Controlled Distributed Ti3 C2 Tx Hollow Microspheres on Thermally Conductive Polyimide Composite Films for Excellent Electromagnetic Interference Shielding

Lightweight Copolymerized Polyimide Foams Containing Trifluoromethyl and Siloxane Moieties for Thermal Insulation and Hydrophobic Applications

Lightweight porous materials with integrated cushioning and shock absorption, excellent thermal insulation, and hydrophobicity demonstrate a broad application prospect in high-end engineering sectors. Herein, the fabrication of lightweight polyimide foams (PIFs) containing trifluoromethyl and siloxane moieties was proposed by adopting copolymerization and microwave-assisted foaming processes. The synthesis and preparation of fluorine- and silicon-containing polyester ammonium salt (PEAS) precursor powders and subsequent PIFs, as well as the relationship and mechanism between structure and properties, were systematically explored. The construction of the anisotropic pore structure was attributed to the "bottom-up" directional foaming behavior of the microwave-assisted foaming process, which endowed PIFs with different traits with respect to the pore growth direction. The resulting copolymerized PIFs displayed low density (18.3-27.7 kg/m3), enhanced mechanical flexibility (compressive strength improvement of 26.2%, compression response rate between 97.5 and 99.1%), excellent thermal stability (T5% > 485.2 °C), and thermal insulation performance. Combining the micro/nano pore structure with the presence of hydrophobic trifluoromethyl and siloxane moieties, PIFs exhibited exceptional hydrophobicity with the water contact angle, reaching as high as 145.9° in the vertical direction (parallel to pore growth direction) and 136.3° in the horizontal direction (perpendicular to pore growth direction). Therefore, lightweight, mechanically flexible, thermally insulating, and hydrophobic PIFs were successfully prepared by the proposed approach, which demonstrate potential applications in the aerospace, transportation, microelectronics, and nuclear energy sectors, among others.

Excellent absorption-dominant electromagnetic interference shielding performances of asymmetric gradient layered composite films exploited with assistance of machine learning

Developing high-performance absorption-dominant electromagnetic interference (EMI) shielding composites is essential yet challenging for advanced high-power electronic devices to minimize the second EMI radiation. Traditional experiment-based approaches for shielding material exploitation usually require extensive fabrication and characterization procedures, leading to a long duration and high expense. Herein, machine learning was applied to assist in developing calcium alginate/sodium montmorillonite/CNT@FeCo/CNT (CA/MMT/CNT@FeCo/CNT, CMF/CMFC-x wt%/CMC-y wt%) EMI shielding composites with the asymmetrical gradient layered architecture, triggering the optimization of absorption-dominant EMI shielding properties and reducing experimental costs. The fabricated CMF/CMFC-48.4 wt%/CMC-43.9 wt% film with a small thickness (341.4 μm) exhibits the superior averaged total EMI shielding effectiveness (EMI SET) of 38.9 dB and optimal absorption coefficient (A) of 0.61, when electromagnetic waves (EMWs) are incident from CMF layer. Based on experimental data, the reflection shielding effectiveness (SER), absorption shielding effectiveness (SEA), reflection coefficient (R), and A are utilized to train and test four different machine learning models. Polynomial Linear model (PL) possesses the best prediction accuracy and reliability with the root mean square error (RMSE) of SER and SEA lower than 0.7022, and RMSE of R and A below 0.0361, suggesting that machine learning can effectively alleviate the experimental burden. Moreover, the composite film also features the acceptable mechanical properties and prominent fire resistance, which is vital for the practical application. This work provides a new idea for reducing experimental costs and accelerating the discovery of advanced absorption-dominant EMI shielding materials.

Highly Thermal Conductive and Electromagnetic Shielding Polymer Nanocomposites from Waste Masks

Over 950 billion (about 3.8 million tons) masks have been consumed in the last four years around the world to protect human beings from COVID-19 and air pollution. However, very few of these used masks are being recycled, with the majority of them being landfilled or incinerated. To address this issue, we propose a repurposing upcycling strategy by converting these polypropylene (PP)-based waste masks to high-performance thermally conductive nanocomposites (PP@G, where G refers to graphene) with exceptional electromagnetic interference shielding property. The PP@G is fabricated by loading tannic acid onto PP fibers via electrostatic self-assembling, followed by mixing with graphene nanoplatelets (GNPs). Because this strategy enables the GNPs to form efficient thermal and electrical conduction pathways along the PP fiber surface, the PP@G shows a high thermal conductivity of 87 W m⁻1 K⁻1 and exhibits an electromagnetic interference shielding effectiveness of 88 dB (1100 dB cm-1), making it potentially applicable for heat dissipation and electromagnetic shielding in advanced electronic devices. Life cycle assessment and techno-economic assessment results show that our repurposing strategy has significant advantages over existing methods in reducing environmental impacts and economic benefits. This strategy offers a facile and promising approach to upcycling/repurposing of fibrous waste plastics.

MXene/Carboxylated Cellulose Nanofiber Inks for Direct Ink Writing Electromagnetic Interference Shielding, Humidity Sensing, and Joule Heating

Two-dimensional transition metal carbide/nitride (MXene)-based conductive inks are promising in the scalable production of printed electronics and wearable devices. Nevertheless, to realize desirable rheological properties of MXene-based inks and the multifunction of the resulting printed devices is still challenging. Herein, MXene inks with tunable rheological properties were developed by inducing carboxylated cellulose nanofibers (C-CNFs) modifier. The versatile rheological properties of MXene inks facilitate the preparation of MXene gratings by direct ink writing (DIW) and multifunctional devices integrated with electromagnetic interference (EMI) shielding, Joule heaters, and humidity sensors. The highest average EMI shielding effectiveness (SE) is 33.0 dB, with specific EMI SE up to 137481.5 dB cm2 g-1. Meanwhile, when functioning as a Joule heater, a low-voltage drive and excellent cyclic and long-term stability can be observed. In addition, the humidity-sensing function integrated with wireless transmission shows a maximum response value of 2768%. The MXene gratings fabricated by DIW are multifunctional and can be applied to the next generation of wearable devices.

Shape memory composite membrane with widely programmable electromagnetic shielding effectiveness

The application of shape memory smart materials in the field of electromagnetic interference (EMI) shielding can compensate for their poor adaptability and promote the development of electromagnetic shielding composite materials towards multi-functionality and intelligence. Herein, an intelligent poly(ethylene-co-vinyl acetate)/polydopamine/MXene (EVA/PDA/MXene) composite membrane with tunable electromagnetic shielding capability over a wide range was prepared using electrospinning and dip-coating techniques. Firstly, electrospinning technology was used to prepare highly cross-linked EVA fiber membranes. Secondly, the surface of these membranes was modified with dopamine. And finally, dip-deposition technology was employed to tightly attach MXene nanosheets to the surface of the modified membranes. The electromagnetic shielding effectiveness of the EVA/PDA/MXene-30-6 composite membrane in the X-band (8.2-12.4 GHz) is up to 74.7 dB, and both the shape fixation rate (Rf) and shape recovery rate (Rr) are above 90%. Most importantly, it achieves a reversible tuning of shielding effectiveness from 26.2 dB to 74.7 dB under a tensile strain of 0-30%. Furthermore, the electromagnetic shielding effectiveness of the composite membrane remains virtually unchanged after undergoing continuous bending and folding, and its surface temperature can reach 93.2 °C when subjected to a voltage of 2.5 V, thereby demonstrating exceptional electro-thermal conversion capability. This multifunctional composite membrane, characterized by its adaptability, provides a direction for the development of electromagnetic shielding composites.

Flexible solid-liquid nanocomposite with high surface resistivity for effective electromagnetic interference shielding and heat dissipation

The miniaturization of electronics and increased power density pose significant challenges, including short circuits, electromagnetic interference (EMI) and heat accumulation. Developing electrically insulative materials that integrate EMI shielding and heat dissipation capabilities offers an effective solution. However, developing such materials is challenging due to the inherent conflict between creating electrically and thermally continuous pathways for EMI shielding and heat dissipation while maintaining electrical insulation. Herein, we sequentially integrated boron nitride nanosheet-bridging-liquid metal (BLM) and MXene-bridging-liquid metal (MLM) solid-liquid bi-continuous networks into poly-p-phenylene benzobisoxazole (PBO) nanofiber matrices. This yielded a sandwich-structured nanocomposite (S-PBLM/MLM) that demonstrates high electrical insulation (volume resistivity of 1.9 × 1013 Ω cm, breakdown voltage of 139 kV mm-1), promising EMI shielding performance (68.2 dB at a thickness of 25 μm), and excellent in-plane thermal conductivity (50.3 W m-1 K-1). Meanwhile the S-PBLM/MLM nanocomposite demonstrates stable EMI shielding performance even after enduring harsh conditions, including mechanical wear, high humidity storage, ultrasonication treatment, extreme temperatures, thermal shock and direct burning. Furthermore, the nanocomposite displays high mechanical strength (tensile strength: 252.6 MPa, toughness: 8.8 MJ m-3). This nanocomposite has significant potential in the fields of modern electronics, aerospace, and defense.

Electromagnetic Interference Shielding Films: Structure Design and Prospects

The popularity of portable and wearable flexible electronic devices, coupled with the rapid advancements in military field, requires electromagnetic interference (EMI) shielding materials with lightweight, thin, and flexible characteristics, which are incomparable for traditional EMI shielding materials. The film materials can fulfill the above requirements, making them among the most promising EMI shielding materials for next-generation electronic devices. Meticulously controlling structure of composite film materials while optimizing the electromagnetic parameters of the constructed components can effectively dissipate and transform electromagnetic wave energy. Herein, the review systematically outlines high-performance EMI shielding composite films through structural design strategies, including homogeneous structure, layered structure, and porous structure. The attenuation mechanism of EMI shielding materials and the evaluation (Schelkunoff theory and calculation theory) of EMI shielding performance are introduced in detail. Moreover, the effect of structure attributes and electromagnetic properties of composite films on the EMI shielding performance is analyzed, while summarizing design criteria and elucidating the relevant EMI shielding mechanism. Finally, the future challenges and potential application prospects of EMI shielding composite films are prospected. This review provides crucial guidance for the construction of advanced EMI shielding films tailored for highly customized and personalized electronic devices in the future.

Thermally Conductive Ti3C2Tx Fibers with Superior Electrical Conductivity

High-performance Ti3C2Tx fibers have garnered significant potential for smart fibers enabled fabrics. Nonetheless, a major challenge hindering their widespread use is the lack of strong interlayer interactions between Ti3C2Tx nanosheets within fibers, which restricts their properties. Herein, a versatile strategy is proposed to construct wet-spun Ti3C2Tx fibers, in which trace amounts of borate form strong interlayer crosslinking between Ti3C2Tx nanosheets to significantly enhance interactions as supported by density functional theory calculations, thereby reducing interlayer spacing, diminishing microscopic voids and promoting orientation of the nanosheets. The resultant Ti3C2Tx fibers exhibit exceptional electrical conductivity of 7781 S cm-1 and mechanical properties, including tensile strength of 188.72 MPa and Young's modulus of 52.42 GPa. Notably, employing equilibrium molecular dynamics simulations, finite element analysis, and cross-wire geometry method, it is revealed that such crosslinking also effectively lowers interfacial thermal resistance and ultimately elevates thermal conductivity of Ti3C2Tx fibers to 13 W m-1 K-1, marking the first systematic study on thermal conductivity of Ti3C2Tx fibers. The simple and efficient interlayer crosslinking enhancement strategy not only enables the construction of thermal conductivity Ti3C2Tx fibers with high electrical conductivity for smart textiles, but also offers a scalable approach for assembling other nanomaterials into multifunctional fibers.

Ultrahigh Conductive MXene Films for Broadband Electromagnetic Interference Shielding

Broadband and ultrathin electromagnetic interference (EMI)-shielding materials are crucial for efficient high-frequency data transmission in emerging technologies. MXenes are renowned for their outstanding electrical conductivity and EMI-shielding capability. While substituting nitrogen (N) for carbon (C) atoms in the conventional MXene structure is theoretically expected to enhance these properties, synthesis challenges have hindered progress. Here, it is demonstrated that TixCyNx - y -1Tz MXene films with optimized N content achieve a record-high electrical conductivity of 35 000 S cm-1 and exceptional broadband EMI shielding across the X (8-12.4 GHz), Ka (26.5-40 GHz), and W (75-110 GHz) bands-outperforming all previously reported materials even at reduced thicknesses. By synthesizing a full series of high-stoichiometric TixAlCyNx - y -1 MAX phases without intermediate phases, the impact of N substitution on the physical and electrical properties of TixCyNx - y -1Tz MXene flakes is systematically explored, achieving complete composition tunability in both dispersion and film forms. These findings position TixCyNx - y -1Tz MXenes as promising candidates for applications spanning from conventional lower-frequency domains to next-generation sub-THz electronics.

Self-adaptive and large-area sprayable thermal management coatings for energy saving

Self-adaptive thermal management over large areas is highly attractive since single-mode radiative cooling materials lead to undesired overcooling. However, it remains a challenge that dual-mode switchable materials require artificial stimuli or additional energy for switching between heating and cooling modes. Here, different from dual-mode switching materials driven by artificial stimuli or additional energy, we propose an autonomously self-adaptive dual-modal coating with assembled micro-heterostructures that can engender the multistage scattering of incident light. The resultant coating demonstrates 92% solar reflectivity and 93% emissivity in hot condition. More significantly, the coating reaches 60% visible light optical modulation, which is attributed to the formation and disruption of the conjugation region in the chromogenic molecules, to prevent overcooling in cold condition. A thermal-switchable fabric is further fabricated via large-area spraying processes, demonstrating 2.5 °C warmer in cold condition and 8.7 °C cooler in hot condition compared to white samples. The coating highlights the importance of the large-scale manufacturing of temperature-adaptive materials, providing insights into the application of dynamic radiative cooling in garment, camping, building and other fields.

Stretchable Water-Repellent PEDOT:PSS-Impregnated Polyurethane Nanofiber Mats for Electromagnetic Interference Shielding

High-performance wearable textiles made from poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) hold great promise for electromagnetic interference (EMI) shielding in military and healthcare systems. However, achieving an optimal balance of resilience, flexibility, and electrical properties is challenging due to weak interfacial interactions between PEDOT:PSS and the host substrates. In this study, a robust and stretchable wearable textile fabricated via vacuum-assisted impregnation of PEDOT:PSS is presented onto an electrospun polyurethane (PU) nanofiber mat. The process creates a convoluted interlock network at the interface layer between PEDOT:PSS and PU nanofiber mat, enhanced by the large contact area, effective chemical interactions, and vacuum-induced pressure. This results in exceptional tensile strength of 51.2 MPa, 207% elongation, and 86% elastic recovery, surpassing the practical requirement threshold of wearable textiles and fibers. The robust PU-PEDOT:PSS nanofiber mat shows a normalized EMI shielding effectiveness value of 365.2 dB mm-1 at an ultrathin thickness of 100 µm. This textile is capable of maintaining its shielding performance after continuous loading and unloading cyclic tests up to 100% strain. Additionally, a one-step, durable, fluorine-free spray coating is introduced to protect the textile from moisture and dust, thereby extending its service life for practical outdoor applications.

Bird's-Nest-Inspired, High-Temperature-Resistant Soft Robots with Enhanced Electromagnetic Interference Shielding

The rapid development of aerospace, artificial intelligence, and flexible wearable electronics has led to an increasing demand for multifunctional electromagnetic interference (EMI) shielding materials, especially for lightweight and high-strength biomimetic intelligent actuators. In this study, we present polyolefin elastomer/aramid nanofiber/carbon nanotube (POE/ANF/CNT) composites with a sandwich architecture fabricated via layer-by-layer technology. Actuation is achieved by exploiting the differential thermal expansion coefficients among the layers, where the POE functions as the active layer, while ANFs and CNTs serve as inert reinforcement layers. The bird's-nest-like CNT layer imparts the actuators with repeatable programming capabilities. These intelligent actuators exhibit rapid responses to light, electrical, and thermal stimuli, featuring a low activation energy, high actuation speed, significant deformation, and exceptional fatigue resistance. Inspired by paper cutting and origami techniques, the actuators achieve repeatable morphological programming and complex actuation behaviors. The POE/ANF/CNT composites also demonstrate effective EMI shielding (35.7 dB at 40 wt % CNTs), high tensile strength (39.1 MPa), superior Joule heating performance (301 °C at 20 V voltage), and excellent thermal stabilities (with a maximum decomposition temperature reaching 473 °C). These multifunctional intelligent materials hold significant potential for applications in flexible wearable electronic devices, EMI shielding, and soft robotics.

Comparative electromagnetic shielding performance of Ti3C2Tx-PVA composites in various structural forms: compact films, hydrogels, and aerogels

The structural design of light-weight MXene-polymer composites has attracted significant interest for enhancing both electromagnetic interference (EMI) shielding performance and mechanical strength, which are critical for practical applications. However, a systematic understanding of how various structural configurations of MXene composites affect EMI shielding is lacking. In this study, light-weight Ti3C2Tx-PVA composites were fabricated in three structural forms, hydrogel, aerogel, and compact film, while varying the Ti3C2Tx areal density (14 to 20 mg cm-2) to elucidate the role of structural design in X-band EMI shielding and mechanical properties. The EMI shielding performance depends on the structural configuration and areal density of the MXene in Ti3C2Tx-PVA composites. The shielding effectiveness increases with increasing Ti3C2Tx content in each configuration. At a fixed Ti3C2Tx areal density of 0.02 g cm-2, the Ti3C2Tx-PVA hydrogel demonstrated the highest shielding effectiveness (SE = 70 dB at 10 GHz), attributed to strong dipole polarization and efficient ionic conduction behavior, followed by the compact film (40 dB) and then the aerogel (21 dB). Notably, the aerogel achieved the highest absorption coefficient (A = 0.89) due to the improved impedance matching and pronounced internal reflections, whereas the hydrogel and compact film exhibited reflection-dominated shielding. Furthermore, the incorporation of PVA polymer molecules into Ti3C2Tx MXenes significantly enhanced their mechanical properties across all configurations: the hydrogel achieved high stretchability (636%), the aerogel displayed superior compressive strength (0.215 MPa), and the compact film reached a tensile strength of 56 MPa, each surpassing the performance of its pristine Ti3C2Tx MXene counterpart. Overall, tailoring the structural configuration into a hydrogel, aerogel, or compact film offers versatile routes for optimizing both EMI attenuation and mechanical performance of MXene-polymer composites.

Stretchable, Patterned Carbon Nanotube Array Enhanced by Ti3C2Tx/Graphene for Electromagnetic Interference Shielding

Stretchability and flexibility are essential characteristics for high-performance electromagnetic interference (EMI) shielding materials in wearable and smart devices. However, achieving these mechanical properties while also maintaining high EMI shielding effectiveness (SE) for shielding materials remains a significant challenge. Here, a stretchable patterned carbon nanotube (CNT) array composite film, reinforced with two-dimensional (2D) nanomaterials (Ti3C2Tx and graphene), is fabricated using a straightforward scraping method. The resulting CNT array/Ti3C2Tx/graphene composite films possess a periodic grid structure. Specifically, the composite film with a regular hexagonal pattern demonstrates an EMI SE of 36.5 dB in the X-band at a thickness of 350 μm. Additionally, the composite film exhibits excellent stretchability, flexibility, and stability. After undergoing 10,000 stretching cycles, the EMI SE remains stable. Simulation results further indicate that surface reflection is the primary EMI shielding mechanism. This simple scraping method offers a promising approach for developing stretchable and high-performance EMI shielding films, making them well suited for application in flexible devices.

Interfacial Confinement Derived High-Strength MXene@Graphene Oxide Core-Shell Fibers for Electromagnetic Wave Regulation, Thermochromic Alerts, and Visible Camouflage

Although electrically conductive Ti₃C₂Tx MXene fibers are promising for wearable electronics, the poor inter-sheet interactions and the random stacking structure of MXene sheets seriously hinder electron transport and load transfer of the fibers. Herein, mechanically strong and electrically conductive MXene@graphene oxide (GO) core-shell fibers are fabricated with a coaxial wet-spinning methodology for electromagnetic wave regulation, thermochromic alerts, and visible camouflage. During the coaxial wet-spinning, the trace-carboxylated GO sheets in the shell align readily because of the spatial confinement of the coaxial needle, while the MXene sheets in the core are progressively oriented and flattened because of the spatial confinement of the GO shell. The positively charged chitosan in the coagulating solution enhances the interfacial interactions between the GO and MXene sheets and facilitates the sheet's orientation inside the fibers. Consequently, the highly aligned core-shell fibers exhibit an ultrahigh tensile strength of 613.7 MPa and an outstanding conductivity of ≈7766 S cm-1. Furthermore, fiber-woven textiles not only offer excellent electromagnetic interference shielding performance but also achieve quantitative regulation of electromagnetic wave transmission by adjusting the angle of the double-layered textiles. The textiles can combine with thermochromic coatings for thermotherapy alerts, visual thermochromic warnings, and visible camouflage.

Robust and Reprocessable Biorenewable Polyester Nanocomposites In Situ Catalyzed and Reinforced by Dendritic MXene@CNT Heterostructure

Renewable 2,5-furandicarboxylic acid-based polyesters are one of the most promising materials for achieving plastic replacement in the age of energy and environmental crisis. However, their properties still cannot compete with those of petrochemical-based plastics, owing to insufficient molecular and/or microstructure designs. Herein, we utilize the Ti3C2Tx-based MXene nanosheets for decorating carbon nanotube (CNT) and obtaining the structurally stable and highly dispersed dendritic hetero-structured MXene@CNT, that can act as multi-roles, i.e., polycondensation catalyst, crystal nucleator, and interface enhancer of polyester. The bio-based MXene@CNT/polybutylene furandicarboxylate (PBF) (denoted as MCP) nanocomposites are synthesized by the strategy of "in situ catalytic polymerization and hot-pressing". Benefiting from the multi-scale interactions (i.e., covalent bonds, hydrogen bonds, and physical interlocks) in hybrid structure, the MCP presents exceptional mechanical strength (≈101 MPa), stiffness (≈3.1 GPa), toughness (≈130 MJ m-3), and barrier properties (e.g., O2 0.0187 barrer, CO2 0.0264 barrer, and H2O 1.57 × 10-14 g cm cm-2 s Pa) that are higher than most reported bio-based materials and engineering plastics. Moreover, it also displays satisfactory multifunctionality with high reprocessability (90% strength retention after 5 recycling), UV resistance (blocking 85% UVA rays), and solvent-resistant properties. As a state-of-art high-performance and multifunctional material, the novel bio-based MCP nanocomposite offers a more sustainable alternative to petrochemical-based plastics in packaging and engineering material fields. More importantly, our catalysis-interfacial strengthening integration strategy opens a door for designing and constructing high-performance bio-based polyester materials in future.

Gradient cement pastes with efficient energy dissipation and electromagnetic wave absorption

Modern engineering demands materials that combine mechanical robustness with effective electromagnetic wave absorption, driven by advancements in wireless communication, radar technologies, and smart infrastructure. Here, we construct a gradient cement paste by layering cement slurries with varying concentrations of carbon nanotubes. This gradient design enhances toughness and impact resistance by optimizing microstructural features and interfacial interactions, which facilitate efficient load transfer and stress delocalization. Additionally, the gradient structure improves electromagnetic wave absorption performance through optimized impedance matching and multiple electromagnetic loss mechanisms, including multiple reflections, scattering, and reabsorption of electromagnetic waves within the material. These synergistic properties position gradient cement pastes as promising high-performance, multifunctional materials for mitigating electromagnetic pollution and advancing next-generation infrastructure.

Highly Thermally Conductive and Flame-Retardant Waterborne Polyurethane Composites with 3D BNNS Bridging Structures via Magnetic Field Assistance

The microstructure design for thermal conduction pathways in polymeric electrical encapsulation materials is essential to meet the stringent requirements for efficient thermal management and thermal runaway safety in modern electronic devices. Hence, a composite with three-dimensional network (Ho/U-BNNS/WPU) is developed by simultaneously incorporating magnetically modified boron nitride nanosheets (M@BNNS) and non-magnetic organo-grafted BNNS (U-BNNS) into waterborne polyurethane (WPU) to synchronous molding under a horizontal magnetic field. The results indicate that the continuous in-plane pathways formed by M@BNNS aligned along the magnetic field direction, combined with the bridging structure established by U-BNNS, enable Ho/U-BNNS/WPU to exhibit exceptional in-plane (λ//) and through-plane thermal conductivities (λ⊥). In particular, with the addition of 30 wt% M@BNNS and 5 wt% U-BNNS, the λ// and λ⊥ of composites reach 11.47 and 2.88 W m-1 K-1, respectively, which representing a 194.2% improvement in λ⊥ compared to the composites with a single orientation of M@BNNS. Meanwhile, Ho/U-BNNS/WPU exhibits distinguished thermal management capabilities as thermal interface materials for LED and chips. The composites also demonstrate excellent flame retardancy, with a peak heat release and total heat release reduced by 58.9% and 36.9%, respectively, compared to WPU. Thus, this work offers new insights into the thermally conductive structural design and efficient flame-retardant systems of polymer composites, presenting broad application potential in electronic packaging fields.

Multifunctional Janus-Structured Polytetrafluoroethylene-Carbon Nanotube-Fe3O4/MXene Membranes for Enhanced EMI Shielding and Thermal Management

Herein, a novel Janus-structured multifunctional membrane with integrated electromagnetic interference (EMI) shielding and personalized thermal management is fabricated using shear-induced in situ fibrillation and vacuum-assisted filtration. Interestingly, within the polytetrafluoroethylene (PTFE)-carbon nanotube (CNT)-Fe3O4 layer (FCFe), CNT nanofibers interweave with PTFE fibers to form a stable "silk-like" structure that effectively captures Fe3O4 particles. By incorporating a highly conductive MXene layer, the FCFe/MXene (FCFe/M) membrane exhibits excellent electrical/thermal conductivity, mechanical properties, and flame retardancy. Impressively, benefiting from the rational regulation of component proportions and the design of a Janus structure, the FCFe/M membrane with a thickness of only 84.9 µm delivers outstanding EMI shielding effectiveness of 44.56 dB in the X-band, with a normalized specific SE reaching 10,421.3 dB cm2 g-1, which is attributed to the "absorption-reflection-reabsorption" mechanism. Furthermore, the membrane demonstrates low-voltage-driven Joule heating and fast-response photothermal performance. Under the stimulation of a 3 V voltage and an optical power density of 320 mW cm-2, the surface temperatures of the FCFe/M membranes can reach up to 140.4 and 145.7 °C, respectively. In brief, the FCFe/M membrane with anti-electromagnetic radiation and temperature regulation is an attractive candidate for the next generation of wearable electronics, EMI compatibility, visual heating, thermotherapy, and military and aerospace applications.

Atomic Infusion Induced Reconstruction Enhances Multifunctional Thermally Conductive Films for Robust Low-Frequency Electromagnetic Absorption

Deterministic fabrication of highly thermally conductive composite film with satisfying low-frequency electromagnetic (EM) absorption performance exhibits great potential in advancing the application of 5G smart electric devices but persists challenge. Herein, a multifunctional flexible film combined with hetero-structured Fe6W6C-FeWO4@C (FWC-O@C) as the absorber and aramid nanofibers (ANFs) as the matrix was prepared. Driven by an atomic gradient infusion reduction strategy, the carbon atoms of absorbers can be precisely relocated from carbon shell to core oxometallate lattice, triggering in situ carbothermic reduction for customization of unique oxometallate-carbide heterojunctions and surface geometrical structure. Such an atoms reconstruction process effectively regulates interface electronic structure and magnetic configuration, resulting in enhanced polarization loss from abundant heterointerfaces and crystal defects and magnetic loss from hierarchical structure endowed magnetic coupling interaction, which jointly contributes to the efficient low-frequency EM absorption performance. Eventually, optimized FWC-O@C microplate exhibits a broad absorption bandwidth surpassed the entire C band, and the assembled FWC-O@C/ANFs composite film also performs a high thermal conductivity over 2500 % higher than that of the pure ANFs. These findings provide a new insight into the atomic reconstruction affected EM properties and a generalized methodological guidance for preparing multifunctional thermally conductive composite films.

Asymmetric Structural MXene/PBO Aerogels for High-Performance Electromagnetic Interference Shielding with Ultra-Low Reflection

Electromagnetic interference (EMI) shielding materials with low electromagnetic (EM) waves reflection characteristics are ideal materials for blocking EM radiation and pollution. Materials with low reflectivity must be constructed using materials with excellent EM waves absorption properties. However, materials simultaneously possessing both low reflectivity and excellent EMI shielding performance remain scarce, consequently, multilayer structures need to be developed. Poly(p-phenylene-2,6-benzobisoxazole) nanofibers (PNF) are prepared by deprotonation. PNF are combined with MXene and heterostructure MXene@Ni prepared by in-situ growth; MXene@Ni/PNF acts as an EM absorption layer while MXene/PNF acts as an EM reflective layer. Finally, (MXene@Ni/PNF)-(MXene/PNF) aerogels are prepared by layer-by-layer freeze-drying based on the layered modular design concept. Experimental characterizations revealed that (MXene@Ni/PNF)-(MXene/PNF) aerogels enable the efficient absorption-reflection-reabsorption of EM waves, effectively eliminating EMI. When the mass ratio of MXene to Ni in MXene@Ni is 1:6 and the mass fraction of MXene in the reflective layer is 80 wt.%, the (MXene@Ni/PNF)-(MXene/PNF) aerogels exhibit excellent EMI shielding performance (71 dB) and a very low reflection coefficient (R = 0.10). Finite element simulations verified that the developed asymmetric structural aerogels achieve high EMI shielding performance with low reflection characteristics. In addition, (MXene@Ni/PNF)-(MXene/PNF) aerogels display excellent infrared camouflage ability.

Adhesion Strategy for Cross-Linking AgNWs/MXene Janus Membrane: Stretchable and Self-Healing Electromagnetic Shielding and Infrared Stealth Capabilities

Developing lightweight polymer shielding membranes with additional physicochemical properties is of great significance for addressing the complex contemporary security demands. However, precise structural design at the molecular level remains a challenge. Herein, a unique Janus composite membrane is assembled from conductive AgNWs/MXene 1D/2D network and polyurethane elastomer (MPHEA), displaying combined superior electromagnetic shielding effectiveness (EMSE) of up to 80 dB and remarkable infrared stealth capability at a wide temperature range of room temperature to 50 °C. Moreover, the endowed chemical crosslinking in the membrane resulted in the exceptional mechanical strength, self-healing, and superior adhesion. The maintained electromagnetic shielding (over 20 dB) even under a strain of 40% and the recovered shielding efficiency of 90% after mechanical damage and self-healing are observed, which is attributed to the synergistic 3D polymer elastic and 1D/2D conductive network in the multi-dimensional crosslinked MPHEA@AgNWs/MXene composite membrane. This work has represented an excellent micro-nano structure design strategy on multifunctional electromagnetic wave manager in complex application scenario.

Highly Flexible and Ultralight PVA-co-PE-AgNW/MXene Composite Film with Low Filling for Multistage Electromagnetic Interference Shielding

A composite film with multistage mechanisms for effective electromagnetic interference (EMI) shielding in the ultra-wide frequency of 8-20 GHz was designed. Poly(vinyl alcohol-co-ethylene) (PVA-co-PE) nanofibers and twill-structured nylon 6 fabric are used as substrate and filter film, respectively. Subsequently, a PVA-co-PE/silver nanowire (AgNW)/MXene (PVA/Ag/M) composite film is prepared by vacuum filtration, templating, and hot-pressing. A 2.5 wt.% AgNW/MXene content, the EMI shielding efficiency (SE), normalized SE (SE/t), and absolute SE (SSE/t) are 101.6 dB, 7008.3 dB cm-1, and 36501.5 dB cm2 g-1, respectively. These results are attributed to the synergistic EMI shielding mechanisms enabled by the twill gradient structure and highly conductive. The surface twill structure promotes 95% wave adsorption, directing the wave along the film interior, significantly increasing the EM wave collision probability and internal reflection times. The rich number of hydrogen bonds increase the interfacial adhesion between the layers and enhance the tensile stress by up to 26.8 MPa. The PVA/Ag/M exhibits excellent Joule heating, rapid heat dissipation, non-flammability, hydrophobicity, super-flexibility, and stability. This paper presents an effective fabrication strategy for ultralight and highly conformable low-filling films with high strength, excellent EMI SE, and outstanding thermal performance.

A Review on MXene/Nanocellulose Composites: Toward Wearable Multifunctional Electromagnetic Interference Shielding Application

With the rapid development of mobile communication technology and wearable electronic devices, the electromagnetic radiation generated by high-frequency information exchange inevitably threatens human health, so high-performance wearable electromagnetic interference (EMI) shielding materials are urgently needed. The 2D nanomaterial MXene exhibits superior EMI shielding performance owing to its high conductivity, however, its mechanical properties are limited due to the high porosity between MXene nanosheets. In recent years, it has been reported that by introducing natural nanocellulose as an organic framework, the EMI shielding and mechanical properties of MXene/nanocellulose composites can be synergically improved, which are expected to be widely used in wearable multifunctional shielding devices. In this review, the electromagnetic wave (EMW) attenuation mechanism of EMI shielding materials is briefly introduced, and the latest progress of MXene/nanocellulose composites in wearable multifunctional EMI shielding applications is comprehensively reviewed, wherein the advantages and disadvantages of different preparation methods and various types of composites are summarized. Finally, the challenges and perspectives are discussed, regarding the performance improvement, the performance control mechanism, and the large-scale production of MXene/nanocellulose composites. This review can provide guidance on the design of flexible MXene/nanocellulose composites for multifunctional electromagnetic protection applications in the future intelligent wearable field.

Poly(p-Phenylene Benzobisoxazole) Nanofiber: A Promising Nanoscale Building Block Toward Extremely Harsh Conditions

Since the invention and commercialization of poly(p-phenylene benzobisoxazole) (PBO) fibers, numerous breakthroughs in applications have been realized both in the military and aerospace industries, attributed to its superb properties. Particularly, PBO nanofibers (PNFs) not only retain the high performance of PBO fiber but also exhibit impressive nanofeatures and desirable processability, which have been extensively applied in extreme scenarios. However, no review has yet comprehensively summarized the preparation, applications, and prospective challenges of PNFs to the best of our knowledge. Herein, the two fabrication pathways to acquire PNFs from bottom-up to top-down approaches are critically overviewed; the significant advantages and the problem caused simultaneously of the protonation approach compared with other methods are revealed. Besides, the construction strategies of multidimensional PNF-based advanced composites, including 1D fiber, 2D film/nanopaper, and 3D gel, are discussed. Moreover, the outstanding mechanical, insulating, and thermal stability properties of PNFs facilitate their extensive applications in thermal protection, electrical insulation, batteries, and flexible wearable devices, which are further comprehensively introduced. Finally, the perspective and challenges of the fabrication and application of PNFs are highlighted. It demonstrates that the PNFs as one of the promising high-performance nanoscale building blocks can be fully competent using extremely harsh conditions.

Boosting Impedance Matching by Depositing Gradiently Conductive Atomic Layers on Porous Polyimide for Lightweight, Flexible, Broadband, and Strong Microwave Absorption

Gradient structures are effective for microwave absorbing but suffer from inadequate lightweight and poor flexibility, making them fall behind the comprehensive requirements of electromagnetic protection. Herein, we propose a hierarchical gradient structure by integration with porous and sandwich structures. Specifically, polyimide (PI) foams are used as a robust and flexible skeleton, in which the foam cell walls are sandwiched by Ti3C2Tx, ZnO, and ZrO2 atomic layers in sequence. Owing to the decreasing conductivity of Ti3C2Tx, ZnO, and ZrO2, they form gradient impedance matching layers on both sides of the PI foam cell walls, significantly enhancing the absorbing intensity for microwaves. In addition, the porous and sandwich structures can synergistically facilitate multiple reflections, increasing the number of interactions between microwave and foam cell walls. Therefore, the resulting lightweight ZrO2@ZnO@Ti3C2Tx@PI (ZrZnTP) composite foams reach a minimum reflection loss of -68.4 dB with an effective absorbing bandwidth covering the whole X band (8.2-12.4 GHz). The ZrZnTP also exhibits outstanding flexibility even at an extremely low temperature of -196 °C (i.e., liquid nitrogen). This work offers a general approach to realizing hierarchically integrated structures of gradient, porousness, and sandwich structures for lightweight, flexible, broadband, and strong microwave absorbing materials.

Robust Multifunctional Films with Excellent EMI Shielding, Anti-Peeling, and Joule Heating Performances Enabled by an Encapsulated Highly Conductive Fabric Strategy

Recently, the issue of electromagnetic pollution has become increasingly prominent. Flexible polymer films with various conductive fillers are preferred to address this problem due to their highly efficient and durable electromagnetic interference (EMI) shielding performance. However, their applications are restricted by the unbalanced and insufficient electromagnetic wave absorption and shielding capabilities, as well as the weak interlayer bonding force. In this work, robust flexible multifunctional AgNW/MXene/NiCo-C (AMN) films are fabricated by hierarchical casting assembly and an encapsulated conductive fabric strategy. The synergistic effect of the conductive-absorption integrated sandwich core fabric and the conductive encapsulation layer collaborate to provide excellent absorption-dominated EMI shielding (EMI SEmax = 89.12 dB with an ultralow reflectivity value of 0.19) and Joule heating (a high temperature of 103.5 °C at 4.5 V) performances. Besides, AMN films with embedded fabrics as a reinforcement structure achieved enhanced peel (1.97 N mm-1) and tensile (7.85 MPa) strengths through an interface enhancement process (plasma and pre-immersion treatments). In conclusion, this paper proposes a feasible paradigm to prepare flexible multifunctional conductive films, which demonstrate tremendous potential for applications in the wearable electronics and aerospace fields.

A Durable Textile With Advanced Thermal Functions and Electromagnetic Shielding

In the face of increasingly variable cold climates and diverse individual temperature regulation demands, personal thermal management (PTM) textiles with electromagnetic shielding have obtained significant attention. However, the PTM textiles face several challenges, including single heating mode, insufficient durability, and complex preparation processes. Herein, an all-day PTM textile Cotton@PDA/AgNPs (CPANS) with energy-free PRH, energy-saving solar heating, compensatory electrical heating, electromagnetic interference (EMI) shielding, and outstanding durability is fabricated by sequentially growing polydopamine (PDA) and silver nanoparticles (AgNPs) on the cotton fabric (CF). The CPANS exhibits low mid-infrared emissivity (36.6%) and high absorptivity (70.8%), which guarantees the energy-saving heating capability. Moreover, the conductivity of the CPANS is ≈11109 S m-1, enabling an electrical heating temperature of ≈177 °C under a low voltage of 1.1 V and superb EMI shielding effectiveness (≈60 dB). The remarkable adhesive properties of the PDA ensure that the desired durability of the CPANS remains high even after rigorous physical treatments. This innovation shows enormous potential for wearable integrated garments in the future and offers a new ideal for PTM fabrics in the cold.

Controlled Distribution of MXene on the Pore Walls of Polyarylene Ether Nitrile Porous Films for Absorption-Dominated Electromagnetic Interference Shielding Materials

With the increasing application of electronic devices, absorption-dominated electromagnetic interference shielding materials (EMISM) have garnered significant attention for preventing secondary electromagnetic pollution. In this study, polyethyleneimine (PEI)-modified MXene (PEI@MXene) is fabricated and achieved its controlled distribution on the pore walls of polyarylene ether nitrile (PEN) porous films via the phase inversion method (PIM) to obtain a closed porous skeleton of MXene on the pore walls (CPS-MPW). The resulting PEI@MXene/PEN composite film (CFx) exhibited absorption-dominated EMIS efficiency (EMISE). Attributing to the strong interaction between PEI and the hydrophilic segment of amphiphilic Pluronic F127, with its hydrophobic segment anchored by the PEN matrix, PEI@MXene is directionally distributed on the pore walls of CFx. In addition, resulting from the cladding of MXene with PEI and isolating it with closed honeycomb pores, the obtained CFx are insulators without forming a conductive network. As a result, these CFx demonstrate absorption-dominated EMISE with the highest SET of 41.2 dB and coefficient A higher than 0.51. Further continuous hot pressing of CFx results in thinner and denser films with an impressive specific EMISE up to 750 dB cm-1. The successful fabrication of these CPS-MPW-type CFx with absorption-dominated EMISE provides a reference for developing and preparing novel EMISM.

Multi-performance sodium alginate-based composite films for sensing and electromagnetic shielding

As science and technology progress swiftly, the demand for high-performance composite films designed to shield against electromagnetic interference (EMI) and for strain sensing applications has significantly increased, making these films essential components for the future generation of smart wearable electronics. However, designing and developing multifunctional flexible composite films remains a considerable challenge. This study employed vacuum-assisted filtration techniques combined with calcium ion cross-linking to create multifunctional MXene/sodium alginate/liquid metal (MSL) composite films exhibiting exceptional EMI shielding and strain sensing capabilities. The mechanical strength of the MSL composite films was optimized by implementing continuous hydrogen bonding and ionic interactions among MXene, sodium alginate, liquid metal (LM), and calcium ions, resulting in a tensile strength of 71.71 MPa. The composite film exhibits excellent electromagnetic absorption properties, resulting in an exceptional EMI shielding efficacy of 50.61 dB and a specific shielding effectiveness value of 7563 dB·cm2·g-1. This is due to the heterogeneous interface between MXene and LM nanoparticles. Furthermore, the composite film exhibits favorable electrothermal and photothermal conversion capabilities. The film can be a flexible sensor to detect human motion, contingent on the conductive network between MXene and LM. This research illustrates the potential of multifunctional MSL composite films for EMI shielding and human motion monitoring, offering a promising pathway for creating adaptable wearable electronics in challenging electromagnetic conditions.

Highly Thermally Conductive Liquid Crystalline Epoxy Resin Vitrimers with Reconfigurable, Shape-Memory, Photo-Thermal, and Closed-Loop Recycling Performance

The low thermal conductivity, poor toughness, and non-reprocessability of thermosetting epoxy resins severely restrict their applications and sustainable development in flexible electronics. Herein, liquid crystalline epoxy (LCE) and dynamic ester and disulfide bonds are introduced into the cured network of bisphenol A epoxy resin (E-51) to construct highly thermally conductive flexible liquid crystalline epoxy resin (LCER) vitrimers. LCER vitrimers demonstrate adjustable mechanical properties by varying the ratio of LCE to E-51, allowing it to transition from soft to strong. Typically, a 75 mol% LCE to 25 mol% E-51 ratio results in an in-plane thermal conductivity (λ) of 1.27 W m-1 K-1, over double that of pure E-51 vitrimer (0.61 W m-1 K-1). The tensile strength and toughness increase 2.88 folds to 14.1 MPa and 2.45 folds to 20.1 MJ m-3, respectively. Besides, liquid crystalline phase transition and dynamic covalent bonds enable triple shape memory and three-dimensional shape reconstruction. After four reprocessing cycles, λ and tensile strength remain at 94% and 72%, respectively. Integrating carbon nanotubes (CNTs) imparts photo-thermal effect and enables "on" and "off" switch under near-infrared light to LCER vitrimer. Furthermore, the CNTs/LCER vitrimer displays light-induced actuation, self-repairing, and self-welding besides the closed-loop recycling and rapid degradation performance.

High-Precision Printing Sandwich Flexible Transparent Silver Mesh for Tunable Electromagnetic Interference Shielding Visualization Windows

Flexible transparent conductive films (FTCFs) with electromagnetic interference (EMI) shielding performance are increasingly crucial as visualization windows in optoelectronic devices due to their capabilities to block electromagnetic radiation (EMR) generated during operation. Metal mesh-based FTCFs have emerged as a promising representative in which EMI shielding effectiveness (SE) can be enhanced by increasing the line width, reducing the line spacing, or increasing mesh thickness. However, these conventional approaches decrease optical transmittance or increase material consumption, thus compromising the optical performance and economic viability. Hence, a significant challenge still remains in the realm of metal mesh-based FTCFs to enhance EMI SE while maintaining their original optical transmittance and equivalent material usage. Herein, we propose an innovative symmetric structural optimization strategy to create silver mesh-based sandwich-FTCFs with arbitrary customized sizes through high-precision extrusion printing technology for tunable EMI shielding performance. The meticulous adjustment of xy-axis offsets and printing starting point ensures perfect alignment of the silver mesh on both sides of the transparent substrate. This approach yields sandwich-FTCFs with optical transmittance equivalent to single-layer-FTCFs under identical parameters while simultaneously achieving up to 40% enhanced EMI SE. This improvement stems from the synergistic effect of multiple internal reflections and wave interference between the symmetric silver meshes. The excellent shielding performance of sandwich-FTCFs is evidenced through effectively blocking electromagnetic waves from common devices such as mobile phones, Bluetooth earphones, and smartwatches. Our work represents a significant advancement in balancing optical transmittance, EMI SE, and material efficiency in high-performance and cost-effective FTCFs.

Multifunctional electromagnetic wave absorbing carbon fiber/Ti3C2TX MXene fabric with superior near-infrared laser dependent photothermal antibacterial behaviors

Developing multifunctional materials which could simultaneously possess anti-bacterial ability and electromagnetic (EM) absorption ability during medical care is quite essential since the EM waves radiation and antibiotic-resistant bacteria are threatening people's health. In this work, the multifunctional carbon fiber/Ti3C2Tx MXene (CM) were synthesized through repeated dip-coating and following in-situ growth method. The as-fabricated CF/MXene displayed outstanding EM wave absorption and highly efficient photothermal converting ability. The minimum reflection loss (RL) of -57.07 dB and ultra-broad absorption of 7.74 GHz could be achieved for CM composites. By growth of CoNi-layered double hydroxides (LDHs) sheets onto MXene, the absorption bandwidth for carbon fiber/Ti3C2Tx MXene layered double hydroxides (CML) could be reach 5.44 GHz, which could cover the whole Ku band. The excellent photothermal effect endow the CM composites with excellent antibacterial performance. The antibacterials tests indicated that nearly 100 % bactericidal efficiency against E. acoil and S. aureus was obtained for the CM composite after exposure to near-infrared region (NIR) irradiation. This work provides a promising candidate to combat medical device-related infections and EM pollution.

Recent Advances in MXene-Based Aerogels for Electromagnetic Wave Absorption

Developing lightweight, high-performance electromagnetic wave (EMW) absorbing materials those can absorb the adverse electromagnetic radiation or waves are of great significance. Transition metal carbides and/or nitrides (MXenes) are a novel type of 2D nanosheets associated with a large aspect ratio, abundant polar functional groups, adjustable conductivity, and remarkable mechanical properties. This contributes to the high-efficiency assembly of MXene-based aerogels possessing the ultra-low density, large specific surface area, tunable conductivity, and unique 3D porous microstructure, which is beneficial for promoting the EMW absorption. Therefore, MXene-based aerogels for EMW absorption have attracted widespread attention. This review provides an overview of the research progress on MXene-based aerogels for EMW absorption, focusing on the recent advances in component and structure design strategies, and summarizes the main strategies for constructing EMW absorbing MXene-based aerogels. In addition, based on EMW absorption mechanisms and structure regulation strategies, the preparation methods and properties of MXene-based aerogels with varieties of components and pore structures are detailed to advance understanding the relationships of composition-structure-performance. Furthermore, the future development and challenges faced by MXene-based aerogels for EMW absorption are summarized and prospected.

Popcorn-Inspired Expanded Graphite Microspheres with Controlled Morphology and Considerable Conductivity

The structured processing of graphite is complex and challenging, in which expanded graphite plays a crucial role. Given its superior physical and chemical properties, expanded graphite finds extensive application in diverse domains such as electrochemistry and thermal management. However, the traditional preparation process is inconvenient in effectively meeting the design requirements on the macro and micro scales, which presents a challenge for the structured processing of expanded graphite materials. Here, an innovative method is first proposed for the controllable preparation of expanded graphite microspheres. Inspired by the explosion process of popcorn, the controlled gas release inside the natural flake graphite during chemical expansion is regulated by fuming sulfuric acid, realizing the controllable preparation of expanded graphite microspheres. Subsequently, sulfur trioxide can also intensify the degree of oxidation on the surface of the microspheres. The controllable microsphere morphology endows the composite with good isotropic network bonding, with considerable thermal conductivity of 1.703 W m-1 K-1 at low loading of 10 wt.% and reliable cyclic stability. This work opens up a new way for the morphology control of expanded graphite and provides a novel design thought for the physical and chemical structure control of carbon materials in the future.

All-Polymer Composite Film with Outstanding Mechanical, Thermal Conductive, and EMI Shielding Performances

Robust polymer-based composites with high thermal conductivity (TC) and electromagnetic interference shielding effectiveness (EMI SE) hold great promise for applications in rapidly developing electronics. Traditional composites containing inorganic fillers often suffer from increases in processing difficulty, density, and significant deterioration in mechanical properties. Herein, we report for the first time a flexible multilayered all-polymer composite of poly(p-phenyl-2,6-phenylene bisoxazole) (PBO) and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), featuring excellent mechanical strength of 203.9 MPa, in-plane TC of 21.9 W/mK, EMI shielding effectiveness (SE) of 44.2 dB, high-temperature stability, and flame retardancy. The excellent TC, mechanical strength, and flame retardancy of PBO, the remarkable EMI shielding performance of PEDOT:PSS, and the π-π stacking interactions between adjacent layers contribute to the comprehensive properties, which outperform most of the traditional composites of polymers and inorganic fillers reported so far. This full-polymer design may pioneer a new strategy for the preparation of robust and lightweight multifunctional composites.

Multifunctional microwave absorption materials: construction strategies and functional applications

The widespread adoption of wireless communication technology, especially with the introduction of artificial intelligence and the Internet of Things, has greatly improved our quality of life. However, this progress has led to increased electromagnetic (EM) interference and pollution issues. The development of advanced microwave absorbing materials (MAMs) is one of the most feasible solutions to solve these problems, and has therefore received widespread attention. However, MAMs still face many limitations in practical applications and are not yet widely used. This paper presents a comprehensive review of the current status and future prospects of MAMs, and identifies the various challenges from practical application scenarios. Furthermore, strategies and principles for the construction of multifunctional MAMs are discussed in order to address the possible problems that are faced. This article also presents the potential applications of MAMs in other fields including environmental science, energy conversion, and medicine. Finally, an analysis of the potential outcomes and future challenges of multifunctional MAMs are presented.

MXene Hybridized Polymer with Enhanced Electromagnetic Energy Harvest for Sensitized Microwave Actuation and Self-Powered Motion Sensing

Polymeric microwave actuators combining tissue-like softness with programmable microwave-responsive deformation hold great promise for mobile intelligent devices and bionic soft robots. However, their application is challenged by restricted electromagnetic sensitivity and intricate sensing coupling. In this study, a sensitized polymeric microwave actuator is fabricated by hybridizing a liquid crystal polymer with Ti3C2Tx (MXene). Compared to the initial counterpart, the hybrid polymer exhibits unique space-charge polarization and interfacial polarization, resulting in significant improvements of 230% in the dielectric loss factor and 830% in the apparent efficiency of electromagnetic energy harvest. The sensitized microwave actuation demonstrates as the shortened response time of nearly 10 s, which is merely 13% of that for the initial shape memory polymer. Moreover, the ultra-low content of MXene (up to 0.15 wt%) benefits for maintaining the actuation potential of the hybrid polymer. An innovative self-powered sensing prototype that combines driving and piezoelectric polymers is developed, which generates real-time electric potential feedback (open-circuit potential of ~ 3 mV) during actuation. The polarization-dominant energy conversion mechanism observed in the MXene-polymer hybrid structure furnishes a new approach for developing efficient electromagnetic dissipative structures and shows potential for advancing polymeric electromagnetic intelligent devices.

General Approach to Hydrolysis Resistive Aluminum Nitride and Its High-Performance Thermal Interface Materials

Aluminum nitride (AlN), noted for its excellent thermal conductivity and exceptional electrical insulation, presents a promising alternative to traditional ceramic particles in thermal interface materials (TIMs). However, its broader adoption in practical applications is limited by performance degradation due to the vulnerability of its crystal structure to ubiquitous moisture. This study introduces a dual solution, utilizing a mechanochemical method to design a dense outer layer of Galinstan liquid metal (LM) that simultaneously enhances AlN's resistance to hydrolysis and improves its thermal performance in TIM applications. The high surface free energy of the LM layer imparts hydrophobic properties to the AlN surface and, combined with outer metal oxides, forms a dual-layer protective barrier that prevents water penetration, significantly enhancing the TIM's long-term stability in high-humidity conditions. Additionally, the LM layer at the interface improves the thixotropic properties of the TIM and enhances interfacial heat transport through the bridging effect of the LM, resulting in improved rheological mobility and thermal conductivity of the composite material. This win-win surface modification strategy opens opportunities for the practical and durable application of AlN in widespread electronic thermal management.

Leather-Based Shoe Soles for Real-Time Gait Recognition and Automatic Remote Assistance Using Machine Learning

Real-time monitoring of gait characteristics is crucial for applications in health monitoring, patient rehabilitation feedback, and telemedicine. However, the effective and stable acquisition and automatic analysis of gait information remain significant challenges. In this study, we present a flexible sensor based on a carbon nanotube/graphene composite conductive leather (CGL), which uses collagen fiber with a three-dimensional network structure as the flexible substrate. The CGL-based sensor demonstrates a high dynamic range, with notable pressure responses ranging from 0.6 to 14.5 kPa and high sensitivity (S = 0.2465 kPa-1). We further developed a device incorporating the CGL-based sensor to collect foot characteristic signals from human motion and designed smart sports shoes to facilitate effective human-computer interaction. Machine learning was employed to collect and process gait characteristic information in various states, including standing, sitting, walking, and falling. For real-time monitoring of falls, we optimized the K-Nearest Time Series Classifier (KNTC) algorithm, achieving an accuracy of 0.99 and a prediction time of only 13 ms, which highlights the system's excellent intelligent response capabilities. The system maintained a gait recognition accuracy of 90% across diverse populations, with low false-positive (3.3%) and false-negative (3.3%) rates. This work demonstrates stable gait recognition capabilities and provides valuable methods and insights for plantar behavior monitoring and data analysis, contributing to the development of advanced real-time gait monitoring systems.

Excellent Low-Frequency Microwave Absorption and High Thermal Conductivity in Polydimethylsiloxane Composites Endowed by Hydrangea-Like CoNi@BN Heterostructure Fillers

The advancement of thin, lightweight, and high-power electronic devices has increasingly exacerbated issues related to electromagnetic interference and heat accumulation. To address these challenges, a spray-drying-sintering process is employed to assemble chain-like CoNi and flake boron nitride (BN) into hydrangea-like CoNi@BN heterostructure fillers. These fillers are then composited with polydimethylsiloxane (PDMS) to develop CoNi@BN/PDMS composites, which integrate low-frequency microwave absorption and thermal conductivity. When the volume fraction of CoNi@BN is 44 vol% and the mass ratio of CoNi to BN is 3:1, the CoNi@BN/PDMS composites exhibit optimal performance in both low-frequency microwave absorption and thermal conductivity. These composites achieve a minimum reflection loss of -49.9 dB and a low-frequency effective absorption bandwidth of 2.40 GHz (3.92-6.32 GHz) at a thickness of 4.4 mm, fully covering the n79 band (4.4-5.0 GHz) for 5G communications. Meanwhile, the in-plane thermal conductivity (λ∥) of the CoNi@BN/PDMS composites is 7.31 W m-1 K-1, which is ≈11.4 times of the λ∥ (0.64 W m-1 K-1) for pure PDMS, and 32% higher than that of the (CoNi/BN)/PDMS composites (5.52 W m-1 K-1) with the same volume fraction of CoNi and BN obtained through direct mixing.

Kirkendall Effect-Induced Ternary Heterointerfaces Engineering for High Polarization Loss MOF-LDH-MXene Absorbers

Heterogeneous interfacial engineering has garnered widespread attention for optimizing polarization loss and enhancing the performance of electromagnetic wave absorption. A novel Kirkendall effect-assisted electrostatic self-assembly method is employed to construct a metal-organic framework (MOF, MIL-88A) decorated with Ni-Fe layered double hydroxide (LDH), forming a multilayer nano-cage coated with Ti3C2Tx. By modulating the surface adsorption of Ti3C2Tx on LDH, the heterointerfaces in MOF-LDH-MXene ternary composites exhibit excellent interfacial polarization loss. Additionally, the Ni-Fe LDH@Ti3C2Tx nano-cage exhibits a large specific surface area, abundant defects, and a large number of heterojunction structures, resulting in excellent electromagnetic wave absorption performance. The MIL-88A@Ni-Fe LDH@Ti3C2Tx-1.0 nano-cage achieves a reflection loss value of -46.7 dB at a thickness of 1.4 mm and an effective absorption bandwidth of 5.12 GHz at a thickness of 1.8 mm. The heterojunction interface composed of Ni-Fe LDH and Ti3C2Tx helps to enhance polarization loss. Additionally, Ti3C2Tx forms a conductive network on the surface, while the cavity between the MIL-88A core and the Ni-Fe LDH shell facilitates multiple attenuations by increasing the transmission path of internal incident waves. This work may reveal a new structural design of multi-component composites by heterointerfaces engineering for electromagnetic wave absorption.

Porous Structure Fibers Based on Multi-Element Heterogeneous Components for Optimized Electromagnetic Wave Absorption and Self-Anticorrosion Performance

The excellent performance of electromagnetic wave absorbers primarily depends on the coordination among components and the rational design of the structure. In this study, a series of porous fibers with carbon nanotubes uniformly distributed in the shape of pine leaves are prepared through electrospinning technique, one-pot hydrothermal synthesis, and high-temperature catalysis method. The impedance matching of the nanofibers with a porous structure is optimized by incorporating melamine into the spinning solution, as it undergoes gas decomposition during high-temperature calcination. Moreover, the electronic structure can be modulated by controlling the NH4F content in the hydrothermal synthesis process. Ultimately, the Ni/Co/CrN/CNTs-CF specimen (P3C NiCrN12) exhibited superior performance, while achieving a minimum reflection loss (RLmin) of -56.18 dB at a thickness of 2.2 mm and a maximum absorption bandwidth (EABmax) of 5.76 GHz at a thickness of 2.1 mm. This study presents an innovative approach to fabricating lightweight, thin materials with exceptional absorption properties and wide bandwidth by optimizing the three key factors influencing electromagnetic wave absorption performance.

Modulating Electrochemical Energy Storage and Multi-Spectra Defense of MXenes by Interfacial Dual-Filler Engineering

MXenes have attracted growing interest in electrochemical energy storage owing to their high electronic conductivity and editable surface chemistry. Besides, rendering MXenes with spectrum defense properties further broadens their versatile applications. However, the development of MXenes suffers from weak van der Waal interaction-driven self-restacking that leads to random alignment and inferior interface microenvironments. Herein, a nacre-inspired MXene film is tailored by dual-filling of 2-ureido-4[1H]-pyrimidinone (UPy)-modified polyvinyl alcohol (PVA-UPy) and carbon nanotubes (CNTs). The dual-nanofillers engineering endows the nanocomposite film with a highly ordered structure (a Herman's order value of 0.838), a high mechanical strength (139.5 MPa), and continuous conductive pathways of both the ab plane and c-axis. As a proof-of-concept, the tailored nanocomposite film achieves a considerable capacitance of 508.2 F cm-3 and long-term cycling stability without performance degradation for 10 000 cycles. It is efficient for spectra defense in radar and infrared bands, displaying a high electromagnetic shielding capacity (19186 dB cm2 g-1) and a super-low infrared (IR) emissivity (0.16), with negligible performance decay after saving in the air for 1 year, responsible for the applications in specific and complex conditions. This interfacial dual-filler engineering concept showcases effective nanotechnology toward sustainable energy applications with a long lifetime and safety.

Multifunctional Nacre-Like Nanocomposite Papers for Electromagnetic Interference Shielding via Heterocyclic Aramid/MXene Template-Assisted In-Situ Polypyrrole Assembly

Robust, ultra-flexible, and multifunctional MXene-based electromagnetic interference (EMI) shielding nanocomposite films exhibit enormous potential for applications in artificial intelligence, wireless telecommunication, and portable/wearable electronic equipment. In this work, a nacre-inspired multifunctional heterocyclic aramid (HA)/MXene@polypyrrole (PPy) (HMP) nanocomposite paper with large-scale, high strength, super toughness, and excellent tolerance to complex conditions is fabricated through the strategy of HA/MXene hydrogel template-assisted in-situ assembly of PPy. Benefiting from the "brick-and-mortar" layered structure and the strong hydrogen-bonding interactions among MXene, HA, and PPy, the paper exhibits remarkable mechanical performances, including high tensile strength (309.7 MPa), outstanding toughness (57.6 MJ m-3), exceptional foldability, and structural stability against ultrasonication. By using the template effect of HA/MXene to guide the assembly of conductive polymers, the synthesized paper obtains excellent electronic conductivity. More importantly, the highly continuous conductive path enables the nanocomposite paper to achieve a splendid EMI shielding effectiveness (EMI SE) of 54.1 dB at an ultra-thin thickness (25.4 μm) and a high specific EMI SE of 17,204.7 dB cm2 g-1. In addition, the papers also have excellent applications in electromagnetic protection, electro-/photothermal de-icing, thermal therapy, and fire safety. These findings broaden the ideas for developing high-performance and multifunctional MXene-based films with enormous application potential in EMI shielding and thermal management.

Inter-Skeleton Conductive Routes Tuning Multifunctional Conductive Foam for Electromagnetic Interference Shielding, Sensing and Thermal Management

Conductive polymer foam (CPF) with excellent compressibility and variable resistance has promising applications in electromagnetic interference (EMI) shielding and other integrated functions for wearable electronics. However, its insufficient change amplitude of resistance with compressive strain generally leads to a degradation of shielding performance during deformation. Here, an innovative loading strategy of conductive materials on polymer foam is proposed to significantly increase the contact probability and contact area of conductive components under compression. Unique inter-skeleton conductive films are constructed by loading alginate-decorated magnetic liquid metal on the polymethacrylate films hanged between the foam skeleton (denoted as AMLM-PM foam). Traditional point contact between conductive skeletons under compression is upgraded to planar contact between conductive films. Therefore, the resistance change of AMLM-PM reaches four orders of magnitude under compression. Moreover, the inter-skeleton conductive films can improve the mechanical strength of foam, prevent the leakage of liquid metal and increase the scattering area of EM wave. AMLM-PM foam has strain-adaptive EMI shielding performance and shows compression-enhanced shielding effectiveness, solving the problem of traditional CPFs upon compression. The upgrade of resistance response also enables foam to achieve sensitive pressure sensing over a wide pressure range and compression-regulated Joule heating function.

A Flexible Smart Healthcare Platform Conjugated with Artificial Epidermis Assembled by Three-Dimensionally Conductive MOF Network for Gas and Pressure Sensing

The rising flexible and intelligent electronics greatly facilitate the noninvasive and timely tracking of physiological information in telemedicine healthcare. Meticulously building bionic-sensitive moieties is vital for designing efficient electronic skin with advanced cognitive functionalities to pluralistically capture external stimuli. However, realistic mimesis, both in the skin's three-dimensional interlocked hierarchical structures and synchronous encoding multistimuli information capacities, remains a challenging yet vital need for simplifying the design of flexible logic circuits. Herein, we construct an artificial epidermal device by in situ growing Cu3(HHTP)2 particles onto the hollow spherical Ti3C2Tx surface, aiming to concurrently emulate the spinous and granular layers of the skin's epidermis. The bionic Ti3C2Tx@Cu3(HHTP)2 exhibits independent NO2 and pressure response, as well as novel functionalities such as acoustic signature perception and Morse code-encrypted message communication. Ultimately, a wearable alarming system with a mobile application terminal is self-developed by integrating the bimodular senor into flexible printed circuits. This system can assess risk factors related with asthmatic, such as stimulation of external NO2 gas, abnormal expiratory behavior and exertion degrees of fingers, achieving a recognition accuracy of 97.6% as assisted by a machine learning algorithm. Our work provides a feasible routine to develop intelligent multifunctional healthcare equipment for burgeoning transformative telemedicine diagnosis.

MoS2 Lubricate-Toughened MXene/ANF Composites for Multifunctional Electromagnetic Interference Shielding

The design and fabrication of high toughness electromagnetic interference (EMI) shielding composite films with diminished reflection are an imperative task to solve electromagnetic pollution problem. Ternary MXene/ANF (aramid nanofibers)-MoS2 composite films with nacre-like layered structure here are fabricated after the introduction of MoS2 into binary MXene/ANF composite system. The introduction of MoS2 fulfills an impressive "kill three birds with one stone" improvement effect: lubrication toughening mechanical performance, reduction in secondary reflection pollution of electromagnetic wave, and improvement in the performance of photothermal conversion. After the introduction of MoS2 into binary MXene/ANF (mass ratio of 50:50), the strain to failure and tensile strength increase from 22.1 ± 1.7% and 105.7 ± 6.4 MPa and to 25.8 ± 0.7% and 167.3 ± 9.1 MPa, respectively. The toughness elevates from 13.0 ± 4.1 to 26.3 ± 0.8 MJ m-3 (~ 102.3%) simultaneously. And the reflection shielding effectiveness (SER) of MXene/ANF (mass ratio of 50:50) decreases ~ 10.8%. EMI shielding effectiveness (EMI SE) elevates to 41.0 dB (8.2-12.4 GHz); After the introduction of MoS2 into binary MXene/ANF (mass ratio of 60:40), the strain to failure increases from 18.3 ± 1.9% to 28.1 ± 0.7% (~ 53.5%), the SER decreases ~ 22.2%, and the corresponding EMI SE is 43.9 dB. The MoS2 also leads to a more efficient photothermal conversion performance (~ 45 to ~ 55 °C). Additionally, MXene/ANF-MoS2 composite films exhibit excellent electric heating performance, quick temperature elevation (15 s), excellent cycle stability (2, 2.5, and 3 V), and long-term stability (2520 s). Combining with excellent mechanical performance with high MXene content, electric heating performance, and photothermal conversion performance, EMI shielding ternary MXene/ANF-MoS2 composite films could be applied in many industrial areas. This work broadens how to achieve a balance between mechanical properties and versatility of composites in the case of high-function fillers.

3D Printed Leaf-Vein-Like Al2O3/EP Biohybrid Structures with Enhanced Thermal Conductivity

The high computility of electronic components put urgent requirements on the dissipation efficiency of a high thermal conductive substrate. Herein, inspired by the nature structure, leaf-vein-like Al2O3 skeleton was first designed though topology optimization algorithm and manufactured via vat photopolymerization (VPP) 3D printing, then compounded with epoxy (EP) to prepare leaf-vein-like biohybrid structures. The biohybrid structure had a high λ (14.65 Wm-1 K-1 with the solid fraction of 40 vol %), which was 5585% higher than neat EP and 269% higher than the random dispersed Al2O3/EP composite at the same solid amount. Moreover, it further showed a high enhancement in the cooling ecoefficiency of the lighting-emitting diode (LED) cooling system. Compared with 40 vol % random dispersed Al2O3/EP composite as a cooling substrate, the leaf-vein-like biohybrid structure with the same solid fraction reduced the working temperature of LED by 8.9 °C. Our strategy has a significant potential as a viable type and mass-producible bionic cooling substrate.

Centrifugal Inertia-Induced Directional Alignment of AgNW Network for Preparing Transparent Electromagnetic Interference Shielding Films with Joule Heating Ability

Transparent electromagnetic interference (EMI) shielding is highly desired in specific visual scenes, but the challenge remains in balancing their EMI shielding effectiveness (SE) and optical transmittance. Herein, this study proposed a directionally aligned silver nanowire (AgNW) network construction strategy to address the requirement of high EMI SE and satisfactory light transmittance using a rotation spraying technique. The orientation distribution of AgNW is induced by centrifugal inertia force generated by a high-speed rotating roller, which overcomes the issue of high contact resistance in random networks and achieves high conductivity even at low AgNW network density. Thus, the obtained transparent conductive film achieved a high light transmittance of 72.9% combined with a low sheet resistance of 4.5 Ω sq-1 and a desirable EMI SE value of 35.2 dB at X band, 38.9 dB in the K-band, with the highest SE of 43.4 dB at 20.4 GHz. Simultaneously, the excellent conductivity endowed the film with outstanding Joule heating performance and defogging/deicing ability, ensuring the visual transparency of windows when shielding electromagnetic waves. Hence, this research presents a highly effective strategy for constructing an aligned AgNW network, offering a promising solution for enhancing the performance of optical-electronic devices.