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.

While providing electrical energy for human society, power equipment also consumes electricity and generate heat. Cooling equipment consumes a significant amount of electricity, further increasing energy consumption and load on the power grid. Therefore, there is an urgent need to develop low-energy and sustainable cooling technologies for power equipment. In this study, a hybrid passive cooling composite designed to enhance heat dissipation for heavy-load power equipment is introduced. Specifically, the composite material achieves outstanding radiative cooling performance with an average solar reflectance of up to 0.98, while its excellent atmospheric water harvesting performance ensures high evaporation cooling power without the need for manual water replenishment. As a result, the composite effectively lowers the temperature of outdoor heavy-load power equipment (e.g., transformers) by 25.3 °C. The excellent heat dissipation properties of the composite make it a powerful tool in safeguarding electrical systems.

This study presents a comprehensive investigation into a 3D simulation of magnetorheological (MR) conical bearings, focusing on considering viscous dissipation using the conjugated heat transfer approach. The behavior of MR fluids is expressed through the utilization of the Bingham-Papanastasiou constitutive equation. Notably, this study considers variations in viscosity and yield stress as functions of both magnetic field intensity and temperature. The study utilizes a multidisciplinary approach, encompassing fluid dynamics, magnetism, and heat transfer, to model and analyze the behavior of MR fluids within conical bearing geometries. The governing equations containing Cauchy momentum, energy, and Maxwell equations are solved using the finite element method. This research delves into the impacts of viscous dissipation on the functional and characteristic attributes of conical bearings. The energy equations in solid and fluid domains and extended considerations to the plug region within viscous dissipation are specifically addressed. Extensive validation is performed through a comparative analysis involving experimental, numerical, and analytical studies to ensure the validity of results. The results reveal the substantial impact of temperature on both the characteristics and functionality of magnetorheological conical bearings.

Manipulation of infrared emissivity, which is closely related to surface structure and optical parameters of materials, is a crucial approach for realizing dynamic thermal management. In this study, we design a metamaterial consisting of an array of aluminum disks embedded on a surface of a stretchable elastomeric substrate. Mechanical stretching-induced deformation allows dynamic modification of the surface structure and equivalent optical parameters, thus enabling dynamic control of the emissivity. By utilizing the elastomer polydimethylsiloxane (PDMS) as the substrate, the microstructure interdisk gap can be altered by stretching the PDMS. Through theoretical calculations, the plausibility of this approach is explained by the excitation of plasmon resonance and the variation in the exposed area of highly absorbent PDMS, and the optimal structures for tuning the infrared emissivity are revealed to be 6 μm in diameter and 100 nm in height. Based on this design, we prepare samples with periods of 7 and 7.9 μm and experimentally demonstrate that a change in the period can cause a change in the emissivity and thus tunability in thermal control performance. The temperature difference between the two samples reaches 44.1 °C at a heating power of 0.28 W/cm2 for both samples. Furthermore, we construct a stretching platform that enables in situ mechanical stretching to realize dynamic changes in emissivity. The integral infrared emissivity of the sample increases from 0.32 to 0.5 at a biaxial tensile strain of 13%, achieving a 56% modulation rate of the integral infrared emissivity. The material is expected to enable dynamic thermal management.

This study introduces the synthesis and detailed characterization of a novel thermochromic material capable of reversible alterations in its thermotropic transmittance. Through an emulsion polymerization process, this newly developed material is composed of 75-85% octadecyl acrylate and 0-7% allyl methacrylate, demonstrating a pronounced discoloration effect across a narrow yet critical temperature range of 24.5-39 °C. The synthesized powder underwent a battery of tests, including differential scanning calorimetry and thermogravimetric analysis, as well as scanning electron microscopy. These comprehensive evaluations confirmed the material\'s exceptional thermal stability, uniform particle size distribution, and strong anchoring properties. Building upon these findings, we advanced the development of thermochromic polyvinyl butyral films and laminated glass products. By utilizing a coextrusion technique, we integrated these films into laminated glass, setting a new benchmark against existing glass technologies. Remarkably, the incorporation of thermochromic PVB films into laminated glass led to a significant reduction in solar irradiance of 20-30%, outperforming traditional double silver low-emissivity glass. This achievement demonstrates the exceptional shading and thermal insulation properties of the material. The research presented herein not only pioneers a valuable methodology for the engineering of smart materials with tunable thermotropic transmittance but also holds the key to unlocking enhanced energy efficiency across a spectrum of applications. The potential impact of this innovation on the realm of sustainable building materials is profound, promising significant strides toward energy conservation and environmental stewardship.

The manipulation of interactions between light and matter plays a crucial role in the evolution of organisms and a better life for humans. As a result of natural selection, precise light-regulatory systems of biology have been engineered that provide many powerful and promising bioinspired strategies. As the \"king of disguise\", cephalopods, which can perfectly control the propagation of light and thus achieve excellent surrounding-matching via their delicate skin structure, have made themselves an exciting source of inspiration for developing optical and thermal regulation nanomaterials. This review presents cutting-edge advancements in cephalopod-inspired optical and thermal regulation nanomaterials, highlighting the key milestones and breakthroughs achieved thus far. We begin with the underlying mechanisms of the adaptive color-changing ability of cephalopods, as well as their special hierarchical skin structure. Then, different types of bioinspired nanomaterials and devices are comprehensively summarized. Furthermore, some advanced and emerging applications of these nanomaterials and devices, including camouflage, thermal management, pixelation, medical health, sensing and wireless communication, are addressed. Finally, some remaining but significant challenges and potential directions for future work are discussed. We anticipate that this comprehensive review will promote the further development of cephalopod-inspired nanomaterials for optical and thermal regulation and trigger ideas for bioinspired design of nanomaterials in multidisciplinary applications.

The development of electronic skin (e-skin) emulating the human skin\'s three essential functions (perception, protection, and thermoregulation) has great potential for human-machine interfaces and intelligent robotics. However, existing studies mainly focus on perception. This study presents a novel, eco-friendly, mechanically robust e-skin replicating human skin\'s three essential functions. The e-skin is composed of Ti3C2Tx MXene, polypyrrole, and bacterial cellulose nanofibers, where the MXene nanoflakes form the matrix, the bacterial cellulose nanofibers act as the filler, and the polypyrrole serves as a conductive \"cross-linker\". This design allows customization of the electrical conductivity, microarchitecture, and mechanical properties, integrating sensing (perception), EMI shielding (protection), and thermal management (thermoregulation). The optimal e-skin can effectively sense various motions (including minuscule artery pulses), achieve an EMI shielding efficiency of 63.32 dB at 78 μm thickness, and regulate temperature up to 129 °C in 30 s at 2.4 V, demonstrating its potential for smart robotics in complex scenarios.

The development of efficient and high-performance electric vehicle (EV) batteries relies on improving various components, such as the anode and cathode electrodes, separators, and electrolytes. This review paper offers an elaborate overview of different materials for these components, emphasizing their respective contributions to the improvement of EV battery performance. Carbon-based materials, metal composites, and polymer nanocomposites are explored for the anode, offering high energy density and capacity. However, they are noted to be susceptible to Li plating. Unique structures, such as Titanium niobium oxide (TiNb2O7), offer high theoretical capacity, quick Li+ intercalation, and an extended lifecycle. Meanwhile, molybdenum disulfide (MoS2), with 2D and 3D structures, exhibits high reversible specific capacity, outstanding rate performance, and cyclic stability, showing promising properties as anode material. For cathodes, lithium-iron phosphate (LFP), lithium-cobalt oxide (LCO), lithium-nickel-cobalt-aluminum oxide (NCA), lithium-nickel-manganese-cobalt oxide (NMC), and cobalt-free lithium-nickel-manganese oxide (NMO) are considered, offering specific energy and capacity advantages. For instance, LFP cathode electrodes show good thermal stability, good electrochemical performance, and long lifespan, while NMC exhibits high specific energy, relatively high capacity, and cost savings. NCA has a high specific energy, decent specific power, large capacity, and a long lifecycle. NMO shows excellent rate capability, cyclic stability, and cost-effectiveness but with limited cycle performance. Separator innovations, including polyolefin materials, nanofiber separators, graphene-based composites, and ceramic-polymer composites, are analyzed for use as separators, considering mechanical strength, porosity, wettability with the electrolyte, electrolytic absorption, cycling efficiency, and ionic conductivity. The electrolyte comprises lithium salts such as lithium tetrafluoroborate (LiBF4), lithium hexafluorophosphate (LiPF6), and other salts dissolved in carbonate solvents. This improves energy density, capacity, and cycling stability and provides high ion mobility and resistance to decomposition. By examining the existing literature, this review also explores research on the solid electrolyte interface (SEI) and lithium plating, providing valuable insights into understanding and mitigating these critical issues. Despite the progress, limitations such as practical implementation challenges, potential cost implications, and the need for further research on scale-up feasibility and long-term durability are acknowledged. These efforts to enhance the electrochemical characteristics of key battery parameters-positive and negative electrodes, separators, and electrolytes-aim to improve capacity, specific energy density, and overall energy density. These continuous endeavours strive for faster charging of EV batteries and longer travel ranges, contributing to the ongoing evolution of EV energy storage systems. Thus, this review paper not only explores remarkable strides in EV battery technology but also underscores the imperative of addressing challenges and propelling future research for sustainable and high-performance electric vehicle energy storage systems.

Phase change materials (PCMs) are crucial for sustainable thermal management in energy-efficient construction and cold chain logistics, as they can store and release renewable thermal energy. However, traditional PCMs suffer from leakage and a loss of formability above their phase change temperatures, limiting their shape stability and versatility. Inspired by the muscle structure, formable PCMs with a hierarchical structure and solvent-responsive supramolecular networks based on polyvinyl alcohol (PVA)/wood composites are developed. The material, in its hydrated state, demonstrates low stiffness and pliability due to the weak hydrogen bonding between aligned wood fibers and PVA molecules. Through treatment of poly(ethylene glycol) (PEG) into the PVA/wood PEG gel (PEG/PVA/W) with strengthened hydrogen bonds, the resulting wood-based PCMs in the hard and melting states elevate the tensile stress from 10.14 to 80.86 MPa and the stiffness from 420 MPa to 4.8 GPa, making it 530 times stiffer than the PEG/PVA counterpart. Capable of morphing in response to solvent changes, these formable PCMs enable intricate designs for thermal management. Furthermore, supported by a comprehensive life cycle assessment, these shape-adaptable, recyclable, and biodegradable PCMs with lower environmental footprint present a sustainable alternative to conventional plastics and thermal management materials.

To address the escalating power consumption of processors in data centers and the growing emphasis on environmental sustainability, the prospective shift from traditional air-cooling to immersion liquid cooling necessitates multiple functional integrations in polymer-based thermal conductive materials. Here, drawing inspiration from mussels, we showed a copolymer, poly(dimethylsiloxane-co-dopamine methacrylate) (PDMS-DMA), with a variety of reversible molecular interactions and simply combined with liquid metal (EGaIn) can yield a flexible, waterproof, and electrically insulating thermal conductive composite. The obtained PDMS-DMA/EGaIn composites demonstrate a harmonious blend of attributes, including a low modulus (75.8 kPa), high thermal conductivity of 6.9 W m-1 K-1, and rapid room-temperature self-healing capabilities, capable of complete repair within 20 min, even under water. Based on its electrically insulating and water resistance properties, PDMS-DMA/EGaIn emerges as a promising candidate for efficient and stable heat transfer in both air and underwater thermal management. Consequently, this water-resistant polymer-based composite holds significance for application in thermal protective layers for future immersion liquid cooling systems.