooling layer with welding fiber networks onto a hydrophobic photothermal layer, constructing bilayer wrinkle structures that offer remarkable optical properties, a wetting gradient, and unique textures. The resultant LNT exhibits efficient cooling capacity (22.0 °C) and heating capacity (22.1 °C) under sunlight, expanding the thermal management zone (28.3 °C wider than typical textiles). Additionally, it possesses favorable breathability, softness, stretchability, and sweat-wicking capability. Actual wearing tests demonstrate that the LNT can provide a comfortable microenvironment for the human body (1.6-8.0 °C cooler and 1.0-7.1 °C warmer than typical textiles) in changing weather conditions. Such a wearable dual-mode LNT presents great potential for personal thermal comfort and opens up new possibilities for all-weather smart clothing.

Highly Stable Polyimide Composite Nanofiber Membranes with Spectrally Selective for Passive Daytime Radiative Cooling

Passive radiative cooling technology without electric consumption is an emerging sustainability technology that plays a key role in advancing sustainable development. However, most radiative cooling materials are vulnerable to outdoor contamination and thermal/UV exposure, which leads to decreased performance. Herein, we report a hierarchically structured polyimide/zinc oxide (PINF/ZnO) composite membrane that integrates sunlight reflectance of 91.4% in the main thermal effect of the solar spectrum (0.78-1.1 μm), the mid-infrared emissivity of 90.0% (8-13 μm), UV shielding performance, thermal resistance, and ideal hydrophobicity. The comprehensive performance enables the composite membrane to yield a temperature drop of ∼9.3 °C, compared to the air temperature, under the peak solar irradiance of ∼800 W m-2. In addition, the temperature drop of as-obtained composite membranes after heating at 200 °C for 6 h in a nitrogen/air atmosphere can be well maintained at ∼9.0 °C, demonstrating their ideal radiative cooling effect in a high-temperature environment. Additionally, the PINF/ZnO composite membrane shows excellent chemical durability after exposure to the outdoor environment. This work provides a new strategy to integrate chemical durability and thermal resistance with radiative cooling, presenting great potential for passive radiative cooling materials toward practical applications in harsh environments.

Gallium-Carbon: A Universal Composite for Sustainable 3D Printing of Integrated Sensor-Heater-Battery Systems in Wearable and Recyclable Electronics

This study presents a novel three-dimensional (3D) printable gallium-carbon black-styrene isoprene styrene block copolymer (Ga-CB-SIS), offering a versatile solution for the rapid fabrication of stretchable and integrated sensor-heater-battery systems in wearable and recyclable electronics. The composite exhibits sinter-free characteristics, allowing for printing on various substrates, including heat-sensitive materials. Unlike traditional conductive inks, the Ga-CB-SIS composite, composed of gallium, carbon black, and styrene isoprene block copolymers, combines electrical conductivity, stretchability, and digital printability. By introducing carbon black as a filler material, the composite achieves promising electromechanical behavior, making it suitable for low-resistance heaters, batteries, and electrical interconnects. The fabrication process involves a simultaneous mixing and ball-milling technique, resulting in a homogeneous composition with a CB/Ga ratio of 4.3%. The Ga-CB-SIS composite showcases remarkable adaptability for digital printing on various substrates. Its self-healing property and efficient recycling technique using a deep eutectic solvent contribute to an environmentally conscious approach to electronic waste, with a high gallium recovery efficiency of ∼98%. The study's innovation extends to applications, presenting a fully digitally printed stretchable Ga-CB-SIS battery integrated with strain sensors and heaters, representing a significant leap in LM-based composites. This multifunctional and sustainable Ga-CB-SIS composite emerges as a key player in the future of wearable electronics, offering integrated circuits with sensing, heating, and energy storage elements.

Wearable Aerogels for Personal Thermal Management and Smart Devices

Extreme climates have become frequent nowadays, causing increased heat stress in human daily life. Personal thermal management (PTM), a technology that controls the human body's microenvironment, has become a promising strategy to address heat stress. While effective in ordinary environments, traditional high-performance fibers, such as ultrafine, porous, highly thermally conductive, and phase change materials, fall short when dealing with harsh conditions or large temperature fluctuations. Aerogels, a third-generation superinsulation material, have garnered extensive attention among researchers for their thermal management applications in building energy conservation, transportation, and aerospace, attributed to their extremely low densities and thermal conductivity. While aerogels have historically faced challenges related to weak mechanical strength and limited secondary processing capacity, recent advancements have witnessed notable progress in the development of wearable aerogels for PTM. This progress underscores their potential applications within extremely harsh environments, serving as self-powered smart devices and sensors. This Review offers a timely overview of wearable aerogels and their PTM applications with a particular focus on their wearability and suitability. Finally, the discussion classifies five types of PTM applications based on aerogel function: thermal insulation, heating, cooling, adaptive regulation (involving thermal insulation, heating, and cooling), and utilization of aerogels as wearable smart devices.

Polyethylene fibers containing directional microchannels for passive radiative cooling

Passive radiative cooling (PRC) that realizes thermal management without consuming any energy has attracted increasing attention. Unfortunately, polymer fibers with radiative cooling function fabricated via a facile, continuous, large-scale and eco-friendly method have been scarcely reported. Herein, polyethylene fibers containing directional microchannels (PFCDM) are facilely fabricated via melt extrusion and water leaching. Interestingly, fabric based on such hydrophobic PFCDM shows high sunlight reflectivity (93.6%), and mid-infrared emissivity (93.9%), endowing it with remarkable PRC performance. Compared with other reported examples, the as-prepared PFDCM fabric has the highest cooling power (i.e., 104.285 W m-2) and temperature drop (i.e., 27.71 °C). Furthermore, decent self-cleaning performance can keep the PFCDM fabric away from contamination and enable it to retain an excellent radiative cooling effect. The method proposed to fabricate PFCDM in this paper will widen the potential application of thermoplastic polyolefins in the field of radiative cooling.

A Polymer Nanocomposite with Strong Full-Spectrum Solar Absorption and Infrared Emission for All-Day Thermal Energy Management and Conversion

Realizing efficient energy utilization from the heat source of the sun and the cold source of outer space is of great significance for addressing the global energy and environmental crisis. Materials with ideal full-spectrum solar absorption and infrared emission are highly desirable for adapting to the continuous weather dynamic throughout the day, nonetheless, their development remains challenging. Here, a polymer nanocomposite with full-spectrum strong solar (280-2500 nm) absorption ranging from 88.8% to 94.8% with an average value of 93.2% and full-spectrum high infrared (8-13 µm) emission ranging from 81.3% to 90.0% with an average value of 84.2%, is reported by melt-processing polypropylene and uniformly dispersed low-loading MXene nanosheets (1.9 vol%). The nanocomposite can achieve daytime photothermal enhancement of ≈50 °C and nighttime radiative cooling of 8 °C. The temperature difference throughout the day ensures all-day uninterrupted thermoelectric generation, yielding a power density output of 1.5 W m-2 (daytime) and 7.9 mW m-2 (nighttime) in real outdoor environment without any additional energy consumption. This work provides an impressive polymer nanocomposite with ideal full-spectrum solar absorption and infrared emission for all-day uninterrupted thermal energy management and conversion.

Rational Design of Stimuli-Responsive Inorganic 2D Materials via Molecular Engineering: Toward Molecule-Programmable Nanoelectronics

The ability of electronic devices to act as switches makes digital information processing possible. Succeeding graphene, emerging inorganic 2D materials (i2DMs) have been identified as alternative 2D materials to harbor a variety of active molecular components to move the current silicon-based semiconductor technology forward to a post-Moore era focused on molecule-based information processing components. In this regard, i2DMs benefits are not only for their prominent physiochemical properties (e.g., the existence of bandgap), but also for their high surface-to-volume ratio rich in reactive sites. Nonetheless, since this field is still in an early stage, having knowledge of both i) the different strategies for molecularly functionalizing the current library of i2DMs, and ii) the different types of active molecular components is a sine qua non condition for a rational design of stimuli-responsive i2DMs capable of performing logical operations at the molecular level. Consequently, this Review provides a comprehensive tutorial for covalently anchoring ad hoc molecular components-as active units triggered by different external inputs-onto pivotal i2DMs to assess their role in the expanding field of molecule-programmable nanoelectronics for electrically monitoring bistable molecular switches. Limitations, challenges, and future perspectives of this emerging field which crosses materials chemistry with computation are critically discussed.

Photothermal Janus fabrics enabling persistent directional sweat-wicking in personal wet-thermal management

Directional sweat-wicking by Janus fabrics has gained substantial attention in promoting personal wet-thermal management for optimal human comfort. During intense physical exercise, excessive sweating can cause the flooding of fabrics and weaken their wicking capabilities once the inner capillary channels are saturated. To address this issue, we develop a photothermal Janus fabric through a facile polydopamine (PDA) deposition followed by single-sided spray-coating of hydrophobic polydimethylsiloxane (PDMS). Such innovative fabrics enable directional sweat-wicking through a Janus structure and persistent removal of excessive sweat by solar-powered evaporation. Under sunlight, our photothermal Janus fabrics exhibit an enhanced evaporation rate, approximately twice compared with that of conventional Janus fabrics (∼1.143 ± 0.027 kg m-2h-1), making them suitable for high sweating rates during vigorous exercise. Furthermore, these fabrics help to maintain the skin temperature within the normal range, preventing hypothermia caused by profuse sweating. In addition, our photothermal Janus fabrics exhibit excellent washing durability even after multiple washing cycles, ensuring prolonged performance and safety.

Sandwich Fibrous PEG Encapsulations for Thermal Energy Storage

Phase change materials (PCMs) textiles have been developed for personal thermal management (PTM) while limited loading amount of PCMs in textiles reduced thermal buffering effect. In this work, we proposed a sandwich fibrous encapsulation to store polyethylene glycol (PEG) with PEG loading amount of 45 wt %, which consisted of polyester (PET) fabrics with hydrophobic coating as protection layers, polyurethane (PU) nanofibrous membranes as barrier layers and PEG-loaded viscose fabric as a PCM-loaded layer. The leakage was totally avoided by controlling weak interfacial adhesion between protection layer and melting PEG. The sandwich fibrous PEG encapsulations had an overall melting enthalpy value ranging from 50 J/g to 78 J/g and melting points ranging from 20 °C to 63 °C by using different PEGs. Besides, introduction of Fe microparticles in PCM-loaded layer enhanced thermal energy storage efficiency. We believe that the sandwich fibrous PEG encapsulation has a great potential in various fields.

Significantly Enhancing Mechanical and Thermal Properties of Cellulose-Based Composites by Adding Small Amounts of Lysozyme-Modified Graphene Nanoplatelets via Forming Strong Double-Cross-Linked Interface Interactions

Thermally conductive cellulose-based composites have great application potential in the thermal management of portable and wearable electronic devices. In this work, cellulose-based composites with excellent mechanical and thermal properties were developed by using lysozyme-modified graphene nanoplatelets (LmGNP), epichlorohydrin (ECH), and hydrolyzed cellulose via forming strong double-cross-linked interface interactions, including the hydrogen bond network generated between LmGNP and cellulose and the chemical cross-link of ECH. As for the composites containing 8 wt % LmGNP, the in-plane thermal conductivity was 3.341 W·m-1K-1, while the tensile stress was 114.60 MPa, which increased by 297.3 and 146.2%, respectively, compared to pure cellulose. Along with the good stability, insulation, and lightweight properties, the fabricated composites have the potential to become a promising heat dissipation material for wearable electronic devices.

Regulating Al2O3/PAN/PEG Nanofiber Membranes with Suitable Phase Change Thermoregulation Features

To address the thermal comfort needs of the human body, the development of personal thermal management textile is critical. Phase change materials (PCMs) have a wide range of applications in thermal management due to their large thermal storage capacity and their isothermal properties during phase change. However, their inherent low thermal conductivity and susceptibility to leakage severely limit their application range. In this study, polyethylene glycol (PEG) was used as the PCM and polyacrylonitrile (PAN) as the polymer backbone, and the thermal conductivity was increased by adding spherical nano-alumina (Al2O3). Utilizing coaxial electrospinning technology, phase-change thermoregulated nanofiber membranes with a core-shell structure were created. The study demonstrates that the membranes perform best in terms of thermal responsiveness and thermoregulation when 5% Al2O3 is added. The prepared nanofiber membranes have a melting enthalpy of 60.05 J·g-1 and retain a high enthalpy after 50 cycles of cold and heat, thus withstanding sudden changes in ambient temperature well. Additionally, the nanofiber membranes have excellent air permeability and high moisture permeability, which can increase wearer comfort. As a result, the constructed coaxial phase change thermoregulated nanofiber membranes can be used as a promising textile for personal thermal management.

The Mechanism by Which Umbrella-Shaped Ratchet Trichomes on the Elaeagnus angustifolia Leaf Surface Collect Water and Reflect Light

Leaves are essential for plants, enabling photosynthesis and transpiration. In arid regions, water availability limits plant growth. Some plants, like Elaeagnus angustifolia, a sandy sub-tree species widely distributed in arid and semi-arid regions, have unique leaf structures to reduce water loss and solar radiation. Here, we describe the leaves of Elaeagnus angustifolia L., with special functioning trichomes. Through leaf submicroscopic structure observation, in situ water collection experiments, photosynthesis measurements, and reflection spectrum analysis, we investigated E. angustifolia leaves, focusing on their functioning trichomes. These trichomes capture water vapor, reflect UV and NIR light, and possess a 3D interface structure composed of 1D and 2D structures. The 1D conical structure captures water droplets, which are then gathered by the radial conical structure and guided towards the stomata through wedge-shaped grooves on the 2D umbrella structure. The trichomes also reflect sunlight, with micropapillae reflecting UV light and the umbrella structure reflecting NIR light. These mechanisms reduce leaf temperature, respiration, and water transpiration, protecting against solar radiation damage. This study provides insights into water collection and light-reflection mechanisms, revealing adaptive strategies of plants with large leaves in arid regions.

Environmentally responsive hydrogel composites for dynamic body thermoregulation

Hydrogel composites exhibiting dynamic thermo-hydro responsive modulation of infrared radiation (IR) in the 5-15 μm range are designed for personalized body thermoregulation. Fabrication of the proposed system relies on the periodic arrangement of submicron-sized spherical fine silica (SiO₂) particles within poly(N-isopropylacrylamide) (PNIPAM)-based hydrogels. The dependence of the SiO₂ particles content on the IR reflection, followed by its modulation in response to any immediate environmental changes are thereby investigated. The addition of 20 wt% of SiO₂ allowed the hydrogel composites to reflect 20% of the IR emitted by the human body at constant temperature (i.e. T = 20 °C) and relative humidity (i.e. RH = 0%). According to Bragg's law, we found that the smaller the distance between the SiO₂ particles, the higher the IR reflection. The IR reflection further increased to a maximum of 42% when the resulting hydrogel composites are subjected to changes in relative humidity (i.e. RH = 60%) and temperature (i.e. T = 35 °C). Thermography is used to map the IR radiation emitted from the hydrogel composites when placed on the skin of the human body, demonstrating that the composite is actually reflecting IR. The latter results are supported by theoretical models that define the IR reflection profile of the resulting hydrogel composites with respect to the silica content, relative humidity and temperature.

Recent Advances in Thermoregulatory Clothing: Materials, Mechanisms, and Perspectives

Personal thermal management (PTM) is a promising approach for maintaining the thermal comfort zone of the human body while minimizing the energy consumption of indoor buildings. Recent studies have reported the development of numerous advanced textiles that enable PTM systems to regulate body temperature and are comfortable to wear. Herein, recent advancements in thermoregulatory clothing for PTM are discussed. These advances in thermoregulatory clothing have focused on enhancing the control of heat dissipation between the skin and the localized environment. We primarily summarize research on advanced clothing that controls the heat dissipation pathways of the human body, such as radiation- and conductance-controlled clothing. Furthermore, adaptive clothing such as dual-mode textiles, which can regulate the microclimate of the human body, as well as responsive textiles that address both thermal performance (warming and/or cooling) and wearability are discussed. Finally, we include a discussion on significant challenges and perspectives in this field, including large-scale production, smart textiles, bioinspired clothing, and AI-assisted clothing. This comprehensive review aims to further the development of sustainably manufactured advanced clothing with superior thermal performance and outstanding wearability for PTM in practical applications.

Anchoring silver nanoparticles on nanofibers by thermal bonding to construct functional surface

Generally, the anchoring of inorganic nanoparticles onto the surface of fibers faces the problem of poor stability, which limits the wide application of nanoparticle functionalized fibers. Herein, nanofibers with shell-core structures were constructed by coaxial electrospinning of two polymers with different melting points (T_m). Polyglycolic acid (PGA, T_m = 225 °C) was employed as the core layer, while polycaprolactone (PCL, T_m = 60 °C) was used as the shell layer. Silver nanoparticles (AgNPs) were electrosprayed on the nanofibers and the shell layer (PCL) was heated and melted to bond the AgNPs, thus realizing a stable AgNP-composited nanofiber for the construction of antibacterial functional surface. By regulating the shell-core flow ratio and the condition for heat treatment, the appropriate thickness of the shell layer was obtained with a flow ratio of 3:1 (PCL:PGA). The optimal composite structure was constructed when the thermal bonding was taken under 80 °C for 5 min. Furthermore, it was found that the composite nanofibers prepared by thermal bonding had better hydrophilicity, mechanical property, and AgNPs bonding stability, and their antibacterial rate against Staphylococcus aureus (S. aureus) reached over 97%. Overall, a facile and universal method for the preparation of nanoparticle-anchored nanofibers was established in this study. The robust nanoparticle-composited nanofibers are promising for applications in optoelectronic devices, electrode materials, and so on.

Aerogels Meet Phase Change Materials: Fundamentals, Advances, and Beyond

Benefiting from the inherent properties of ultralight weight, ultrahigh porosity, ultrahigh specific surface area, adjustable thermal/electrical conductivities, and mechanical flexibility, aerogels are considered ideal supporting alternatives to efficiently encapsulate phase change materials (PCMs) and rationalize phase transformation behaviors. The marriage of versatile aerogels and PCMs is a milestone in pioneering advanced multifunctional composite PCMs. Emerging aerogel-based composite PCMs with high energy storage density are accepted as a cutting-edge thermal energy storage (TES) concept, enabling advanced functionality of PCMs. Considering the lack of a timely and comprehensive review on aerogel-based composite PCMs, herein, we systematically retrospect the state-of-the-art advances of versatile aerogels for high-performance and multifunctional composite PCMs, with particular emphasis on advanced multiple functions, such as acoustic-thermal and solar-thermal-electricity energy conversion strategies, mechanical flexibility, flame retardancy, shape memory, intelligent grippers, and thermal infrared stealth. Emphasis is also given to the versatile roles of different aerogels in composite PCMs and the relationships between their architectures and thermophysical properties. This review also showcases the discovery of an interdisciplinary research field combining aerogels and 3D printing technology, which will contribute to pioneering cutting-edge PCMs. This review aims to arouse wider research interests among interdisciplinary fields and provide insightful guidance for the rational design of advanced multifunctional aerogel-based composite PCMs, thus facilitating the significant breakthroughs in both fundamental research and commercial applications.

Bioinspired Multilayer Structures for Energy-Free Passive Heating and Thermal Regulation in Cold Environments

Passive thermal regulation has attracted increasing interest owing to its zero-energy consumption capacity, which is expected to alleviate current crises in fossil energy and global warming. In this study, a biomimetic multilayer structure (BMS) comprising a silica aerogel, a photothermal conversion material (PTCM), and a phase change material (PCM) layer is designed inspired by the physiological skin structure of polar bears for passive heating with desirable temperature and endurance. The transparent silica aerogel functions as transparent hairs and allows solar entry and prevents heat dissipation; the PTCM, a glass plate coated with black paint, acts as the black skin to convert the incident sunlight into heat; and the PCM composed of n-octadecane microcapsules stores the heat, regulating temperature and increasing endurance. Impressively, outdoor and simulated experiments indicate efficient passive heating (increment of 60 °C) of the BMS in cold environments, and endurance of 157 and 92 min is achieved compared to a single aerogel and PTCM layer, respectively. The uses of the BMS for passive heating of model houses in winter show an increase of 12.1 °C. COMSOL simulation of the BMSs in high latitudes indicates robust heating and endurance performance in a -20 °C weather. The BMS developed in this study exhibits a smart thermal regulation behavior and paves the way for passive heating in remote areas where electricity and fossil energy are unavailable in cold seasons.

A Trimode Thermoregulatory Flexible Fibrous Membrane Designed with Hierarchical Core-Sheath Fiber Structure for Wearable Personal Thermal Management

Advanced textiles designed for personal thermal management contribute to thermoregulation in an individual and energy-saving manner. Textiles incorporated with phase changing materials (PCMs) are capable of bridging the supply and demand for energy by absorbing and releasing latent heat. The integration of solar heating and the Joule heating function supplies multidriving resources, facilitates energy charging and storage, and expands the service time and application scenarios. Herein, we report a fibrous membrane-based textile that was developed by designing the hierarchical core-sheath fiber structure for trimode thermal management. Especially, coaxial electrospinning allows an effective encapsulation of PCMs, with high heat enthalpy density (106.9 J/g), enabling the membrane to buffer drastic temperature changes in the clothing microclimate. The favorable photothermal conversion performance renders the membrane with the high saturated temperature of 70.5 °C (1 sun), benefiting from the synergistic effect of multiple light harvesters. Moreover, a conductive coating endows the composite membrane with an admirable electrothermal conversion performance, reaching a saturated temperature of 73.8 °C (4.2 V). The flexible fibrous membranes with the integrated performance of reversible phase change, multi-source-driven heating, and energy storage present great advantages for all-day, energy-saving, and wearable individual thermal management applications.

Phase-change materials reinforced intelligent paint for efficient daytime radiative cooling

Passive cooling of buildings has become increasingly important for green and low-carbon development, especially in the near decade where daytime radiative cooling technology (DRCT) has drawn attention with big breakthroughs. However, irresistibly importing heat from sunlight and surroundings results in notable temperature rise, thus limiting the cooling effect. Here, we report a radiative paint with latent heat storage capacity to store imported heat by coupling randomly-distributed phase-change materials (PCMs) based microcapsules with acrylic resin to enhance cooling performance. The bifunctional paint shows good performance in selected-suitable phase transition temperature, high enthalpy, high reflectivity in the sunlight region and strong emissivity in the atmospheric window region. The temperature measurements demonstrate that the paint possesses enhanced cooling performance of temperature drop and time buffering effect compared with the pure radiative cooling paint. This work offers the potential to broaden the applications of PCMs and DRCT for energy saving and environment protection.

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Bifunctional paint with radiative cooling and latent heat abilities was developed

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Phase-Change Materials used for isothermal storage of importing heat

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High reflectivity of paint derived from micro size distribution of the microcapsules

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Temperature drop and time buffering effect was achieved by bifunctional paint

Water-Induced Self-Assembly and In Situ Mineralization within Plant Phenolic Glycol-Gel toward Ultrastrong and Multifunctional Thermal Insulating Aerogels

Biopolymer/silica nanocomposite aerogels are highly attractive as thermally insulating materials for prevailing energy-saving engineering but are usually plagued by their lack of mechanical strength and environmental stability. Lignin is an appealing plant phenolic biopolymer due to its natural abundance, high stiffness, water repellency, and thermostability. However, integrating lignin and silica into high-performance 3D hybrid aerogels remains a substantial challenge due to the unstable co-sol process. In diatoms, the silicic acid stabilization prior to the condensation reaction is enhanced by the intervention of biomolecules in noncovalent interactions. Inspired by this mechanism, we herein rationally design an ultrastrong silica-mineralized lignin nanocomposite aerogel (LigSi) with an adjustable multilevel micro/nanostructure and arbitrary machinability through an unusual water-induced self-assembly and in situ mineralization based on ethylene glycol-stabilized lignin/siloxane colloid. The optimized LigSi exhibits an ultrahigh stiffness (a specific modulus of ∼376.3 kN m kg^-1) and can support over 5000 times its own weight without obvious deformation. Moreover, the aerogel demonstrates a combination of outstanding properties, including superior and humidity-tolerant thermal insulation (maintained at ∼0.04 W m^-1 K^-1 under a relative humidity of 33-94%), excellent fire resistance withstanding an ∼1200 °C flame without disintegration, low near-infrared absorption (∼9%), and intrinsic self-cleaning/superhydrophobic performance (158° WCA). These advanced properties make it an ideal thermally insulating material for diversified applications in harsh environments. As a proof of concept, a dual-mode LigSi thermal device was designed to demonstrate the application prospect of combining passive heat-trapping and active heating in the building.

High-Efficiency Electro/Solar-Driven Wearable Heater Tailored by Superelastic Hollow-Porous Polypyrrole/Polyurethane/Zirconium Carbide Fibers for Personal Cold Protection

With the frequent occurrence of extreme weather, using massive energy inputs to maintain the thermal stability of the indoor environment or the human body has become common, and such excessive overuse of nonrenewable energy has created numerous significant problems for modern society. Personal thermal management textiles which can provide the better thermal comfort with less energy consumption than the room heating devices have attracted vast attention in recent years. A polypyrrole/polyurethane/zirconium carbide (PU/PPy/ZrC) fiber with superior electrothermal/photothermal conversion was fabricated via a simple two-step strategy. The surface temperature of PU/PPy/ZrC fibers can reach 51.7 °C under IR lamp irradiation and 55.8 °C at 2 V. In addition, excellent electrical conductivity can be maintained even though the fiber has been stretched to 150%. Due to the porous and hollow structure of the PU/PPy/ZrC fiber, the fiber exhibits outstanding thermal stability and can reach a temperature difference of 5.2 °C. The excellent quick-drying properties allow for fast and complete drying of the material in both modes. Combined with the considerable mechanical properties and hydrophobicity of the PU/PPy/ZrC fiber, it demonstrates the outstanding potential and broad development of this dual-driven fiber for basic research and practical applications in personal cold protection.

Flexible engineering of advanced phase change materials

Liquid phase leakage, intrinsic rigidity, and easy brittle failure are the longstanding bottlenecks of phase change materials (PCMs) for thermal energy storage, which seriously hinder their widespread applications in advanced energy-efficient systems. Emerging flexible composite PCMs that are capable of enduring certain deformation and guaranteeing superior mutual contact with integrated devices are considered as a cutting-edge effective solution. Flexible PCMs-based thermal regulation technology can reallocate thermal energy and regulate the temperature within an optimal range. Currently, tireless efforts are devoted to the development of versatile flexible PCMs-based thermal regulation devices, and a big step forward has been taken. Herein, we systematically outline fabrication techniques, flexibility evaluation strategies, advanced functions and advances of flexible composite PCMs. Furthermore, existing challenges and future perspectives are provided in terms of flexible PCMs-based thermal regulation techniques. This insightful review aims to provide an in-depth understanding and constructive guidance of engineering advanced flexible multifunctional PCMs.

Sandwich Structures Reflecting Thermal Radiation Produced by the Human Body

Far infrared (FIR) textiles are a new category of functional textiles that have presumptive health and well-being functionality and are closely related to human thermo-physiological comfort. FIR exerts strong rotational and vibrational effects at the molecular level, with the potential to be biologically beneficial. In general, after absorbing either sunlight or heat from the human body, FIR textiles are designed to transform the energy into FIR radiation with a wavelength of 4–14 μm and pass it back to the human body. FIR textiles can meet increased demand for light, warm, comfortable, and healthy clothing. The main aim of this research is to describe the procedure for creating the FIR reflective textile layer as part of multilayer textile structures that have enhanced thermal protection. To develop the active FIR reflecting surface, the deposition of copper nanolayer on lightweight polyester nonwoven structure Milife, which has beneficial properties of low fiber diameters, good shape stability and comfort, was used. This FIR reflective layer was used as an active component of sandwiches composed of the outer layer, insulation layer, active layer, and inner layer. The suitable types of individual layers were based on their morphology, air permeability, spectral characteristics in the infra-red region, and thermal properties. Reflectivity, transmittance, and emissivity were evaluated from IR measurements. Human skin thermal behavior and the prediction of radiation from the human body dependent on ambient conditions and metabolic rate are also mentioned. The FIR reflective textile layer created, as part of multilayer textile structures, was observed to have enhanced thermal protection.

A Review of Multiple Scale Fibrous and Composite Systems for Heating Applications

Different types of heating systems have been developed lately, representing a growing interest in both the academic and industrial sectors. Based on the Joule effect, fibrous structures can produce heat once an electrical current is passed, whereby different approaches have been followed. For that purpose, materials with electrical and thermal conductivity have been explored, such as carbon-based nanomaterials, metallic nanostructures, intrinsically conducting polymers, fibers or hybrids. We review the usage of these emerging nanomaterials at the nanoscale and processed up to the macroscale to create heaters. In addition to fibrous systems, the creation of composite systems for electrical and thermal conductivity enhancement has also been highly studied. Different techniques can be used to create thin film heaters or heating textiles, as opposed to the conventional textile technologies. The combination of nanoscale and microscale materials gives the best heating performances, and some applications have already been proven, even though some effort is still needed to reach the industry level.

Knit Architecture for Water-Actuating Woolen Knitwear and Its Personalized Thermal Management

Personalized thermal management using water-actuated woolen knitwear has great potential for smart textile production. However, woolen knitwear exists in a wide range of forms with different derivatives. Manufacturing of smart woolen structures with excellent cooling properties is linked to certain parameters such as changes in loop formation, loop shape, and yarn arrangement upon stimulation of body fluids. To address this issue, textile knit structures with different physical and mechanical properties have been prepared using water-responsive descaled wool fibers and their smart heat and moisture regulation behavior have been investigated and compared to detect the fabric architectural effect on water actuation and cooling performance of woolen garments. The evidence suggests that the technical structure of the fabrics plays a crucial role in pore actuation and fabric cooling performance. The water actuation and thermal management abilities of single jersey were greatly enhanced because of unbalanced structures with lower mechanical stress among the loops and yarns. The experimental data is also in line with the theoretical analysis. Hence, the unbalanced structures control fast heat and mass transfer from the human body, which may offer a promising year-round clothing material to the wearer. This material can have a similar response upon contact with body sweat and humid environments and hence can act as a skinlike fabric. Their possible applications can lie in different fields, such as thermoregulation, functional clothing, sportswear, and medical care.

Recent Trends, Construction and Applications of Smart Textiles and Clothing for Monitoring of Health Activity: A Comprehensive Multidisciplinary Review

In the area of biomedical signal monitoring, wearable electronics represents a dynamically growing field with a significant impact on the market of commercial products of biomedical signal monitoring and acquisition, as well as consumer electronic for vital functions monitoring. Since the electrodes are perceived as one of the most important part of the biomedical signal monitoring, they have been one of the most frequent subjects in the research community. Electronic textile (e-textile), also called smart textile represents a modern trend in the wearable electronics, integrating of functional materials with common clothing with the goal to realize the devices, which include sensors, antennas, energy harvesters and advanced textiles for self-cooling and heating. The area of textile electrodes and e-textile is perceived as a multidisciplinary field, integrating material engineering, chemistry, and biomedical engineering. In this review, we provide a comprehensive view on this area. This multidisciplinary review integrates the e-textile characteristics, materials and manufacturing of the textile electrodes, noise influence on the e-textiles performance, and mainly applications of the textile electrodes for biomedical signal monitoring and acquisition, including pressure sensors, electrocardiography, electromyography, electroencephalography and electrooculography monitoring.

Stimuli-Responsive Shape Changing Commodity Polymer Composites and Bilayers

Commodity polymers are produced in large volumes, providing robust mechanical properties at relatively low costs. The products made from these commodity polymers typically offer only static functionalities. Over the past decade, however, in the scientific literature, stimuli-responsive additives and/or polymer coatings have been introduced to commodity polymers, yielding composites and bilayers that change shape in response to light, temperature, and/or humidity. These stimuli responsive commodity polymers allow the marketing and sales of these otherwise bulk products as "high-end" smart materials for applications spanning from soft actuators to adaptive textiles. This Spotlight on Applications presents an overview of recent intriguing works on how shape changing commodity polymer composite and bilayer actuators based on polyamide 6, poly(ethylene terephthalate), polyethylene, and polypropylene have been fabricated that respond to environmental stimuli and discusses their potential applications.

Thermoconductive, Moisture-Permeable, and Superhydrophobic Nanofibrous Membranes with Interpenetrated Boron Nitride Network for Personal Cooling Fabrics

Space cooling occupies a large portion of total building energy consumption, aggravating the energy crisis and restricting human sustainable development, thus an efficient and energy-saving personal cooling technology is in high demand. Recently, thermally conductive fillers, such as boron nitride (BN), are usually enriched to fibrous materials to construct thermal management textiles. However, these fabrication processes are complex and time-consuming, and the resultant materials fail to transmit moisture and resist liquid water. Herein, we develop a facile and scalable methodology to construct highly thermoconductive breathable superhydrophobic nanofibrous membranes to enhance the thermal management of textiles for personal cooling. The strategy causes boron nitride (BN) to be linked with each other along nanofibers, and thus the membranes contain well interpenetrated BN network and remain porous structure simultaneously, improving their thermal conductivity without sacrificing the moisture permeability. In addition, the membranes possess good resistance to water penetration and intriguing superhydrophobicity due to the synergistic effect of the hydrophobic polymeric matrix and improved roughness. As a consequence, the resultant membranes demonstrate outstanding hybrid active-passive cooling performance with ultrahigh in-plane thermal conductivity of 17.9 W m^-1 K^-1, cross-plane thermal conductivity of 0.29 W m^-1 K^-1, and high water vapor transmission (WVT) rate of 11.6 kg m^-2 day^-1, as well as excellent water repellency with water contact angle of 153° and high hydrostatic pressure of 32 kPa, indicating promising utility for the next generation of cooling fabrics.

Design of Active Interfaces Using Responsive Molecular Components

Responsive interfaces are interfaces that show a defined and reversible change in physical properties in response to external stimuli. Typically, responsive interfaces result from the immobilization of responsive molecular components at the interface that translate a nanoscale signal into a macroscopic effect. Responsive interfaces can also be obtained if the topology of the interface can be reversibly changed using an external stimulus. As the surface of any material is its connection to the environment, responsive interfaces provide opportunities for interactive materials which are not only able to change properties upon demand, but also sense their environment and act autonomously. The application of responsive molecular components at interfaces, however, requires chemical and physical compatibility with the material surface of interest, posing a challenge not least in the retention of the responsive functionality. The state of the art in "active" interfaces which display responsive wettability, permeability, or adhesion is discussed, with a particular emphasis on microscale and nanoscale patterning since patterned interfaces can give rise to unique material properties. Finally, perspectives in the development of responsive interfaces, as well as promising approaches for bypassing the most prominent challenges are discussed.

Advances in photocatalytic self-cleaning, superhydrophobic and electromagnetic interference shielding textile treatments

The use of nanomaterials in textiles provides many new opportunities and advantages for users and manufacturers; however, it comes with some of its downsides and challenges which need to be understood and overcome for enhancing the applicability of these products. This review article discusses the recent progress in developing self-cleaning and conductive textiles as two of the leading research fields of smart textiles. In particular, different aspects of fabricating nanocoatings for photocatalytic self-cleaning, superhydrophobic and electromagnetic interference (EMI) shielding effect will be brought to light. The theoretical concepts, mechanisms, latest fabrication methods along with their potential applications will be discussed. Moreover, the current drawbacks of these fields will be underlined and some recommendations for future research trajectories in terms of performance, current limitations, sustainability and safety will be proposed. This review article provides a comprehensive review on the state-of-the-art achievements in the field, which will be a valuable reference for researchers and decision makers.

Functional Fibers, Composites and Textiles Utilizing Photothermal and Joule Heating

This review focuses on the mechanism of adjusting the thermal environment surrounding the human body via textiles. Recently highlighted technologies for thermal management are based on the photothermal conversion principle and Joule heating for wearable electronics. Recent innovations in this technology are described, with a focus on reports in the last three years and are categorized into three subjects: (1) thermal management technologies of a passive type using light irradiation of the outside environment (photothermal heating), (2) those of an active type employing external electrical circuits (Joule heating), and (3) biomimetic structures. Fibers and textiles from the design of fibers and textiles perspective are also discussed with suggestions for future directions to maximize thermal storage and to minimize heat loss.

Green Production of Regenerated Cellulose/Boron Nitride Nanosheet Textiles for Static and Dynamic Personal Cooling

Personal cooling technology using functional clothing that could provide localized thermal regulation instead of cooling the entire space is regarded as a highly anticipated strategy to not only facilitate thermal comfort and human health but also be energy-saving and low-cost. The challenge is how to endow textiles with prominent cooling effect whenever the wearer is motionless or sportive. In this study, high content of edge-selective hydroxylated boron nitride nanosheets (BNNSs) up to 60 wt % was added into a biodegradable cellulose/alkaline/urea aqueous solution, and then regenerated cellulose (RCF)/BNNS multifilaments were successfully spun in a simple, low-cost, and environmentally friendly process, which was demonstrated to serve as both static and dynamic personal cooling textile. Typically, excellent axial thermal conductivity of RCF/BNNS filament rendered that body-generated heat could directly escape from skin to the outside surface of the textile by means of thermal conduction, achieving a much better static personal cooling result through continuous thermal radiation. Besides, synergistic effect between excellent heat dissipation capability and good hygroscopicity also resulted in much better dynamic cooling effect once the wearer is doing some sports, whose efficiency was even better than commercial hygroscopic textiles such as cotton and RCF.

Corncoblike, Superhydrophobic, and Phase-Changeable Nanofibers for Intelligent Thermoregulating and Water-Repellent Fabrics

The comfort and protection of clothes are critically important for human well-being in life; however, constructing multifunctional fabrics with excellent thermoregulating and water-repellent performance still presents an exciting scientific challenge and a significant technological advancement. Therefore, we report a novel and straightforward methodology to fabricate corncoblike and phase-changeable nanofibers by incorporating n-octadecane phase change capsules (PCCs) for creating water-repellent and thermoregulating nanofibrous membranes. This strategy causes PCC to be uniformly distributed on the nanofibers to form a unique corncoblike structure, preventing the abscission of PCC and the leakage of the phase change ingredient (n-octadecane). Besides, the resultant nanofibrous membranes are endowed with hierarchical roughness, small pore size, and energy storage/release capacity in response to environmental changes. As a consequence, the nanofibrous membranes present prominent water repellence with superhydrophobicity (a water contact angle of 153°) and a high hydrostatic pressure of 84 kPa, robust mechanical properties with a tensile strength of 9.2 MPa, as well as excellent hybrid active-passive thermal regulation with a water vapor transmittance rate of 11.4 kg m^-2 d^-1 and a high phase change enthalpy of 74 J g^-1 after 50 heating/cooling cycles, indicating them to be an exceptional candidate for personal protection and thermal management.

The Design and Manufacture of a Multilayer Low-Temperature Protective Composite Fabric Based on Active Heating Materials and Passive Insulating Materials

Based on active heating materials (the phase change microcapsules (microPCMs)) and passive insulating materials (SiO₂ aerogel), a new-type multilayer low temperature protective composite fabric (MPF) was designed and manufactured to meet the demands of protection and operation in a short time under a low-temperature environment. Results showed that the MPF consisted of three layers including the fabric layer, the microPCM function layer, and the SiO₂ aerogel thermal insulation layer. The differential scanning calorimeter (DSC) results demonstrated that the phase transition enthalpy of the composite was 96.2 J/g during the cooling process. The low-temperature resistance and thermal insulation performance at −50 °C were investigated. The results also demonstrated that the low-temperature resistance time of the MPF was 660 s and the power consumption of the MPFs needed to maintain 37 °C for 10 and 20 min were 629 J and 1872 J, respectively. Compared with the microPCM function layer and the thermal insulation layer, which have the same thickness as the MPF, the low-temperature resistance time of the MPF was prolonged for about 2 and 3 min, respectively. The MPF could provide effective protection of the low-temperature work in a short time and could be applied as potential materials in low-temperature protection.