Electromagnetic Interference Shielding Mechanism Research Articles

Mussel-like carbon fiber/MnO2 nanosheet heterostructures for mechanically strong carbon fiber/polyamide composites with excellent electromagnetic interference shielding

In order to construct carbon fiber (CF) reinforced polyamide 6 (PA6) composites with both excellent mechanical properties and electromagnetic interference (EMI) shielding properties, in this paper, a multiscale coating of PDA-MnO2 is constructed on the CF surface based on the in-situ growth process of polydopamine (PDA) and δ-phase manganese dioxide (δ-MnO2) nanosheets. Interestingly, the introduction of PDA not only improves the yield and the crystal regularity of MnO2 nanosheets, but also enables the strength of CF to be maintained. The interlayer shear strength and interfacial shear strength of the modified CF/PA6 composites are increased by 19.45% and 37.45%, respectively, compared with those of the desized CF/PA6 composites. Meanwhile, the introduction of MnO2 nanosheets also improves the EMI shielding performance of the composites to commercial standards. The interfacial enhancement and EMI shielding mechanisms of the composites are elaborated, which enriches the theoretical system of CF composites for multifunctional applications.

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.

Fabrication of electrically conductive interconnected microcellular thermoplastic elastomeric foam composite for absorption dominating electromagnetic interference shielding with ultra low reflection

AbstractThe elevated rates of electromagnetic radiation pollution, resulting from the growing need for wireless communication systems and electronic gadgets, have sparked interest in creating shielding materials that are lightweight, flexible, non‐corrosive, simply processable, and affordable. In this study, a collection of microcellular nanocomposites based on ethylene octane copolymer (EOC) were created utilizing Vulcan XC 72 conductive carbon black (VCB) by a dual mixing process involving both melt and solution mixing. A chemical blowing agent was utilized to induce the cellular architecture in the composite, resulting in its lightweight nature (maximum density of 0.65 g/cc). The composite foam, when loaded with 30 parts per hundred of volume (phr) of VCB, displays a conductive network and also achieves an electromagnetic interference (EMI) shielding efficiency of 23.2 decibels (dB), satisfying commercial requirements. Furthermore, the findings indicated that the composite's cellular structure significantly influences the absorption‐dominated EMI shielding mechanism with an absorption rate of 89%–94% and a specific shielding effectiveness of 194 dBcm2/g within the frequency range of 8.2–12.4 GHz (X band). The foam composite also demonstrated as a thermal management system, with a maximum thermal conductivity of 0.3 W/mK. As a result, this lightweight, easily processable, electrical conductive EOC/VCB polymer composite foams are projected to be used as EMI shielding materials in electronics, cars, and packaging.Highlights Fabrication of lightweight microcellular Carbon black‐loaded EOC composite Rheological, mechanical, and thermal properties of foam composites The cell density filled composites reduces by the cellular foam structures Carbon black pronouncedly enhanced the electrical conductivity of foam composite An absorption‐dominated shielding effectiveness with ultra‐low reflection.

Highly tunable rGO composites for EMI shielding inks: A tailored approach to modulate broadband EMI shielding

In this study, we demonstrate the ability to design tunable electromagnetic interference (EMI) shielding by controlling the dominant shielding mechanism, whether it is absorption or reflection, using graphene-based nanocomposites. We synthesized four different composites and their corresponding acrylic- based inks to investigate the impact of additives on the EMI shielding mechanism. We conducted measurements on both liquid and printable structures, and the results were highly promising. The coatings exhibited a maximum shielding efficiency of over 200 dB/mm. To achieve targeted shielding for specific frequency bands (here 10 GHz), we tested metastructures printed with the synthesized inks for their shielding effectiveness. Remarkably, these structures, when screen printed on flexible and transparent polyvinyl chloride substrate, achieved over 90% microwave attenuation. Overall, this research highlights the potential of printable EMI shielding solutions, enabled by graphene-based nanocomposites, to effectively address microwave interference issues in a wide range of electronic devices and defence applications.

Review on recent progress in epoxy‐based composite materials for Electromagnetic Interference(EMI) shielding applications

AbstractThe densely packed electronic components in electronic devices emit electromagnetic (EM) radiations, and the interaction of the emitted EM radiations with external EM signals of neighboring components leads to device malfunctions and also creates health issues in human beings. Particularly, in aircraft, EM interference is a serious threat that leads to disastrous outcomes. The shielding of electronic components is an ideal way to reduce the pollution of electromagnetic interference (EMI). The mechanism of EMI shielding efficiency is discussed elaborately in this article. The factors associated with the EMI shielding of materials are discussed in detail. The EMI shielding by reflection and absorption are two possible routes to improve the shielding performance of the shielding materials. This article also highlights the EMI shielding mechanisms by reflection and absorption. However, the risk of secondary EM pollution is associated with the reflection of EM waves. This review also outlines the methods to improve the absorption‐based shielding performance of the materials. The significance of the microstructure of the shielding materials in enhancing the absorption‐dominant shielding efficiency is also presented with a detailed analysis. This helps to fabricate the absorption‐dominant EMI shielding materials with suitable microstructures. The EM loss is associated with the magnetic, dielectric, and conduction losses according to EM theory.Highlights This article highlights the recent progress in epoxy‐based EMI shielding materials. EMI shielding mechanisms by reflection and absorption are discussed elaborately. Reviewed the methods to improve the absorption‐based shielding performance in detail. Materials with EMI shielding efficiency greater than 30 dB are highly preferable.

Ultrathin MXene film interaction with electromagnetic radiation in the microwave range

The quick progress in communication technologies demands superior electromagnetic interference (EMI) shielding materials. However, achieving a high shielding effectiveness (SE) with thin films, which is needed for microscale, flexible, and wearable devices, through absorption of EM radiation remains a challenge. 2D titanium carbide MXene, Ti3C2Tx, has been shown to efficiently reflect electromagnetic waves. In this paper, we investigated the electromagnetic shielding of ultrathin printed Ti3C2Tx films and recorded absorption up to 50% for 4 nm-thick films. This behavior is explained by impedance matching. Analysis of the sheet impedance in the X-band frequency range allows us to correlate the EMI shielding mechanism with the electrical conductivity measured within the same range. The average bulk in-plane conductivity for 4 to 40 nm-thick films reaches 106 S/m, while the average relaxation time is estimated at around 2.3 ps. Our figures of merit are similar to those reported for ultrathin metal films, such as gold, showing that an abundant MXene material can replace noble metals. We demonstrate that the MXene conductivity mechanism does not change from direct current to THz. The conventional method of reporting EMI SE is correlated with absolute values of transmitted, reflected, and absorbed power, which allows us to interpret previous results on MXene EMI shielding. Considering the easy deposition of thin MXenes films from solution onto a variety of surfaces, our findings offer an attractive alternative for shielding microscale devices and personal electronics.

3D printing of carbon fiber powder/polylactic acid with enhanced electromagnetic interference shielding

The construction of segregated structures within conductive polymer composites (CPCs) is a promising strategy for enhancing the effectiveness of electromagnetic interference (EMI) shielding. Herein, three-dimensional (3D) printed carbon fiber powder (CF)/polylactic acid (PLA) composites were prepared with various filling ratio, filling pattern, thickness and CF contents. The results showed that CF was uniformly dispersed in the PLA. Additionally, the modulus of the printed CF/PLA composite displayed an improvement in comparation to injected composite, despite a decrease of the strength. Within the final printed CF/PLA composite, CF integrated into 3D printed PLA formed an interconnected conductive network based on 3D printing technology. The performances of 3D printed CF/PLA composite exhibited superior comprehensive performance when the filling ratio was 50 %, combined with a grid filling pattern, a thickness of 5 mm, and CF content of 20 %, and its shielding efficiency could reach 99.67 %. Meanwhile, the EMI shielding mechanism of 3D printed CF/PLA composite was dominantly of absorption loss. This work suggests that 3D printing technology provides a simple and effective method for developing 3D printed CF/PLA composite with excellent EMI performance, suitable for different electronic devices and radiation source fields.

Achieving acceptable electromagnetic interference shielding in UHMWPE/ground tire rubber composites by building a segregated network of hybrid conductive carbon black

Polymeric composites with the hybrid filler network for high-performance electromagnetic interference (EMI) shielding brought increasing interest. Herein, UHMWPE/ground tire rubber (GTR)/conductive carbon black (CCB) (UGC) composites with a hybrid segregated structural CCB-GTR were constructed by solid-phase shear milling (S3M), mechanical blending, and compacted molding processes. The percolation behavior of electrical conductivity and EMI shielding effectiveness (SE) of composites was described using Sigmoidal/Growth models, and its EMI shielding mechanism was discussed. Results showed that the EMI SE of U30G70C20, U50G50C20, and U70G30C20 composites were found to be 37.5, 41.7, and 43.8 dB, respectively, due to constructing a hybrid network. The attenuation rate of microwave radiation is above 99.99%, and the shielding mechanism is mainly electrical loss. Moreover, the relationship between electrical conductivity and EMI SE is consistent with Sigmoidal/Growth models, indicating that Sigmoidal/Growth models can successfully predict the percolation threshold of the EMI SE of UGC composites.

Three-Dimensional-Printed Carbon Nanotube/Polylactic Acid Composite for Efficient Electromagnetic Interference Shielding.

High-performance electromagnetic interference (EMI) shielding materials with ultralow density and environment-friendly properties are greatly demanded to address electromagnetic radiation pollution. Herein, carbon nanotube/polylactic acid (CNT/PLA) materials with different CNT contents, which exhibit characteristics of light weight, environmental protection and good chemical stability, are fabricated using 3D printing technology, where CNTs are evenly distributed and bind well with PLA. The performances of 3D-printed CNT/PLA composites are improved compared to pure 3D-printed PLA composites, which include mechanical properties, conductive behaviors and electromagnetic interference (EMI) shielding. The EMI shielding effectiveness (SE) of CNT/PLA composites could be improved when the content of CNTs increase. When it reaches 15 wt%, the EMI SE of 3D-printed CNT/PLA composites could get up to 47.1 dB, which shields 99.998% of electromagnetic energy. Meanwhile, the EMI shielding mechanism of 3D-printed CNT/PLA composites is mainly of absorption loss, and it generally accounts for more than 80% of the total shielding loss. These excellent comprehensive performances endow a 3D-printed CNT/PLA composite with great potential for use in industrial and aerospace areas.

Structure Design and Processing Strategies of MXene-Based Materials for Electromagnetic Interference Shielding.

The development of new materials for electromagnetic interference (EMI) shielding is an important area of research, as it allows for the creation of more effective and high-efficient shielding solutions. In this sense, MXenes, a class of 2D transition metal carbides and nitrides have exhibited promising performances as EMI shielding materials. Electric conductivity, low density, and flexibility are some of the properties given by MXene materials, which make them very attractive in the field. Different processing techniques have been employed to produce MXene-based materials with EMI shielding properties. This review summarizes processes and the role of key parameters like the content of fillers and thickness in the desired EMI shielding performance. It also discusses the determination of power coefficients in defining the EMI shielding mechanism and the concept of green shielding materials, as well as their influence on the real application of a produced material. The review concludes with a summary of current challenges and prospects in the production of MXene materials as EMI shields.

Recent advancements in carbonaceous nanomaterials for multifunctional broadband electromagnetic interference shielding and wearable devices

The ever-increasing proliferation of 5G wireless communication technologies and modern electronics gadgets raises concerns about electromagnetic pollution. Among the myriad e-pollution, electromagnetic interference (EMI) is a recently emphasized realm with much more implications. It affects the performance including malfunctioning and has negative impact on organisms and ecosystems. Therefore, multi-functional EMI shielding materials are essential for minimizing electromagnetic pollution and protecting human beings as well as the nearby devices or systems. In this regard, carbonaceous materials are considered as promising for efficient EMI shielding and microwave absorber due to their synergistic loss mechanism as well as the tunable architecture design. Recent progress revealed that there is significant attention in the construction of carbonaceous material with a unique multiple-interface (i.e. multi-layer, core-shell) framework. More impressively, the multilayer strategic approach is able to relocate the EMI shielding mechanism from reflection to absorption. It generates a significant number of heterogeneous interfaces among the various EM constituents resulting increased interfacial polarisation and dielectric loss. The progress of heterogeneous interface material is endless and this novel class of materials is widely used in various wearable devices and radiation source. Finally, the challenges and prospects on the development of carbon-based multiple-interfaces composites are discussed in detail.

Preparation and optimization of conductive PDMS composite foams with absorption-dominated electromagnetic interference shielding performance via silvered aramid microfibers

Electromagnetic interference (EMI) shielding materials with absorption-dominated EMI shielding mechanism can effectively annihilate electromagnetic waves (EMW) and avoid their repeated EMW pollution. However, it is difficult to achieve this goal for conductive polymer-based composites (CPC), because the interface impedance mismatch between air and CPC leads to massive reflection of EMW at the interface. Pores are beneficial to EMW penetrating into the interior of CPC and causing their multiple reflection, scattering and absorption in pores, thus endowing CPC with absorption-dominated EMI shielding characteristic. Herein, highly conductive silvered aramid microfibers (CAMF) were first synthesized via dopamine-assisted electroless deposition of silver coating on aramid microfibers (AMF), and then the conductive porous PDMS composite foams (PDMSF) with absorption-dominated EMI shielding characteristic were prepared and optimized via salt template method. As a result, PDMSF with 1.7 vol% silver content, the conductivity of PDMSF can reach 10-1 S/m, the EMI shielding efficiency (EMI SE) can reach 36.7 dB in X-band, and the average absorption ratio in EMI SE is 87%, while the density of PDMSF is only 0.28 g/cm3. The combination of lightweight, high EMI SE and absorption-dominated EMI shielding characteristic makes the porous PDMSF the latent EMI shielding materials in special constructions (e.g. military, confidential and nuclear facilities, etc.), aerospace, military equipments and transportation, etc.

Studies on electromagnetic interference shielding effect mechanisms of leaf-like three-dimensional carbon nanotubes/graphene aerogel film and the composites with polydimethylsiloxane

The three-dimensional (3D) structure can improve electromagnetic interference (EMI) shielding effectiveness (SE) of carbon-materials, thereby satisfy the requirement of lightweight. Herein, a leaf-like 3D carbon nanotubes (CNTs)/graphene aerogel film (CGAF) is prepared in which the CNTs are seamlessly embedded in graphene, analogous to veins and mesophyll of a leaf, respectively. The assembly of mesophyll-like graphene into 3D materials not only improves EMI SE, but also changes the EMI shielding mechanism. The addition of veins-like CNTs further amplifies the change of EMI shielding mechanism. The total EMI SE (SEtot) of 3D CGAF is 26.6 dB, which was 3.0 dB and 5.1 dB higher than that of CGP (prepared by compressing CGAF) and GAF (CGAF without CNTs). Besides, the 3D structure makes the absorption SE (SEA) dominates the SEtot of CGAF, accounting for 66.5%, but the reflection SE (SER) is dominant in the SEtot of CGP and the theoretical SEtot of CGAF. This shows that 3D structure can improve the absorption effect by repeatedly reflecting electromagnetic waves (EMWs) from countless pore walls, and the addition of CNTs further synergizes this effect, thus enhancing the SEtot and SEA. Furthermore, the SEMA (SEtot divided by mass per unit area) of CGAF can reach 12091 dB cm2 g−1, which increases by 12.7% and 18.1% compared to CGP and GAF, respectively. In addition, by combining multilayer CGAF with polydimethylsiloxane (PDMS), the SEtot can reach 74.7 dB at 8.2 GHz, and its SEtot still retains 45.6 dB after 100 cycles of bending, still far above the industry standard (20 dB), showing excellent bending resistance.

Directional electromagnetic interference shielding of asymmetric structure based on dual-needle 3D printing

Some special electronic equipment not only need to avoid the interference of external electromagnetic waves (EMWs), but also need to transmit effective signals. Therefore, the development of directional electromagnetic interference (EMI) shielding materials has a great prospect. The asymmetric structure, consisting of the porous magentic rGF (reduced graphene oxide and Fe3O4) layer and the dense electrical conductivity rGM (reduced graphene oxide and MXene) layer, was constructed by dual-needle 3D printing technology. After encapsulation and curing with polydimethylsiloxane (PDMS), the rGF/rGM/PDMS composites were prepared. When the ratio of rGF and rGM layers is 6:4, the SE values of rGF-6/rGM-4/PDMS composites are 38.75 dB and 30.79 dB respectively when EMWs are incident on the rGF layer and rGM layer respectively, and the ΔSE of which is about 8 dB. The results showed that the asymmetric structure composed of porous magnetic layer and dense deeply electric conductive layer could generate a special process of "weak reflection-absorption-strong reflection-reabsorption" for incident EMW. At the same time, the simulation results of the waveguide method validated the experimental results, and further explained the directional EMI shielding mechanism of asymmetric structure. For the first time, this work designs an asymmetric structure based on the double needle 3D printing technology, which provides useful inspiration for the structural design and potential application of directional EMI shielding materials.

Magnetic-conductive bi-gradient structure design of CP/PGFF/Fe3O4 composites for highly absorbed EMI shielding and balanced mechanical strength

• CP/PGFF/Fe 3 O 4 composites were successfully prepared by simple vacuum-assisted filtration and hot-pressing process. • The magnetic-conductive bi-gradient structure was constructed by sieving zero-dimensional Fe 3 O 4 and one-dimensional CNT. • The bi-gradient structured composites reduced reflection coefficient by more than 0.32. • The composites were proven to effectively block the cell phone signals. Developing excellent absorption-dominant electromagnetic interference (EMI) shielding composites is an urgent demand for the rapid development of 5G technology and electronic equipment. Herein, a simple strategy is employed to fabricate carbon nanotubes-polypropylene fibers (CP) /polypropylene-glass fibers felt (PGFF)/Fe 3 O 4 composites with superior EMI shielding effectiveness and low reflection due to the magnetic-conductive bi-gradient structure which is naturally formed by deposition during the vacuum-assisted filtration process. The difference in dimensionality between one-dimensional CNT with outstanding electrical conductivity and zero-dimensional magnetic Fe 3 O 4 nanoparticles is the theoretical basis for the successful construction of the magnetic-conductive bi-gradient structure in a gap-rich PGFF matrix that endows the composites with “absorb-reflect-reabsorb” EMI shielding mechanism. When the electromagnetic waves are incident from the magnetic layer, the EMI shielding effectiveness (SE) reaches 48.9 dB as the weight percentage of the conductive layer increases, more importantly, the reflection coefficients are reduced by more than 0.32 compared with that of another incident pattern. What's more, the resultant composites exhibit an outstanding signal shielding function in the application. This work paves a convenient pathway for designing a magnetic-conductive bi-gradient structure and efficient absorbing EMI shielding composites applied in the next-generated electronic information and communication field.

Structural design and preparation of Ti3C2Tx MXene/polymer composites for absorption-dominated electromagnetic interference shielding.

Electromagnetic interference (EMI) is a pervasive and harmful phenomenon in modern society that affects the functionality and reliability of electronic devices and poses a threat to human health. To address this issue, EMI-shielding materials with high absorption performance have attracted considerable attention. Among various candidates, two-dimensional MXenes are promising materials for EMI shielding due to their high conductivity and tunable surface chemistry. Moreover, by incorporating magnetic and conductive fillers into MXene/polymer composites, the EMI shielding performance can be further improved through structural design and impedance matching. Herein, we provide a comprehensive review of the recent progress in MXene/polymer composites for absorption-dominated EMI shielding applications. We summarize the fabrication methods and EMI shielding mechanisms of different composite structures, such as homogeneous, multilayer, segregated, porous, and hybrid structures. We also analyze the advantages and disadvantages of these structures in terms of EMI shielding effectiveness and the absorption ratio. Furthermore, we discuss the roles of magnetic and conductive fillers in modulating the electrical properties and EMI shielding performance of the composites. We also introduce the methods for evaluating the EMI shielding performance of the materials and emphasize the electromagnetic parameters and challenges. Finally, we provide insights and suggestions for the future development of MXene/polymer composites for EMI shielding applications.

Thermally conductive MWCNTs/Fe3O4/Ti3C2T MXene multi-layer films for broadband electromagnetic interference shielding

• MWCNTs/Fe 3 O 4 /Ti 3 C 2 T x MXene composite film with multi-layer architecture was fabricated by a facile method. • The obtained composite film exhibited high comprehensive performance, including high thermal conduction property and broadband EMI shielding property. • The EMI shielding mechanism of the composite film was comprehensively disclosed. The Ti 3 C 2 T x MXene is thought to be a promising candidate for next-generation electromagnetic interference (EMI) shielding materials. However, its broadband shielding capability and thermal conduction performance are insufficient to meet the growing demands. Herein, we reported a layer-by-layer composite film composed of Ti 3 C 2 T x MXene, multi-walled carbon nanotubes (MWCNTs), and Fe 3 O 4 nanoparticles. Benefitting from the architecture and the synergistic effect of components, the obtained composite film exhibited high comprehensive performance. Specifically, the introduction of Fe 3 O 4 magnetic nanoparticles effectively reduced the impedance mismatch between the composite film and air and enhanced the magnetic loss of the composite film. The layered structure prolonged the transmission path of electromagnetic waves inside the composite film and constructed a rich conductive network, causing interfacial polarization and ohmic loss. The results indicated that the composite film (52 μm) delivered a high EMI shielding effectiveness of 49 dB in the frequency range from X-band to K u -band. Furthermore, the MWCNTs layers in the composite films provided numerous heat transfer channels, reducing phonon scattering during heat transfer and resulting in a maximum thermal conductivity of 8.241 W/(m K).

MOF-derived CoNC@rGO/amine-rich@rGO/fluorinated-epoxy nanocomposites with EMI shielding, mechanical robustness, superamphiphobicity and long-term anticorrosion properties

Along with the rapid development of electronic devices and communication systems, electromagnetic (EM) radiation pollution has become an increasingly serious problem. However, it is greatly challenging to achieve absorption-dominated electromagnetic interference (EMI) shielding and robust multifunctional simultaneously. In this work, we synthesize zeolitic imidazolate framework (ZIF67)-derived CoNC@reduced graphene oxide (rGO) and amine-rich surface rGO (NH2@rGO), and subsequently fabricate NH2-CoNC@rGO-fluorinated epoxy (FEP) nanocomposites by the microwave irradiation strategy, and this is the first time to obtain composite combining excellent EMI shielding, mechanical robustness, superamphiphobicity and long-term anticorrosion properties. Wherein, 3-(perfluoro-n-octyl) propenoxide (PFOP) provides the perfluorinated long chains, which improves both mechanical properties via internal antiplasticization effect, and the dispersity and loading of nanofiller via CF⋯HN/π interactions; 4,4′-hexafluoroisopropylidenediphenol diglycidyl ether (FAEP) increases the compatibility and mechanical robustness; NH2@rGO provides the good interfacial bonding, dielectric attenuation and anode protection; CoNC@rGO endows suitable magnetic and dipolar relaxation loss, micro/nanostructures and cathodic protection. Remarkably, the optimized nanocomposite exhibits satisfied tensile and impact strength (64.4 MPa, 33.7 kJ/m2), EMI shielding properties (56 dB), thermal conductivity (1.13 W·m−1·K−1), superhydrophobicity (154°) and superoleophobicity (151°), self-cleaning, good chemical and mechanical robustness, Joule heating capacity and long-term anticorrosion (30 d). Furthermore, the microwave irradiation effect, multiple EMI shielding and anti-corrosion mechanism have been discussed in detail. This study provides an efficient guideline for designing multicomponent and multidimensional epoxy nanocomposite with EMI shielding and robust multifunctional property in aerospace, underwater equipment, electronic devices and precision construction protection.

Superhydrophobic hollow magnetized Fe3O4 nanospheres/MXene fabrics for electromagnetic interference shielding

The development of high-performance electromagnetic interference (EMI) shielding materials is urgently needed to mitigate electromagnetic radiation pollution. Two-dimensional transition metal carbides (MXenes) are promising EMI shielding materials because of their high metallic electrical conductivity. However, tuning the EMI shielding performance of MXene composites remains challenging via the structure engineering strategy. Herein, we develop a layer-by-layer assembling strategy to construct multilayer sandwiched hollow magnetic Fe3O4 nanospheres (HFO)/MXene on flexible nonwoven fabrics. The fabricated Fe3O4/MXene composite fabrics (HFMs) exhibit low sheet resistance (4.6 Ω/□), super-hydrophobicity, self-cleaning, and good EMI shielding performance (EMI shielding effectiveness of 33.28 dB). More importantly, the EMI shielding mechanism of HFMs is tunable according to the loaded active materials. Thus, the mechanism can alternate from absorption to reflection. Moreover, the HFMs exhibit good electrothermal performance and can be used as a wearable heater for personal thermal management. This work provides a new approach for the structural design of high EMI shielding materials, and paves the way for the development of wearable electronics.

Absorption-based electromagnetic interference shielding composites with sandwich structure by one-step electrodeposition method

The absorption-dominant electromagnetic interference (EMI) shielding materials with light weight, great flexibility, fast heat dissipation and excellent mechanical strength are highly demanded in civil and military applications. In this regard, the absorption-based CNT/Co composite film with sandwich structure (Co/Co-CNT/Co layer) was designed for highly EMI shielding performance and heat dissipation. The existence of Co layers on CNT/Co composite film has suitable impedance matching between film and free space, which can increase EM waves absorption and decrease EM waves reflection. Appropriately incorporating Co nanoparticles into the CNT film can facilitate the interfacial polarization, dipole polarization and dielectric loss derived from conduction loss, thus CNT/Co composite film shows high EMI shielding effectiveness (EMI SE: 49 dB), tensile strength (120 MPa), excellent electrical and thermal conductivity of 61.1 S/cm and 66.8 W/mK respectively. Furthermore, the ratio of absorption (SEA) and total EMI SE (SET) for pristine CNT film is 86.64% and for CNT/Co composite film is 93.31%, and the ratios of A/R for pristine CNT film (0.58) and CNT/Co composite film (1.20) manifest that the EMI shielding mechanism transforms from reflection to absorption. This work offers a novel method to develop the sandwich-structure composites with absorption-dominant EMI shielding performance in the application of advanced multifunctional electromagnetic shielding field.