Efficient Electromagnetic Interference Shielding Effectiveness Research Articles

Boron-graphene composite for efficient electromagnetic interference shielding with strong strength and near-zero thermal expansion

The quest for the materials that boast efficient electromagnetic interference (EMI) shielding, strong strength and superb thermal dimensional stability is a burgeoning research area, particularly due to their critical applications in safeguarding sensitive circuits against microwave radiation, especially in the space environments. Graphene-based composites, leveraging the remarkable attributes of individual graphene nanosheets, emerge as prime contenders for fulfilling these sophisticated application requirements. In this study, we prepared boron-graphene composites via spark sintering, combining graphene sheets and boron nanoparticles. This method not only ensures high-performance outcomes but also remains cost-effective and suitable for large-scale production. Boron serves as a binder, facilitating the connection between adjacent graphene sheets and enhancing the graphitization process. The resulting composites demonstrated exceptional electrical conductivity (4.53 × 105 S m−1) and superior EMI shielding effectiveness (average SET 83 dB, with the thickness of 0.25 mm), markedly surpassing previous graphene-based materials in terms of compressive strength (171.3 MPa), and exhibiting low thermal expansion and an ultra-low friction coefficient (0.04). Additionally, to unravel the evolution of boron in the graphene composite and the impact of boron on electrical conductivity, first principles calculations and density functional theory (DFT) were utilized. This investigation underscores the significant promise of boron-graphene composites as high-performance, multifunctional materials across various domains.

MXene Functionalized Wood Composite Films for Efficient Electromagnetic Interference Shielding and Pressure Sensing

AbstractDesigning ultra‐light, green, and flexible films for efficient electromagnetic interference (EMI) shielding is crucial yet challenging. Herein, laminated Ti3C2Tx MXene nanosheets are prepared and impregnated into a delignified wood matrix to fabricate composite films. Through a facile drop‐casting and densification strategy, highly aligned cellulose fibers are used for regulating the stacking behavior of MXenes, and the MXenes are encapsulated and attached tightly to the cellulose chains through hydrogen bonds. A high MXene loading up to 32.5 wt.% can be realized, and the resultant MXene/wood film exhibits a tensile strength of 260.7 MPa. The EMI shielding effectiveness is calculated to be 55.5 dB (X‐band, 8.2–12.4 GHz), with a normalized surface‐specific shielding effectiveness of 2673.4 B cm2 g−1. Moreover, the superior electrical conductivity and structural robustness of the composite film give it pressure‐sensing properties and show high sensitivity for monitoring diverse human physiological movements.

Effective electromagnetic interference shields based on cellulose nanofibers-carbon nanotubes layered composites

The rapid development of electronic devices and communication technologies has inadvertently led to the production of significant amounts of Electromagnetic Interference (EMI) and radiation, necessitating the development of sustainable, low-density, affordable, and high-performance EMI shielding materials. The present study involves fabricating a layered composite material comprising alternating substrate and conducting layer made primarily of TEMPO-mediated oxidized cellulose nanofibers (TCNF) and carbon nanotubes (CNT). For the substrate layer, TCNF is modified with optimized polydopamine and Fe3+ concentrations to produce mechanically strong film with a tensile modulus of 12.3 GPa. Furthermore, two CNT/TCNF ratios are used in the conducting film: 60% and 80%. In addition to absorption and reflection, the presence of TCNF in the conducting layer creates an impedance mismatch, resulting in a zigzag reflection mechanism for EMI losses. For a thickness of 212 μm, the 5-layered composite exhibited a notable tensile strength of 58 MPa and an efficient EMI shielding effectiveness (EMI SE) of 39 dB in X-band. The prepared composites meet the requirements for a commercial EMI shielding material, namely >20 dB, and outperform the mechanical strength of many other EMI shielding materials.

Fabrication of silver/polyaniline/aminated graphene oxide coated textiles for electromagnetic interference shielding application within the different bands of frequency

The interference and pollution caused by electromagnetic radiation have become serious concerns due to the advancements in telecommunications and electronic technology. Highly efficient electromagnetic interference (EMI) shielding materials are thus urgently needed. The primary purpose of this research is to design silver/polyaniline/aminated graphene oxide based EMI shielding textiles over a wide frequency range to protect humans from harmful electromagnetic radiation. For this, layer by layer strategy was adapted to develop conductive textiles for remarkable EMI shielding performance in a wide range of frequency. Electroless plating of silver was performed on polyaniline-based aminated graphene oxide (AGO) fabric to achieve a multilayered structure. Our shielding effectiveness (SE) findings demonstrate that these modified fabrics provide excellent EMI shielding efficiency across multiple frequency bands, including UHF, L-band, S-band, C-band, and X-band. The modified fabric showed EMI SE greater than 40 dB in all bands of frequency and it is greater than the commercial requirement. Moreover, these fabrics are antibacterial and hydrophobic in nature and the greatest antibacterial activity was exhibited by silver/polyaniline/aminated graphene oxide fabric about 97 % and 99% against E.coli and S. aureus respectively. These modified fabrics have the potential to significantly reduce electromagnetic radiation pollution and protect human life owing to their exceptional EMI shielding properties.

Simple and Rapid Way to a Multifunctionally Conductive Hydrogel for Wearable Strain Sensors.

Conductive hydrogels have gained increasing attention in the field of wearable smart devices. However, it remains a big challenge to develop a multifunctionally conductive hydrogel in a rapid and facile way. Herein, a conductive tannic acid-iron/poly (acrylic acid) hydrogel was synthesized within 30 s at ambient temperature by the tannic acid-iron (TA@Fe3+)-mediated dynamic catalytic system. The TA@Fe3+ dynamic redox autocatalytic pair could efficiently activate the ammonium persulfate to initiate the free-radical polymerization, allowing the gelation to occur easily and rapidly. The resulting hydrogel exhibited enhanced stretchability (3560%), conductivity (33.58 S/m), and strain sensitivity (gauge factor = 2.11). When damaged, it could be self-healed through the dynamic and reversible coordination bonds between the Fe3+ and COO- groups in the hydrogel network. Interestingly, the resulting hydrogel could act as a strain sensor to monitor various human motions including the huge movement of deformations (knuckle, wrist) and subtle motions (smiling, breathing) in real time due to its enhanced self-adhesion, good conductivity, and improved strain sensitivity. Also, the obtained hydrogel exhibited efficient electromagnetic interference (EMI) shielding performance with an EMI shielding effectiveness value of 24.5 dB in the X-band (8.2-12.4 GHz). Additionally, it displayed antibacterial properties, with the help of the activity of TA.

Tough and durable silver-plated graphene oxide/polyurethane composite foam for efficient electromagnetic shielding

With the rapid development of modern information technology, electromagnetic wave has become a new type of pollution source, so there is an urgent need for an efficient electromagnetic interference (EMI) shielding material to control electromagnetic pollution. Among them, EMI shielding materials in many fields are required to be lightweight, efficient and durable. In this study, silver-plated graphene oxide (GO@Ag) is added as a conductive filler to the polyurethane (PU) matrix, and a composite EMI shielding material with excellent conductive network structure is obtained through co-foaming. Conductive network structure provides high EMI shielding effectiveness (EMI SE) and good mechanical properties for composite shielding materials. When the content of GO@Ag is 15%, the EMI SE reaches 29.4 dB, and the specific EMI SE (SSE) reaches 237.9 dB×cm3 ×g−1. Reflection is the main shielding mechanism of composite shielding materials. Good conductivity makes the shielding materials and air impedance mismatched. When electromagnetic waves contact the shielding materials, the reflection effect will occur. Furthermore, this work provides a new research direction for EMI shielding in the fields of aerospace, precision electronics and lightweight equipment.

Versatile Electronic Textile Enabled by a Mixed-Dimensional Assembly Strategy.

Electronic textiles (e-textiles) hold great promise for serving as next-generation wearable electronics owing to their inherent flexible, air-permeable, and lightweight characteristics. However, these e-textiles are of limited performance mainly because of lacking powerful materials combination. Herein, a versatile e-textile through a simple, high-efficiency mixed-dimensional assembly of 2D MXene nanosheets and 1D silver nanowires (AgNWs) are presented. The effective complementary actions of MXene and AgNWs endow the e-textiles with superior integrated performances including self-powered pressure sensing, ultrafast joule heating, and highly efficient electromagnetic interference (EMI) shielding. The textile-based self-powered smart sensor systems obtained through the screen-printed assembly of MXene-based supercapacitor and pressure sensor are flexible and lightweight, showing ultrahigh specific capacitance (2390 mF cm-2 ), robust areal energy density (119.5 µWh cm-2 ), excellent sensitivity (474.8 kPa-1 ), and low detection limit (1Pa). Furthermore, the interconnected conductive MXene/AgNWs network enables the e-textile with ultrafast temperature response (10.4°C s-1 ) and outstanding EMI shielding effectiveness of ≈66.4dB. Therefore, the proposed mixed-dimensional assembly design creates a multifunctional e-textile that offers a practical paradigm for next-generation smart flexible electronics.

Broadband transparent and flexible silver mesh for efficient electromagnetic interference shielding and high-quality free-space optical communication

A broadband transparent and flexible silver (Ag) mesh is presented experimentally for the first time for both efficient electromagnetic interference (EMI) shielding in the X band and high-quality free-space optical (FSO) communication. High transmission is achieved in a broad wavelength range of 0.4-2.0 µm. The transmittance of the Ag mesh relative to the substrate is around 92% and the sheet resistance is as low as 7.12 Ω/sq. The Ag mesh/polyethylene (PE) achieves a high average EMI shielding effectiveness (SE) of 28.8 dB in the X band with an overall transmittance of 80.9% at 550 nm. High-quality FSO communication with small power penalty is attributed to the high optical transmittance and the low haze at 1550 nm, superior to those of the Ag NW networks. With a polydimethylsiloxane (PDMS) coating, the average EMI SE is still up to 26.2 dB and the overall transmittance is increased to 84.5% at 550 nm due to antireflection. The FSO communication does not change much due to the nearly unchanged optical property at 1550 nm. Both the EMI shielding performance and the FSO communication function maintain after 2-hour chemical corrosions as well as after 1000 bending cycles and twisting. Our PDMS/Ag mesh/PE sandwiched film can be self-cleaned, suitable for outdoor applications.

Rational design of heterointerface between MoO2 and N-doped carbon with tunable electromagnetic interference shielding capacity

Exploring highly efficient electromagnetic interference (EMI) shielding filler is urgently desired for next-generation wireless communication and integrated electronics. In this regard, a series of heterogeneous MoO2/N-doped carbon (MoO2/NC) nanorods with tunable conductivity have been successfully synthesized by regulating the pyrolysis temperature within 600, 700 and 800 °C. Profiting from the rational design of heterointerface and low-dimensional structure, the MoO2/NC powder achieves stronger EMI shielding capacity with the incremental temperature. It is found that the MoO2/NC-800 nanorods exhibit the optimal average EMI shielding effectiveness (SE) of 57.2 dB at a thickness of ∼0.3 mm in the X band. Meanwhile, the corresponding shielding mechanisms of MoO2/NC nanorods are also elaborately explained. More interestingly, the increase of sintering temperature makes an obvious effect on absorption loss but has little influence on reflection loss, demonstrating that adjusting the pyrolysis temperature is an effective strategy to strengthen the electromagnetic energy dissipation.

Lightweight poly(vinylidene fluoride) based quaternary nanocomposite foams with efficient and tailorable electromagnetic interference shielding properties

AbstractDriven by rapidly growing demands in fields such as mobile electronics, aerospace and military, the need for functional materials with lightweight, good environmental stability and efficient electromagnetic interference (EMI) shielding properties has rose sharply. In this paper, quaternary nanocomposite foams comprising of poly(vinylidene fluoride) (PVDF), carbon nanotubes (CNTs), graphene nanoplatelets (GNPs) and Ni were developed by a melt blending and supercritical CO2foaming technology. Compared with pure PVDF, the crystallization temperature of PVDF/2CNTs/2GNPs/12Ni nanocomposite increased remarkably from 139.0 to 144.9°C. Rising the nanofiller loading from 0 to 16 wt% led to the enhancements of around four orders of magnitude in the storage modulus of PVDF nanocomposites as well as about three orders of magnitude in their complex viscosity. For a typical PVDF/2CNTs/2GNPs/12Ni nanocomposite, its EMI shielding effectiveness reached 32.2 dB, brought by dielectric loss and magnetic loss. The electrical conductivity and EMI shielding effectiveness of PVDF nanocomposite foam achieved the optimum values of 0.84 S/m and 19.4 dB, respectively, which originated from the introduction of pore structure and the gradual generation of nanofiller‐nanofiller conductive networks. This study took a promising way toward the fabrication of materials with adjustable EMI shielding property in the fields of electronics and aerospace industries.

Functional composite electromagnetic shielding materials for aerospace, electronics and wearable fields

The rapid development of electronic equipment and communication system has led to the generation of large-scale electromagnetic pollution. Electromagnetic interference (EMI) shielding materials can effectively reduce the harm caused by EMI. However, electromagnetic shielding materials with universal functions cannot effectively exert their electromagnetic interference shielding performance in all fields. EMI shielding materials used in different fields must have specific functionality in their usage conditions. This paper, reviews the functional requirements, fabrication methods, and comprehensive properties of EMI shielding materials in aerospace, electronics, and wearable fields. Composite EMI shielding materials through structural design and raw material selection to obtain excellent functionality and efficient EMI shielding effectiveness. In addition, this paper presents the application prospects of adjustable composite EMI shielding and self-healing EMI shielding materials. We present the main challenges and prospects for future studies of composite EMI shielding materials based on careful consideration.

MXene-decorated carbonized jute composite for high-performance electromagnetic interference shielding

Lightweight, good processability and efficient electromagnetic interference (EMI) shielding materials have captured more interest with the recognition of electromagnetic pollution hazards. Biomass-based carbon has been considered as a promising EMI shielding due to its low cost, renewability and environmental friendliness. Here, we used jute felt as the precursor of biomass carbon to fabricate the MXene (Ti3C2Tx)/jute composite (MXene/CJ) via a simple carbonization process and dip-and-dry method. Higher carbonization temperature and more MXene loading are conducive to electrical conductivity and shielding effectiveness (SE). When the carbonization temperature was 900 °C and dip-and-dry times was 3, the average EMI SE of 59.08 dB was achieved in 8.2–12.4 GHz (X-band) with a reflection-dominated mechanism. Besides, the composite also exhibits the potential to be used as a strain sensor. Under small pressure, the composite possessed excellent sensitivity and response time. The wrist bending, swallowing and vocal cord vibration can be monitored in real-time. These results illustrate that the MXene/CJ composite has a broad prospect in the EMI shielding and wearable electronics fields. This work also provided a feasible approach for the high-value utilization of natural biomass resources.

Utilization of hazardous red mud in silicone rubber/MWCNT nanocomposites for high performance electromagnetic interference shielding

With burgeoning technological advancement in telecommunication and high frequency electronics, its repercussion as electromagnetic pollution is alarmingly high. Hence, much effort has been made to supress this undesired phenomenon using efficient electromagnetic interference (EMI) shielding materials. Red mud, a hazardous by-product of alumina extraction is rich in oxides of iron, aluminium & titanium with ca. 30–60% of hematite, a magnetic lossy material that could be suitable for enhancing microwave absorption and EMI shielding performance of polymer nanocomposites. The impetus for this work was to utilize red mud as magnetically lossy filler in silicone rubber (SR)/multi-wall carbon nanotube (MWCNT) nanocomposites to function as efficient EMI shields with superior microwave absorption. Herein, taking the advantage of conductive percolated network of MWCNT in SR, red mud was incorporated with varying concentration of 5–20 wt% & compression moulded to form flexible sheets. These nanocomposite sheets exhibited a maximum electrical conductivity of 24 S/cm with superior EMI shielding effectiveness value of −83.4 dB in the X band (8.2–12.4 GHz) region making it a suitable candidate for commercial shielding applications. Moreover, sustainable use of a hazardous industrial waste to suppress EMI, which is yet another challenging invisible pollutant, is the key highlight of this work.

Lightweight electromagnetic interference shielding poly(L-lactic acid)/poly(D-lactic acid)/carbon nanotubes composite foams prepared by supercritical CO2 foaming

Lightweight and biodegradable polymer composites with efficient electromagnetic interference (EMI) shielding performance are of great significance for controlling pollution caused by plastic waste and electromagnetic radiation. Herein, poly(lactic acid) (PLA)/carbon nanotubes (CNTs) composites were prepared through a melt blending method. By adding a small amount of poly(D-lactic acid) to poly(L-lactic acid) (PLLA), the EMI shielding performance of the composites was improved because an enhanced viscoelasticity and suitable crystallinity could help to construct fine CNT conductive networks. When the PDLA content was 2 wt%, the EMI shielding effectiveness (SE) of the PLLA-2PDLA-10CNTs reached 27.1 dB at 26.5 GHz. Based on these findings, a green supercritical CO2 foaming method was employed to prepare lightweight PLLA/PDLA/CNTs composites. For the PLLA-2PDLA-10CNTs foams, when the expansion ratio was 1.24, the EMI SE was 20.1 dB at 26.5 GHz. In addition, the EMI shielding mechanism of the foams was dominated by absorption. This paper provides a facile way to prepare lightweight and environmentally friendly materials for EMI shielding applications.

Multilayer structured CNF/rGO aerogels and rGO film composites for efficient electromagnetic interference shielding

The development of efficient electromagnetic interference (EMI) shielding materials with high electromagnetic waves (EMWs) absorption capacity is of great significance to alleviate secondary EMWs pollution. Herein, multilayered composites were prepared by stacking cellulose nanofibril (CNF)/reduced graphene oxide (rGO) aerogels and rGO film together. The porous aerogels and the dense film serve as the EMWs absorbing layer and reflecting layer, respectively. When the EMWs enter the multilayer composites, they go through the process of absorption-reflection-reabsorption, resulting in a high EMI shielding effectiveness (SE) of ~32 dB. Furthermore, both experimental and theoretical analyses were adopted to explore the effect of arrangement order of CNF/rGO aerogels on EMI shielding performance. The results indicate that composites with progressively higher graphene content exhibit a higher EMWs absorption capacity at the same total EMI SE. This work offers a feasible design for improving EMWs absorption without affecting the overall EMI shielding performance of the material.

Fabrication of carbonized spent coffee grounds/graphene nanoplates/cyanate ester composites for superior and highly absorbed electromagnetic interference shielding performance

• Carbonized spent coffee grounds were used in EMI shielding field. • Superior and highly absorbed EMI shielding effectiveness was achieved. • The incorporation of C-SCG with a porous structure promotes a higher EMW absorption. • The prepared composites exhibit low reflectivity. The conductive polymer composites (CPCs) with highly efficient electromagnetic interference (EMI) shielding effectiveness (SE) are always accompanied with excessive reflectivity, which would cause serious secondary EMI pollution. In this regard, the significant reduction of EMI reflection of CPCs to alleviate secondary pollution is deemed to be very important. Herein, a promising cyanate ester (CE) based composite was successfully fabricated by compounding carbonized spent coffee grounds (C-SCG) and graphene nanosheets (GNSs) via a facile solution blending followed by a hot-pressing method. Benefiting from the porous structure of C-SCG and the layered structure of GNSs, a three-dimensional (3D) multi-interface conductive network in the CE was easily constructed. The EMI SE of the resultant 9 wt% C-SCG/CE composite (C9) is 15.38 dB and dramatically enhanced to 31.09 dB with the presence of 3 wt% GNSs. The remarkable enhancement is mainly attributed to the formation of the efficient conductive pathways as well as the well-dispersion of the incorporated fillers. Meanwhile, the absorption-dominated shielding mechanism in the prepared composites gets benefit from the synergistic effect of porous C-SCG and lamellar GNSs, which effectively captures and attenuates electromagnetic waves. These encouraging findings extend the practical applications of porous biocarbon materials in EMI shielding field.

Ultrahigh and Tunable Electromagnetic Interference Shielding Performance of PVDF Composite Induced by Nano-Micro Cellular Structure.

Lightweight and efficient electromagnetic interference (EMI) shielding materials play a vital role in protecting high-precision electronic devices and human health. Porous PVDF/CNTs/urchin-like Ni composites with different cell sizes from nanoscale to microscale were fabricated through one-step supercritical carbon dioxide (CO2) foaming. The electrical conductivity and electromagnetic interference (EMI) shielding performance of the composites with different cell sizes were examined in detail. The results indicated that the nanoscale cell structure diminishes the EMI shielding performance of the composite, whereas the microscale cell structure with an appropriate size is beneficial for improving the EMI shielding performance. A maximum EMI shielding effectiveness (SE) of 43.4 dB was achieved by the composite foams which is about twice that of the solid composite. Furthermore, as the supercritical CO2 foaming process reduces the density of the composite by 25–50%, the EMI SSE (specific shielding effectiveness)/t(thickness) of the composite reaches 402 dB/(g/cm2), which is the highest value of polymer foam obtained to the best of the authors’ knowledge. Finally, compression tests were performed to show that the composites still maintained excellent mechanical properties after the supercritical CO2 foaming process.

Flexible and Conductive Cellulose Composite Paper for Highly Efficient Electromagnetic Interference Shielding

AbstractDeveloping highly efficient electromagnetic interference (EMI) shielding materials with outstanding mechanical properties are urgently desirable for portable device hardware and flexible electronic devices. Herein, a highly conductive and flexible silver nanowires/graphene nanosheets/cellulose (AgNWs/GNSs/cellulose) composite paper with particular three‐layered structures is fabricated via vacuum assisted filtered and coating method. The prepared composites exhibit excellent EMI shielding property due to the unique layered structure. By changing the order of the conductive layers, the overall shielding performance can be further improved. An outstanding EMI shielding effectiveness (SE) of 53.3 dB is achieved with a thickness of only 0.17 mm. The composites show prominent bending resistance, which is proved by 1000 times of repeated bending leading to no obvious changes in structure. Moreover, the prepared composites exhibit excellent mechanical properties. Therefore, it is expected that this work will open up a facile strategy for exploiting materials with excellent EMI shielding properties and mechanical performance.

Multifunctional and corrosion resistant poly(phenylene sulfide)/Ag composites for electromagnetic interference shielding

Lightweight, multifunctional and highly efficient electromagnetic interference (EMI) shielding polymer composites with reliable EMI protection, efficient heat dissipation, excellent fire safety, and corrosion resistance are highly desired for next-generation electronic devices and high-power electronic communication technologies. However, developing robust and multifunctional conductive polymer shielding composites to meet stringent requirements when in harsh application environments remains a great challenge. Herein, a multi-functional and highly efficient EMI shielding poly(phenylene sulfide) (PPS) composite with a perfect 3D silver (Ag) conductive network and enhanced interfacial connection is fabricated through a unique silver-sulfur coordination reaction-induced in situ interfacial enhancement approach. The prevalent silver-sulfur coordination reaction between the PPS matrix and 3D Ag network provides the Ag/PPS composite with strong interfacial interaction and a reliable conductive network, leading to superior electrical conductivity, ultra-efficient EMI shielding effectiveness (87.8 dB), excellent thermal conductivity (1.15 Wm-1K−1), remarkable corrosion resistance and satisfactory mechanical properties (~60 MPa) at very low Ag contents. Moreover, the multi-functional shielding composite also exhibits marvellous anti-friction and wear-resistant performance along with excellent fire resistance and antibacterial properties. Therefore, the silver-sulfur coordination reaction-induced in situ interfacial enhancement during facile thermal compression moulding creates a multi-functional and robust EMI shielding composite, which is promising for conferring ideal EMI protection to next-generation electronics in complex application environments.

Flexible and lightweight Ti3C2Tx MXene/Fe3O4@PANI composite films for high-performance electromagnetic interference shielding

Ti3C2Tx MXene has been explored as an efficient electromagnetic interference (EMI) shielding material because of its high electrical conductivity, large specific surface area, rich surface defects, and abundant functional groups. Herein, core-shell Fe3O4@PANI composites were prepared, followed by the preparation of a flexible and lightweight Ti3C2Tx/Fe3O4@PANI composite film with sandwich intercalation structure by vacuum-assisted filtration, using Ti3C2Tx MXene as a matrix material. The ultrathin composite film with a Ti3C2Tx nanosheets to Fe3O4@PANI weight ratio of 12:5 reached a maximum EMI shielding effectiveness (SE) value of 58.8 dB at a thickness of only 12.1 μm. This is much higher than the SE of pure conductive Ti3C2Tx films of the same thickness. After adjusting the film thickness by increasing the concentration of Ti3C2Tx, an SE of 62 dB was achieved at a thickness of 16.7 μm. The ultrathin Ti3C2Tx/Fe3O4@PANI films exhibit potential for application in packaging, wearable electronic equipment, and military fields. Moreover, they provide insight into the preparation of lightweight and progressive electromagnetic shielding materials.