Electromagnetic Interference SE Research Articles

Composite aerogel with oriented structure of Polyimide@ polypyrrole /MXene for effective shielding against electromagnetic waves and insulation

Although the rapid evolution of electromagnetic wave technology make much progress to society, but has also caused electromagnetic pollution, which poses risks to health, information security, and disrupts communication and device operation. The development of new Electromagnetic Interference (EMI) shielding materials, especially those that are lightweight, easy to process and high shielding efficiency, has become the key to overcoming this challenge. In this study, MXene nanosheets with few layers were fabricated by chemical etching with lithium fluoride (LiF) and hydrochloric acid (HCl). Subsequently, the unidirectional freeze-drying method and vacuum-assisted impregnation method were applied to fabricate Polyimide@ Polypyrrole/MXene (PI@PPy/MXene) composite aerogels with oriented structure. The electromagnetic shielding properties of the oriented PI@PPy composite aerogels were modulated by changing the polymerization time of PPy to control its conductivity. When the polymerization time was set as 7h, the oriented PI@PPy composite aerogel showed the highest EMI efficiency, the value of EMI SE was 19.36dB. With the introduction of MXene, the EMI SE of the PI@PPy/MXene composite gel was increased compared to PI@PPy and reached to 32.64dB. The improvement in electromagnetic shielding performance was attributed to the co-enhancement among the PI aerogel with oriented structure, PPy and MXene, which is the result of the synergisic effect of Multiple reflection losses and polarization losses within the aerogel. The infrared thermography at 200°C showed that with increasing PPy polymerization time, the external temperatures of the samples are 40.3°C, 44.8°C, 51.4°C, 55.4°C and 48.6°C, demonstrating the excellent thermal insulation properties.

Janus structure design of polyimide composite foam for absorption-dominated EMI shielding and thermal insulation

In the present work, by virtue of the synergistic and independent effects of Janus structure, an asymmetric nickel-chain/multiwall carbon nanotube/polyimide (Ni/MWCNTs/PI) composite foam with absorption-dominated electromagnetic interference (EMI) shielding and thermal insulation performances was successfully fabricated through an ordered casting and directional freeze-drying strategy. Water-soluble polyamic acid (PAA) was chosen to match the oriented freeze-drying method to acquire oriented pores, and the thermal imidization process from PAA to PI exactly eliminated the interface of the multilayered structure. By controlling the electro-magnetic gradient and propagation path of the incident microwaves in the MWCNT/PI and Ni/PI layers, the PI composite foam exhibited an efficient EMI SE of 55.8 dB in the X-band with extremely low reflection characteristics (R=0.22). The asymmetric conductive network also greatly preserved the thermal insulation properties of PI. The thermal conductivity (TC) of the Ni/MWCNT/PI composite foam was as low as 0.032 W/(m K). In addition, owing to the elimination of MWCNT/PI and Ni/PI interfaces during the thermal imidization process, the composite foam showed satisfactory compressive strength. The fabricated PI composite foam could provide reliable electromagnetic protection in complex applications and withstand high temperatures, which has great potential in cutting-edge applications such as advanced aircraft.

Flexible Sandwich-Shaped Cellulose Nanocrystals/Silver Nanowires/MXene Films Exhibit Efficient Electromagnetic-Shielding Interference Performance.

The electromagnetic pollution problem is becoming increasingly serious due to the speedy advance of electronic communication devices. There are broad application prospects for the development of flexible, wearable composite films with high electromagnetic interference (EMI)-shielding performance. The MX@AC composite films were prepared from MXene, silver nanowires (AgNWs) and cellulose nanocrystals (CNCs) with a sandwich structure. Benefiting from the upper and lower frame structure formed by winding 1D AgNWs and CNC, the tensile strength of the MX@AC was improved to 35 MPa (12.5 wt% CNC content) from 4 MPa (0 wt% CNC content). The high conductivity of MXene and AgNWs resulted in the MX@AC composite film conductivity up to 90,670 S/m, EMI SE for 90 dB, as well as SSE/t up to 7797 dB cm2 g-1. And the MX@AC composite film was tested for practical application, showing that it can effectively isolate electromagnetic waves in practical application.

Shear-Induced Fabrication of Cellulose Nanofibril/Liquid Metal Nanocomposite Films for Flexible Electromagnetic Interference Shielding and Thermal Management.

To address electromagnetic interference (EMI) pollution in modern society, the development of ultrathin, high-performance, and highly stable EMI shielding materials is highly desired. Liquid metal (LM) based conductive materials have received enormous amounts of attention. However, the processing approach of LM/polymer composites represents great challenges due to the high surface tension and cohesive energy of LMs. In this study, we develop a universal one-step fabrication strategy to directly process composites containing LMs and cellulose nanofibrils (CNFs) and successfully fabricate the ultrathin, flexible, and stable EMI shielding films with an average specific EMI shielding efficiency (EMI SE) value of 429 dB/mm and small thickness of only 70 μm in the wide frequency range of 8.2-18 GHz. In addition, the resulting films also exhibit excellent mechanical performance and flexibility, which endow the film with the ability to withstand repeated folding, bending, and folding into complex shapes without producing cracks or fractures. Besides, the resulting films display excellent thermal conductivity with a λ of 4.90 W/(m K) and an α of 3.17 mm2/s. Thus, the presented approach shows great potential in fabricating advanced materials for EMI shielding applications.

Highly thermally conductive and EMI shielding composite fabricated via free‐radical polymerization of poly acrylic acid assisted by expanded graphite with liquid metal‐grafted MXene

AbstractPolymer composites offer numerous benefits, including low cost, easy processability, and diverse applications. In this work, we fabricated a composite material with high thermal conductivity and electromagnetic interference (EMI) shielding performance using EGaIn, a liquid metal (referred to as LM in this paper), MXene (MX), and expanded graphite (EG) as multifunctional fillers, along with polyacrylic acid (PAA). LM was used to exfoliate MX under the effect of shear force, which not only reduced the size of MX but also increased the aspect ratio of the 2D‐structured MX. MX was filled into the pores of EG to make a heat transfer path, thereby enhancing its thermal conductivity, mechanical properties, and EMI SE properties. LM served as the initiator of free‐radical polymerization to convert acrylic acid (AA) into PAA. Finally, the LMMX/EG/PAA composite was hot‐pressed to make the heat‐transfer path dense. As a result, the LMMX/EG/PAA composite exhibited a thermal conductivity of 1.88 W/m·K and an EMI shielding effect of 52 dB.

The multifunctional flexible conductive viscose fabric prepared by thiol modification followed by copper plating

Based on the current rapid development of electronic products, the development of light-weight, processable, environmentally friendly, long-life, durable, less corrosive, and tunable conductive composite materials with multiple applications may be the development direction of next-generation electronic devices. In this work, for the first time, we employed 3-Mercaptopropyltrimethoxysilane (3-MT) to modify viscose nonwovens and enhance the copper plating process. The prepared samples were characterized by Fourier transform infrared, Wide-angle X-ray diffraction (WAXD), scanning electron microscope + energy dispersive X-ray spectroscopy (SEM + EDS), thermogravimetric analysis (TGA), electrical resistivity, anti-corrosion, Joule heating, and electromagnetic interference (EMI) shielding. Results showed that 3-MT was covalently bound to the viscose surface through hydrolysis and condensation reactions and introduced SH groups. WAXD confirmed that the thiol modification did not change the internal crystal structure of viscose and copper ions. TGA and surface morphology analysis confirmed that the modified viscose promoted the deposition of metal particles in the copper plating process due to the affinity of thiol to metal so that copper particles almost completely wrapped the viscose fibers. In addition, 3MT@Cu@Viscose exhibits extremely low surface and volume resistivity (346.6 and 333.2 mΩ·m), improved corrosion resistance (corrosion rate reduced by 58% compared to the unmodified sample), fast Joule heating response (within 10 s) in low voltage (1 V) and excellent EMI shielding effectiveness (EMI SE > 50 dB). It showed great potential in future multi-functional electronic products such as electric heating sensors, smart clothing, and EMI shielding barrier.

Creation of Wood-Based Hierarchical Superstructures via In Situ Growth of ZIF-8 for Enhancing Mechanical Strength and Electromagnetic Shielding Performance.

Given the escalating prevalence of electromagnetic pollution, there is an urgent need for the development of high-performance electromagnetic interference (EMI) shielding materials. Herein, wood-based electromagnetic shielding materials have gained significant popularity due to their exceptional performance as building materials. In this study, a novel wood-based composite with electromagnetic shielding properties is developed. Through the in situ growth of zeolitic imidazolate framework-8 (ZIF-8) crystals on wood fibers, coupled with uniform integration of carbon nanotubes (CNTs), a multifunctional composite named ZIF-8/Poplar-CNT composite is synthesized via a one-step thermoforming process. The incorporation of CNTs endows the composites with excellent EMI shielding effectiveness (EMI SE). Among these elements, despite ZIF-8 crystals not possessing intrinsic electromagnetic shielding functionality, their distinctive dodecahedral structure proves adept at scattering and reflecting electromagnetic waves within the composites, further improving the electromagnetic shielding effect. Hence, the ZIF-8/Poplar-CNT composite (56.95dB) has ≈10dB higher EMI SE compared to that of the composites without ZIF-8 crystals. Meanwhile, ZIF-8 crystals endow the materials with excellent tensile strength (54.84MPa, enhanced by 4 times). Moreover, the introduction of Zn2+ provides superior antibacterial properties. The potential applications of ZIF-8/Poplar-CNT composites extend to diverse areas such as building decoration, electronic products, and medical equipment.

Facile Construction of Chestnut-Like Structural Fireproof PDMS/Mxene@BN for Advanced Thermal Management and Electromagnetic Shielding Applications.

Composite polymer materials featured superior thermal conductivity, flame retardancy, and electromagnetic shielding performance are increasingly in demand due to the rapid development of highly miniaturized, portable, and flexible electronic devices. Herein, a facile and green ball milling shear method is utilized for generating MXene@Boron nitride (MXene@BN). The multi-functional fillers (MXene@BN) are constructed and incorporated into polydimethylsiloxane (PDMS) to prepare a multifunctional composite (PDMS/MXene@BN) for achieving improved electromagnetic interference (EMI) shielding performance and thermal conductivity as well as flame retardancy simultaneously. When the PDMS/MXene@BN composite has a MXene@BN loading of 2.4 wt.%, it exhibits a high thermal conductivity of 0.59Wm-1K-1, which is 210% higher than that of the pure PDMS matrix. This is attributed to its unique chestnut-like double-layer structure. With a smoke production rate (SPR) of 0.04 m2s-1 and total smoke production (TSP) of 3.51 m2, PDMS/MXene@BN 2.4 composite exhibits superb smoke suppression properties. These SPR and TSP values are 63.20% and 63.50% lower than the corresponding values of pure PDMS. Moreover, the EMI SE of the PDMS/MXene@BN 2.4 can reach 26.3dBat 8.5GHz. The work reported herein provides valuable insight into developing composites with multiple functions, which show strong potential for application in advanced packaging materials.

Ti3C2Tx MXene- and Sulfuric Acid-Treated Double-Network Hydrogel with Ultralow Conductive Filler Content for Stretchable Electromagnetic Interference Shielding.

Hydrogels are emerging as stretchable electromagnetic interference (EMI) shielding materials because of their tissue-like mechanical properties and water-rich porous cellular structures. However, achieving high-performance hydrogel shields remains a challenge because enhancing conductivity often results in a compromise in deformation adoptability. This work proposes a treatment strategy involving sulfuric acid/titanium carbide MXene, which can simultaneously enhance the conductivity and stretchability of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/poly(vinyl alcohol) (PVA) double-network hydrogels. Multiple spectroscopic characterizations reveal that sulfuric acid promotes the linear conformation transition of the PEDOT molecular chain, while MXene increases charge delocalization and hydrogen bond cross-linking sites. The hydrogels, synthesized with a combined content of 0.6 wt % of MXene and PEDOT:PSS, exhibit an average X-band EMI SE of 41 dB. This performance is sustained at 94.5%, even following stretching and release at a strain of 200%. Interestingly, the EMI SE is found to linearly increase, reaching a value of 99 dB as the frequency is increased to 26.5 GHz. This increase is attributed to the enhanced water molecular polarization process, as supported by theoretical calculations of the impedance and attenuation constant. This work introduces a post-treatment technique that optimizes double-network hydrogels, providing deep insights into their EMI shielding mechanism and enabling high-performance EMI shielding with an ultralow conductive filler content.

Improving flame retardant and electromagnetic interference shielding properties of poly(lactic acid)/poly(ε-caprolactone) composites using catalytic imidazolium modified CNTs and ammonium polyphosphate

The flame retardants and electromagnetic interference (EMI) shielding performance were enhanced by using imidazolium-functionalized polyurethane (IPU) modified multi-walled carbon nanotubes (CNTs) and ammonium polyphosphate (APP) for polylactic acid (PLA)/polycaprolactone (PCL) composites. The PLA/PCL/10APP/8CNT/1.6IPU composite containing 10 wt% APP and 8 wt% imidazolium modified CNTs reached the limiting oxygen index (LOI) value of 30.3 % and passed the V-0 rating in UL-94 tests. Moreover, the peak of the heat release rate (pHRR) and total heat release (THR) for this composite reached around 302 kW/m2 and 64 KJ/m2, which were decreased by 39.1 % and 15.8 % compared with that of PLA/PCL/10APP composite. The improved flame retardancy was attributed to the interplay of catalytic, barrier, and condensed char forming of imidazolium-modified CNTs and APP. IPU catalyzed the charring effect of the polymer matrix during combustion and regulated the migration of more CNTs to disperse at the two-phase interface. The dispersion of imidazolium-modified CNTs and co-continuous phase structure of the composites can establish continuous conductive pathways. The PLA/PCL/APP/CNT/IPU composite obtained a higher conductivity compared to the PLA/PCL/APP/CNT composite and whose EMI SE reached 33.9 dB, which is a promising candidate for next-generation sustainable and protective plastics.

Recent Trends in Polymeric Foams and Porous Structures for Electromagnetic Interference Shielding Applications.

Polymer-based (nano)composite foams containing conductive (nano)fillers limit electromagnetic interference (EMI) pollution, and have been shown to act as good shielding materials in electronic devices. However, due to their high (micro)structural complexity, there is still a great deal to learn about the shielding mechanisms in these materials; understanding this is necessary to study the relationship between the properties of the microstructure and the porous structure, especially their EMI shielding efficiency (EMI SE). Targeting and controlling the electrical conductivity through a controlled distribution of conductive nanofillers are two of the main objectives when combining foaming with the addition of nanofillers; to achieve this, both single or combined nanofillers (nanohybrids) are used (as there is a direct relationship between electrical conductivity and EMI SE), as are the main shielding mechanisms working on the foams (which are expected to be absorption-dominated). The present review considers the most significant developments over the last three years concerning polymer-based foams containing conductive nanofillers, especially carbon-based nanofillers, as well as other porous structures created using new technologies such as 3D printing for EMI shielding applications. It starts by detailing the microcellular foaming strategy, which develops polymer foams with enhanced EMI shielding, and it particularly focuses on technologies using supercritical CO2 (sCO2). It also notes the use of polymer foams as templates to prepare carbon foams with high EMI shielding performances for high temperature applications, as well as a recent strategy which combines different functional (nano)fillers to create nanohybrids. This review also explains the control and selective distribution of the nanofillers, which favor an effective conductive network formation, which thus promotes the enhancement of the EMI SE. The recent use of computational approaches to tailor the EMI shielding properties are given, as are new possibilities for creating components with varied porous structures using the abovementioned materials and 3D printing. Finally, future perspectives are discussed.

Liquid metal based conductive textile via reactive wetting for stretchable electromagnetic shielding and electro-thermal conversion applications

Developing stretchable electromagnetic interference (EMI) shielding fabrics has long been fascinating, but remains challenging. Inspired by the fluidity of GaInSn based liquid metal (LM), a series of conductive and stretchable textiles was successfully fabricated here. Notably, the collaboration between Ag nanoparticles and flexible LM coating give rise to metallic electrical conductivity (5637 S/m) and distinguished EMI shielding effectiveness (112.8 dB), together with a remarkable shielding value (96.2 dB) even under stretching. Such a well-established conductive pathway can further yield favorable Joule heating performance that enables low-voltage driving warmth retention. Moreover, the LM coating deliver anti-fouling property and robust fastness on the textile substrate, with no discernible reduction in EMI SE observed even after repetitive strain or cyclic washing. These fascinating features, together with the easy processability, are believed to further drive the structure design of novel conductive textile toward wearable applications.

Stretchable, flexible, and breathable MXene/dopamine/thermoplastic polyurethane nanofiber membrane with outstanding strain sensing and electromagnetic interference shielding performances

Outstanding strain sensing and electromagnetic interference (EMI) shielding performances are two important indicators for high-performance nanofiber membrane in flexible wearable electronic device. Here, simple electrospinning was employed to prepare the nanofiber membrane of thermoplastic polyurethane (TPU) as substrate. Then high-performance nanofiber membrane was developed by synthesizing dopamine on TPU nanofibers to form poly-dopamine (PDA) coatings (named PT) and ultrasonically loading MXene on PT (labeled MPT). Specifically, TPU substrate provides flexibility and breathability, PDA coating improves the adhesion between MXene and TPU, and MXene contributes to strain sensing and EMI shielding performances. Owing to the PDA coatings, MPT nanofiber membrane has outstanding EMI shielding efficiency (EMI SE) of 69.86 dB at 150 μm thickness and an absolute effective shielding value of 8383.33 dBcm2g−1. The combination of PDA with MXene improves the EMI SE of the MPT membrane by ∼ 1.6 times compared to other TPU-based membrane. MPT strain sensor exhibits great sensing performance with a remarkable detection threshold of 0.1%, strain coefficient of up to 2600, broad working range of 200%, and rapid response/recovery time (77/186 ms). Meanwhile, MPT strain sensor also shows remarkable ability to real-time monitor human health/motion, such as joint bending, breathing, speaking and heart rate, which makes significant contributions in the field of smart medicine. This nanofiber membrane can provide a universal strategy for the development of intelligent wearable medical devices.

Porifera-Inspired Lightweight, Thin, Wrinkle-Resistance, and Multifunctional MXene Foam.

Transition metal carbides/nitrides (MXenes) demonstrate a massive potential in constructing lightweight, multifunctional wearable electromagnetic interference (EMI) shields for application in various fields. Nevertheless, it remains challenging to develop a facile, scalable approach to prepare the MXene-based macrostructures characterized by low density, low thickness, high mechanical flexibility, and high EMI SE at the same time. Herein, the ultrathin MXene/reduced graphene oxide (rGO)/Ag foams with a porifera-inspired hierarchically porous microstructure are prepared by combining Zn2+ diffusion induction and hard template methods. The hierarchical porosity, which includes a mesoporous skeleton and a microporous MXene network within the skeleton, not only exerts a regulatory effect on stress distribution during compression, making the foams rubber-like resistant to wrinkling but also provides more channels for multiple reflections of electromagnetic waves. Due to the interaction between Ag nanosheets, MXene/rGO, and porous structure, it is possible to produce an outstanding EMI shielding performance with the specific surface shielding effectiveness reaching 109152.4dBcm2 g-1 . Furthermore, the foams exhibit multifunctionalities, such as transverse Joule heating, longitudinal heat insulation, self-cleaning, fire resistance, and motion detection. These discoveries open up a novel pathway for the development of lightweight MXene-based materials with considerable application potential in wearable electromagnetic anti-interference devices.

Hybrid carbonaceous filler as promising additives for EMI SE of PVDF-based composites: Comparison between monolayered and multilayered structures

Flexible conducting polymeric composites (CPC) for applications as electromagnetic interference (EMI) shielding materials were successfully prepared by melt-mixing approach using poly (vinylidene fluoride) (PVDF) as the matrix, loaded with hybrid carbonaceous fillers, carbon nanotube (CNT) and graphene nanoplatelets (GNP). Composites with as low as 3 wt% of filler with conductivity values in between 10−3 S/m (PVDF/GNP) and 10−1 S/m (PVDF/CNT) were successfully prepared by using hybrid with different proportions. Multi-layered structure composites displayed significantly higher EMI SE values than the bulk composites, mainly those constituted by CNT and the CNT/GNP (1.5:1.5 wt%) hybrid. By stacking PVDF/CNT, PVDF/CNT/GNP and PVDF/GNP with different arrangements, on can achieve EMI SE around 22 dB (in X-band) and 27 dB (in Ku-band) with absorption contribution of 65–70 % in the X-band and 77–81 % in the Ku-band frequency ranges. The effect of the hybrid composites on the morphological, rheological and thermal properties and on the ability of the β-phase formation on PVDF composites was also investigated. By combining appropriate CNT/GNP ratio, a good compromise between flexibility, conductivity, processability and EM attenuation with absorption characteristics was achieved, thus favoring promising application in stealth technology and also in communication devices.

From Waste to Value Added Products: Manufacturing High Electromagnetic Interference Shielding Composite from End-of-Life Vehicle (ELV) Waste.

The use of plastics in automobiles is increasing dramatically due to their advantages of low weight and cost-effectiveness. Various products can be manufactured by recycling end-of-life vehicle (ELV) plastic waste, enhancing sustainability within this sector. This study presents the development of an electromagnetic interference (EMI) shield that can be used for protecting electronic devices in vehicles by recycling waste bumpers of ethylene propylene diene monomer (EPDM) rubber from ELVs. EPDM waste was added to a unique combination of 40/60: PP/CaCO3 master batch and conductive nanofiller of carbon nanotubes using an internal melt mixing process. This nanocomposite was highly conductive, with an electrical conductivity of 5.2×10-1S·cm-1 for 5 vol% CNT in a 30 wt% EPDM/70 wt% PP/CaCO3 master batch and showed a high EMI shielding effectiveness of 30.4 dB. An ultra-low percolation threshold was achieved for the nanocomposite at 0.25 vol% CNT. Waste material in the composite improved the yield strain by about 46% and strain at break by 54% in comparison with the same composition without waste. Low cost and light-weight fabricated composite from ELV waste shows high EMI SE for application in electronic vehicles and opens a new path to convert waste to wealth.

Mechanical, Crystallization, Rheological, and Supercritical CO2 Foaming Properties of Polybutylene Succinate Nanocomposites: Impact of Carbon Nanofiber Content.

As a substitute for conventional polymers for the preparation of biodegradable microcellular polymeric foams, polybutylene succinate (PBS) presents one of the most promising alternatives. However, the low melt strength of PBS makes it difficult to produce high-performance microcellular foams. This study aimed to improve the melt strength of PBS and explore the mechanical, thermal, crystalline, rheological, and supercritical CO2 foaming properties of PBS nanocomposites by using carbon nanofibers (CNFs). This study found that nanocomposites containing 7 wt% CNF exhibited the highest tensile strength, Young's modulus, and bending strength. Moreover, the CNF nanofillers were well dispersed in the PBS matrix without significant agglomeration, even at high filler concentrations. Furthermore, the nanocomposites demonstrated improved melting temperature and crystallinity compared with pure PBS. The rheological analysis showed that the addition of CNFs significantly increased PBS viscosity at low frequencies due to the interaction between the PBS molecular chains and CNFs and the entanglement of CNFs, resulting in a more complete physical network formation when the CNF content reached above 3 wt%. During the supercritical CO2 foaming process, the addition of CNFs resulted in increased cell density, smaller cells, and thicker cell walls, with good laps formed between the fibers on the cell walls of nanocomposite foams. Moreover, the electrical conductivity and electromagnetic interference (EMI) shielding properties of the foamed material were studied, and a nanocomposite foam containing 7 wt% CNF showed good electrical conductivity (4.5 × 10-3 S/m) and specific EMI shielding effectiveness (EMI SE) (34.7 dB/g·cm-1). Additionally, the nanocomposite foam with 7 wt% CNF also exhibited good compression properties (21.7 MPa). Overall, this work has successfully developed a high-performance, multifunctional PBS-based nanocomposite foam, making it suitable for applications in various fields.

Hydrophobic Composite Foams with Asymmetric Gradient Sandwich Structure for Excellent Electromagnetic Interference Shielding and Photothermal Response.

The evolution of contemporary electronics urgently requires the use of versatile electromagnetic interference (EMI) shielding materials in complex environments. Interlayer polydimethylsiloxane (PDMS)/Fe3O4@multiwalled carbon nanotubes (MWCNTs) foams were prepared by a simple physical foaming method with excellent flexibility and electromagnetic wave absorption. The bottom nickel aramid paper (NiP) layer creates a dense conductive network by chemical plating technology, which ensures excellent EMI effectiveness. The upper carbon black (CB)/Fe3O4 layer further improves the absorption performance via conductive loss and magnetic loss. With the effective layout of the impedance matching layer, absorbing layer, and conductive shielding layer, the CB/Fe3O4-PDMS/Fe3O4@MWCNTs-NiP composite material achieves an EMI shielding effectiveness (EMI SE) of 61.7 dB and an absorption coefficient of 0.58 at X-band. In addition, the composite foam provides photothermal conversion and hydrophobicity due to the effective stacking of PDMS and CB/Fe3O4. Thus, the multifunctional composite foam presents a broad range of possible applications, benefiting EMI shielding as well as other specific areas.

Multi-layer carbon fiber paper @reduced graphene oxide/Co/C composite with adjustable electromagnetic interference shielding properties

Paper-based composite materials exhibit a marked tendency towards thinner and lighter profiles in the context of electromagnetic interference (EMI) shielding. Carbon fiber paper (CFP) has excellent electrical conductivity and Lightweight base characteristics. However, its single electrical loss characteristic and uncontrollable EMI shielding performance are limited in application. Therefore, we prepared CFP@ graphene oxide (GO)/ZIF-67 composites by chemical bonding and in-situ polymerization, and then prepared CFP@rGO/Co/C composites with integrated structure and function by heat treatment. Layer-by-layer assembly technology was employed to develop composite materials with tunable EMI shielding performance. The composite material has excellent high conductivity (2475.86 S/m) and excellent EMI shielding performance (average X-band EMI efficiency (SE)38.46 dB, absolute shielding effectiveness (SSE/t) = 14388.56 dB cm2 g−1). Through the layer-by-layer assembly technology, the EMI SE performance of the 7-layer assembled material reached 85.83 dB, and the EMI SSE/t reached 32110.51 dB cm2 g−1. Through simulation verification, the EMI shielding performance of the materials is compared, and ideas for EMI material design are provided. In addition, the material also has excellent Joule heating performance, fast electrothermal response and good temperature controllability. The material exhibits remarkable resilience against harsh environmental conditions, including strong acids, bases, organic reagents, ultrasonic waves, combustive processes, and extremely low temperatures. Despite these severe treatments, its performance remains above 90 % intact. This study proposes a magnetic-dielectric synergistic, performance-adjustable CFP-based shielding material, which has great application potential in the future wearable, defense, and aerospace fields.

All-in-one integrated flexible PE@PET/MXene films for high-performance electromagnetic shields with self-reinforced conductivity and mechanical properties

MXene-based composites are deemed as promising electromagnetic interference (EMI) shielding candidates to address the rapidly increasing electromagnetic interference and radiation concerns. However, developing high-performance flexible polymer-MXene composites with excellent EMI shielding efficiency (EMI SE), good mechanical properties and superior serving stability is a significant challenge. Herein, a type of all-in-one designed lightweight, thin, ultra-flexible PE@PET/MXene films are developed using a novel PE@PET nonwoven fabric (NWF) as the supporter. A mussel-inspired polydopamine modification facilitates the uniform loading of MXene, achieving high electrical conductivity of the resultant PE@PET/MXene films. A simple hot-pressing process is then employed to melt the sheath PE component of PE@PET to serve as a “self-glue” in adhering and wrapping the loaded MXene nanosheets, while maintaining the core PET fibers as the internal “steel” skeleton. As such, the resultant PE@PET/MXene films exhibit multiple self-enhancement metrics involving high mechanical strength, good electrical conductivity, robust serving stability, and superior EMI shielding performance. An optimized PE@PET/MXene film can preserve an excellent EMI SE of 50.44 dB and an ultra-high absolute shielding effectiveness (SSE/t) of 10606 dB cm2 g−1. The versatility of PE@PET/MXene EMI shielding films is further indicated by integrating the flame-retardant additives to endow its flame-retardant function, demonstrating excellent versability and expandability.