Laminated Fibrous Membrane Inspired by Polar Bear Pelt for Outdoor Personal Radiation Management

Superhydrophobic Solar-to-Thermal Materials Toward Cutting-Edge Applications

Solar-to-thermal conversion is a direct and effective way to absorb sunlight for heat via the rational design and control of photothermal materials. However, when exposed to water-existed conditions, the conventional solar-to-thermal performance may experience severe degradation owing to the high specific heat capacity of water. To tackle with the challenge, the water-repellent function is introduced to construct superhydrophobic solar-to-thermal materials (SSTMs) for achieving stable heating, and even, for creating new application possibilities under water droplets, sweat, seawater, and ice environments. An in-depth review of cutting-edge research of SSTMs is given, focusing on synergetic functions, typical construction methods, and cutting-edge potentials based on water medium. Moreover, the current challenges and future prospects based on SSTMs are also carefully discussed.

A Scalable and Robust Personal Health Management Textile with Multiple Desired Thermal Functions and Electromagnetic Shielding

The development of functional textiles combining conventional apparel with advanced technologies for personal health management (PHM) has garnered widespread attention. However, the current PHM textiles often achieve multifunctionality by stacking functional modules, leading to poor durability and scalability. Herein, a scalable and robust PHM textile is designed by integrating electrical, radiative, and solar heating, electromagnetic interference (EMI) shielding, and piezoresistive sensing performance onto cotton fabric. This is achieved through an uncomplicated screen-printing process using silver paste. The conductivity of the PHM textile is ≈1.6  ×  104 S m-1, ensuring an electric heating temperature of ≈134 °C with a low voltage of 1.7 V, as well as an EMI shielding effectiveness of ≈56 dB, and human motion monitoring performance. Surprisingly, the radiative/solar heating capability of the PHM textile surpasses that of traditional warm leather. Even after undergoing rigorous physical and chemical treatments, the PHM textile maintains terrific durability. Additionally, the PHM textile possesses maneuverable scalability and comfortable wearability. This innovative work opens up new avenues for the strategic design of PHM textiles and provides an advantageous guarantee of mass production.

Silver nanoparticles coated cellulose-based flexible membrane with excellent UV resistance, high infrared reflection and water resistance for personal thermal management

Designing of a green and multifunctionally integrated cellulose-based flexible wearable material with personal thermoregulation, water and ultraviolet (UV) resistance is essential for the development of personal thermal management and smart textiles. Herein, a hydrophobic silver nanoparticles cellulose-based membrane (H-AgNPs/CEPCM) was prepared through simple solution blending, spin-coating process and chemical vapor modification. The prepared membrane exhibited excellent UV resistance due to the synergistic effect of carbon quantum dots (CQDs) as well as UV-absorbing functional groups. The spin-coated AgNPs layer with high infrared reflectivity has great radiant insulation, and temperature was reduced by 3.4 °C compared with H-CEPCM in indoor environment. Furthermore, the mechanical properties of H-AgNPs/CEPCM were significantly improved by the introduction of amide and ether bonds, as well as a large number of hydrogen bonds. This led to a tensile strength of 23.21 MPa and an elongation at break of 16.57 %, while also providing water resistance. Additionally, the H-AgNPs/CEPCM exhibited outstanding thermal stability and hydrophobicity. This work may provide a feasible and promising strategy for the construction of multifunctional integrated cellulose membrane materials for radiant insulation, outdoor textiles and novel UV protection applications.

Personal Thermal Management by Radiative Cooling and Heating

Maintaining thermal comfort within the human body is crucial for optimal health and overall well-being. By merely broadening the set-point of indoor temperatures, we could significantly slash energy usage in building heating, ventilation, and air-conditioning systems. In recent years, there has been a surge in advancements in personal thermal management (PTM), aiming to regulate heat and moisture transfer within our immediate surroundings, clothing, and skin. The advent of PTM is driven by the rapid development in nano/micro-materials and energy science and engineering. An emerging research area in PTM is personal radiative thermal management (PRTM), which demonstrates immense potential with its high radiative heat transfer efficiency and ease of regulation. However, it is less taken into account in traditional textiles, and there currently lies a gap in our knowledge and understanding of PRTM. In this review, we aim to present a thorough analysis of advanced textile materials and technologies for PRTM. Specifically, we will introduce and discuss the underlying radiation heat transfer mechanisms, fabrication methods of textiles, and various indoor/outdoor applications in light of their different regulation functionalities, including radiative cooling, radiative heating, and dual-mode thermoregulation. Furthermore, we will shine a light on the current hurdles, propose potential strategies, and delve into future technology trends for PRTM with an emphasis on functionalities and applications.

Ag Nanoparticles-Coated Shish-Kebab Superstructure Film for Wearable Heater

Passive and active wearable heaters have received widespread attention due to their efficient utilization of solar energy and all-weather heating capabilities, but the current challenges are their preparation processes being time-consuming and equipment expensive. Herein, a simple and facilitated preparation method for the multifunctional wearable heater was developed, which springs Ag nanoparticles on the shish-kebab superstructure film via deposited melanin-like polydopamine as the adhesive. The light absorption ability of the resultant wearable heater in the visible region can be significantly enhanced by the addition of polydopamine, realizing a highly efficient photothermal conversion ability. Accordingly, it can achieve rapid warming ability whether passive heating (up to 45 °C about 60 s at 100 mW/cm2) or active heating (up to 72 °C about 40 s at 0.6 V), compared to ordinary cotton fabric. In addition, it can realize a 6.3 °C temperature difference with Cotton, showing excellent heat preservation ability. This study demonstrates a simple and low-cost approach for the prepared shish-kebab superstructure-based wearable heaters.

Toward low-emissivity passive heating: a supramolecular-enhanced membrane with warmth retention

Maintaining a reasonably stable body temperature is vital for a variety of human activities in an energy-conservation strategy. However, it is well-known that metal-like materials, utilized as radiative reflectors, severely restrict wearability properties, thus posing a tremendous obstacle in personal thermal management (PTM) systems. Herein, we designed a supramolecular-enhanced membrane (SupraEM) acting as a mid-infrared (MIR) reflector to solve the conundrum of warmth-wearability performance. Benefiting from the low-emissivity of decorating titanium carbide (MXene) and the formation of supramolecular interactions, the prototyped polyvinylidene difluoride&Polyurethane/MXene (PVDF&PU/MXene) SupraEM demonstrated a low-emissivity of 0.246 and reinforced mechanical performance, resulting in an evenly higher temperature retention of 8 °C in comparison to the pristine hybrid membrane counterpart, and compared with a commercial textile that is three times thicker, it also exhibited higher temperature retention of 6.2 °C. This work demonstrates the wearability of decorated MXene without sacrificing its temperature retention, overcoming a major bottleneck that has plagued MXene as a thermoregulatory material for PTM systems.

A Hierarchically Nanofibrous Self-Cleaning Textile for Efficient Personal Thermal Management in Severe Hot and Cold Environments

Climate change has recently caused more and more severe temperatures, inducing a growing demand for personal thermal management at outdoors. However, designing textiles that can achieve personal thermoregulation without energy consumption in severely hot and cold environments remains a huge challenge. Herein, a hierarchically nanofibrous (HNF) textile with improved thermal insulation and radiative thermal management functions is fabricated for efficient personal thermal management in severe temperatures. The textile consists of a radiative cooling layer, an intermediate thermal insulation layer, and a radiative heating layer, wherein the porous lignocellulose aerogel membrane (LCAM) as intermediate layer has low thermal conductivity (0.0366 W·m-1·K-1), ensuring less heat loss in cold weather and blocking external heat in hot weather. The introduction of polydimethylsiloxane (PDMS) increases the thermal emissivity (90.4%) of the radiative cooling layer in the atmospheric window and also endows it with a perfect self-cleaning performance. Solar absorptivity (80.1%) of the radiative heating layer is dramatically increased by adding only 0.05 wt% of carbon nanotubes (CNTs) into polyacrylonitrile. An outdoor test demonstrates that the HNF textile can achieve a temperature drop of 7.2 °C compared with white cotton in a hot environment and can be as high as 12.2 °C warmer than black cotton in a cold environment. In addition, the HNF textile possesses excellent moisture permeability, breathability, and directional perspiration performances, making it promising for personal thermal management in severely hot and cold environments.

Dual-asymmetrically selective interfaces-enhanced poly(lactic acid)-based nanofabric with sweat management and switchable radiative cooling and thermal insulation

All-weather personal thermal regulation has far been challenged by variable environments especially the regulatory failure caused by highly-dense solar radiation, low environmental radiation and the fluctuated epidermal moisture in different seasons. Herein, from the design of interface selectivity, dual-asymmetrically optical and wetting selective polylactic acid-based (PLA) Janus-type nanofabric is proposed to achieve on-demand radiative cooling and heating as well as sweat transportation. Hollow TiO₂ particles are introduced in PLA nanofabric causing high interface scattering (∼99%) and infrared emission (∼91.2%) as well as surface hydrophobicity (CA > 140°). The strictly optical and wetting selectivity help achieve ∼12.8℃ of net cooling effect under > 1500 W/m² of solar power and ∼5℃ of cooling advantage higher than cotton fabric and sweat resistance simultaneously. Contrarily, the semi-embedded Ag nanowires (AgNWs) with high conductivity (0.245 Ω/sq) endows the nanofabric with visible water permeability and excellent interface reflection for thermal radiation from body (>65%) thus causing ∼7℃ of thermal shielding. Through simple interface flipping, synergistical cooling-sweat reducing and warming-sweat resisting can be achieved to satisfy the thermal regulation in all weather. Compared with conventional fabrics, multi-functional Janus-type passive personal thermal management nanofabrics would be of great significance to achieve the personal health maintenance and energy sustainability.

Solar Thermal Textiles for On-Body Radiative Energy Collection Inspired by Polar Animals

Humans use textiles to maintain thermal homeostasis amidst environmental extremes but known textiles have limited thermal windows. There is evidence that polar-dwelling animals have evolved a different mechanism of thermoregulation by using optical polymer materials to achieve an on-body "greenhouse" effect. Here, we design a bilayer textile to mimic these adaptations. Two ultralightweight fabrics with complementary optical functions, a polypropylene visible-transparent insulator and a nylon visible-absorber-infrared-reflector coated with a conjugated polymer, perform the same putative function as polar bear hair and skin, respectively. While retaining familiar textile qualities, these layers suppress dissipation of body heat and maximize radiative absorption of visible light. Under moderate illumination of 130 W/m², the textile achieves a heating effect of +10 °C relative to a typical cotton T-shirt which is 30% heavier. Current approaches to personal radiative heating are limited to absorber/reflector layer optimization alone and fail to reproduce the thermoregulation afforded by the absorber-transmitter structure of polar animal pelts. With increasing pressures to adapt to a rapidly changing climate, our work leverages optical polymers to bridge this gap and evolve the basic function of textiles.

Laminated MXene Foam/Cellulose@LDH Composite Membrane with Efficient EMI Shielding Property for Asymmetric Personal Thermal Management

Facing the increasingly complex and deteriorated environment, people's thermal comfort and health requirements are expanding. Therefore, wearable materials with integrated functions have progressed rapidly due to the fair compatibility for various functions and precise regulation. In this work, a laminated MXene foam/cellulose@LDH composite membrane was fabricated via a facile process consisting of in situ growth, vacuum filtration, and foaming for asymmetrical personal thermal management and electromagnetic interference shielding. In detail, the Zn-Al LDH side shows a high solar reflectance of 0.89 and an infrared emissivity of 0.97 in the atmospheric window, demonstrating the superior radiative cooling property. In contrast, the outstanding radiative warming performance is revealed by the high solar absorption (0.72) and infrared reflectivity (0.55) of the MXene foam. As a result, prominent temperature differences were achieved during the validation test. Compared to the control group, an 18 °C reduction of the Zn-Al LDH side and a 9.6 °C increment of the MXene foam side were observed, bringing out the excellent optical properties and radiative thermal management performances. What is more, due to the outstanding electrical conductivity of MXene, a rapid and prominent temperature rise to 44.2 °C could be expected by applying a low voltage of 1 V to provide active joule warmth. In addition, hydrophobization and the associated stain resistance were explained by the high water contact angles of obtained membranes. The excellent electromagnetic interference shielding performance (43.9 dB) given by the introduction of MXene provides a prospective candidate to replace the common shielding materials. The results, in general, provide a promising strategy for meeting the updating requirements for comfortable living in a world full of potential thermal and health threats.

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.

Wearable and washable light/thermal emitting textiles

Electronic textiles (e-textiles) typically comprise fabric substrates with electronic components capable of heating, sensing, lighting and data storage. In this work, we rationally designed and fabricated anisotropic light/thermal emitting e-textiles with great mechanical stability based on a sandwich-structured tri-electrode device. By coating silver nanowire network/thermal insulation bilayer on fabrics, an anisotropic thermal emitter can be realized for smart heat management. By further covering the emissive film and the top electrode on the bilayer, light emitters with desirable patterns and colors are extracted from the top surface via an alternative current derived electroluminescence. Both the light and thermal emitting functions can be operated simultaneously or separately. Particularly, our textiles exhibit reliable heating and lighting performance in water, revealing excellent waterproof feature and washing stability.

High-Performance Laminated Fabric with Enhanced Photothermal Conversion and Joule Heating Effect for Personal Thermal Management

Multifunctional wearable heaters have attracted much attention owing to their efficient application in personal thermal management. Inspired by the polar bear's thermal management, a laminated fabric with enhanced photothermal conversion, mid-infrared reflection, thermal insulation, and electrical heating performance was developed in this work, which was made of CNT/cellulose aerogel layers, cotton fabrics, and copper nanowire (CuNW)-based conductive network (CNN) layers. The CNN layer made up of highly conductive CuNWs not only exhibits better conductivity to realize the Joule heating effect but also possesses a human mid-infrared reflection property. Moreover, the other side of the cotton fabric was laminated with CNT/cellulose aerogel, which enables the fabric to have a good photothermal conversion ability and thermal insulation performance. The temperature of the laminated fabric could reach to 70 °C within 80 s under 1.8 V; it requires more than 500 s to return to room temperature (28.7 °C). When the light intensity was adjusted to 1000 W/m², the temperature of the laminated fabric was about 74.0 °C after lighting for 280 s. Our work provides a new approach to improving the performance and energy-saving of personal thermal management fabrics.

A SnO2 shell for high environmental stability of Ag nanowires applied for thermal management

Since silver nanowires (AgNWs) show high infrared reflectance many studies present their applicability as thermal management products for various wearable textiles. However, their use for practical purposes is only partially evaluated, without focusing on improving their low atmospheric and liquid stability. This report describes a new approach for the topic and proposes a facile method of Ag nanowire passivation with a SnO2 layer for high environmental stability and retention of high infrared reflectance. The one-step passivation process of AgNWs was carried out in the presence of sodium stannate in an aqueous solution at 100 °C, and resulted in the formation of core/shell Ag/SnO2 nanowires. This study presents the morphological, chemical, and structural properties of Ag/SnO2NWs formed with a 14 nm thick SnO2 shell, consisting of 7 nm rutile-type crystals, covering the silver metallic core. The optical properties of the AgNWs changed significantly after shell formation, and the longitudinal and transverse modes in the surface plasmon resonance spectrum were red shifted as a result of the surrounding media dielectric constant changes. The passivation process protected the AgNWs from decomposition in air for over 4 months, and from dissolution in a KCN solution at concentrations up to 0.1 wt%. Moreover, the report shows the microwave irradiation effect on the shell synthesis and previously synthesised Ag/SnO2NWs. The post-synthesis irradiation, as well as the SnO2 shell obtained by microwave assistance, did not allow long-term stability to be achieved. The microwave-assisted synthesis process was also not fast enough to inhibit the formation of prismatic silver structures from the nanowires. The Ag/SnO2NWs with a shell obtained by a simple hydrolysis process, apart from showing high infra-red reflectance on the para-aramid fabric, are highly environmentally stable. The presented SnO2 shell preparation method can protect the AgNW's surface from dissolution or decomposition and facilitate the designing of durable smart wearable thermal materials for various conditions.