Superior Electromagnetic Interference Shielding Research Articles

Design of polyimide/carbon nanotube@Ag@polyimide/graphene composite aerogel for infrared stealth and electromagnetic interference protection

CHATGPT artificial intelligence is taking the world by storm, and countless electronic devices will generate massive amounts of electromagnetic interference (EMI). Hence, there is a pressing demand for materials exhibiting high thermal conductivity and superior EMI shielding effectiveness (SE). Thus, we construct a polyimide/carbon nanotube@Ag@polyimide/graphene (PCAPG) composite aerogel with porous, layered, and homogeneous structures in one, which provides a new idea for the multi-interface polarization interaction and special structure of anti-EMI materials. PCAPG has high thermal conductivity of ∼ 0.259 W (mK)-1 at 25 °C, excellent EMI SE of ∼ 90.28 dB and specific shielding effectiveness (SSE) of ∼ 940.42 dB cm3 g−1. The synergistic EMI attenuation mechanism of the PCAPG composite structure is analyzed using an aerogel unit. This composite aerogel provides a viable solution for infrared stealth, promoting heat dissipation from electronic components and reducing electromagnetic interference.

Roll-to-roll joule-heating to construct ferromagnetic carbon fiber felt for superior electromagnetic interference shielding

The effective safeguard from electromagnetic radiation damage via electromagnetic interference shielding (EMI) materials is crucial for diverse applications, especially in modern aerospace, medical, and human body protection endeavors. Despite great efforts have been made to surmount challenges encompassing scalability, sustainability and cost, the integrated and continuous production of large-area electromagnetic shielding materials remains unsolved for industrial-scale demands. Herein, we develop a cascaded methodology involving spray loading and Joule-heating for fabricating hybrid EMI fabric with superior efficiency, where ferromagnetic Fe3O4 nanoparticles are further successfully in situ deposition on ultralight carbon fiber felt (Fe3O4/FePc@CFF) in a roll-to-roll (R2R) manner. Fe3O4/FePc@CFF characterized by a surface density of only 64.76 g/m2, achieves specific shielding effectiveness per unit thickness (SSE/t) remarkable values of 9604 dB cm2 g−1 and 10947 dB cm2 g−1 within the X-band and Ku-band, respectively. Considering the high compatibility with assembly on flow line production, this research offers substantial development potential for further design and advancement of pivotal materials in the realm of electromagnetic protection.

Highly durable hollow sandwich MXene/h-AgNWs/ANF composite films for exceptional electromagnetic interference shielding performance

Multi-functional electromagnetic interference (EMI) shielding materials are crucial for advanced electronic devices, requiring low thickness, exceptional shielding performance, and stability, especially in extreme conditions. In this study, the hollow sandwich MXene/h-AgNWs/ANF (AMAgMA) composite films were fabricated via template sacrificing method and layer-by-layer vacuum assisted filtration. Specifically, the hollow MXene was created using PMMA as the template, together with AgNWs for the conductive layer, while ANF provided stability and high temperature resistance as the protective layer. The optimized EMI shielding efficiency (SE) reached 88.2 dB for a film thickness of 93 μm, with an SSE/t value of 18160 dB cm2·g−1, which was attributed to the hollow structure and continuous double conductive network design. Remarkably, EMI SE of the films maintained even after 70 days of exposure to oxidation, acid, alkali, salt, and ultrasonic treatment thanks to the sandwich design. Additionally, the composite films displayed excellent heat transfer and thermal stability (530 °C), alongside notable flame retardancy and self-extinguishing properties. The superior EMI shielding performance and stability in extreme environments suggest a promising application potential in advanced electronics.

Environmentally tolerant conductive organohydrogel toward superior electromagnetic interference shielding and human motion detection

Environmentally tolerant conductive organohydrogel toward superior electromagnetic interference shielding and human motion detection

Laser-forged transformation and encapsulation of nanoalloys: pioneering robust wideband electromagnetic wave absorption and shielding from GHz to THz

The emergence of the internet of things has promoted wireless communication’s evolution towards multi-band and multi-area utilization. Notably, forthcoming sixth-generation (6G) communication standards, incorporating terahertz (THz) frequencies alongside existing gigahertz (GHz) modes, drive the need for a versatile multi-band electromagnetic wave (EMW) absorbing and shielding material. This study introduces a pivotal advance via a new strategy, called ultrafast laser-induced thermal-chemical transformation and encapsulation of nanoalloys (LITENs). Employing multivariate metal-organic frameworks, this approach tailors a porous, multifunctional graphene-encased magnetic nanoalloy (GEMN). By fine-tuning pulse laser parameters and material components, the resulting GEMN excels in low-frequency absorption and THz shielding. GEMN achieves a breakthrough of minimum reflection loss of −50.6 dB in the optimal C-band (around 4.98 GHz). Computational evidence reinforces GEMN’s efficacy in reducing radar cross sections. Additionally, GEMN demonstrates superior electromagnetic interference shielding, reaching 98.92 dB under THz band (0.1–2 THz), with the mean value result of 55.47 dB. These accomplishments underscore GEMN’s potential for 6G signal shielding. In summary, LITEN yields the remarkable EMW controlling performance, holding promise in both GHz and THz frequency domains. This contribution heralds a paradigm shift in EM absorption and shielding materials, establishing a universally applicable framework with profound implications for future pursuits.

Asymmetric multilayered cellulose nanofiber composite membranes with electrical-magnetic dual-gradient architectures towards excellent electromagnetic interference shielding performance

The structural design strategies of MXene-based nanocomposites have demonstrated critical significance for electromagnetic interference (EMI) shielding applications. Herein, novel asymmetric multilayered cellulose nanofiber/multiwalled carbon nanotube@ferroferric oxide/MXene (CNF/MWCNT@Fe3O4/MXene) composite membranes with electrical-magnetic dual-gradient structures were prepared via layered-by-layered self-assembly strategy. Briefly, CNF/MWCNT@Fe3O4 layers are designed as the negative gradient absorption layers which provide dielectric/magnetic double loss. Meanwhile, MXene layers serve as the positive gradient reflection layers which generate multiple reflections and conduct loss. Thus, gradient multilayered CNF/MWCNT@Fe3O4/MXene composite membranes exhibit a total electromagnetic interference shielding effectiveness (EMI SET) of 73.20 dB at the thickness of 180 μm and R-value of 0.99934 in the X-band. Furthermore, the asymmetric gradient multilayer composite membrane reveals a superior EMI shielding performance in comparison with that of homogeneous multilayered composite membranes. When electromagnetic waves (EMWs) pass through the gradient multilayered CNF/MWCNT@Fe3O4/MXene composite membrane, the rational asymmetric gradient multilayered structures contribute to a “gradually decreasing absorption-gradually increasing reflection” shielding mechanism. Thereby, the design strategy of asymmetric electrical-magnetic dual-gradient structures is advantageous in enhancing the EMI shielding ability of polymeric composites.

Multifunctional properties of carbon nanotube yarn/aerogel laminate composites

This work explores the multifunctional performance of scalable carbon nanotube (CNT) yarn laminate composites. Tensile, thermal, electrical, and electromagnetic interference (EMI) shielding properties are compared to state-of-the-art unidirectional IM7/5250-4 carbon fiber composite (CFRP). CNT laminates achieved a specific tensile modulus of 249.7 ± 22.3 GPa/(g/cm3), which is over double the specific modulus of the CFRP, while maintaining a specific tensile strength of 1.88 ± 0.17 GPa/(g/cm3) which is comparable to the CFRP. CNT yarn laminates demonstrated superior thermal transport properties, with in-plane thermal conductivity of 75.78 ± 14.3 W/mK, over 13 times higher than the CFRP. CNT yarn laminates were also superior in electrical conductivity, achieving a longitudinal conductivity of 5359 ± 417 S/cm and transverse conductivity of 36.87 ± 2.55 S/cm. This translated to superior EMI shielding properties, achieving over 100 dB in the X-band, which is nearly double that of the CFRP. Incorporating CNT aerogel interwoven between CNT yarns reduced the large property variance observed in the measurements, demonstrating a multifunctional material with tensile, thermal, electrical, and EMI properties superior to the CFRP, while potentially mitigating the scalability challenges inherent to CNT nanomaterials.

Bacterial cellulose-based composite films with liquid metal/graphene synergistic conductive pathways for superior electromagnetic interference shielding and Joule heating performance

Modern integrated electronics are in great demand for high-performance electromagnetic interference (EMI) shielding materials with exceptional mechanical properties. Liquid metal (LM) has demonstrated great potential in EMI shielding by its superior electrical conductivity. However, its real-world EMI application is limited by the poor compatibility, insulating oxide shells, and unpredictable leakage. Here, graphene oxide (GO) is used to encapsulate LM to form LM@GO microdroplets dispersion, and bacterial cellulose (BC) is applied to construct a biocompatible fabric network. Moreover, GO is in-situ reduced by hydrazine vapor, which generates synergistic LM/reduced graphene oxide (rGO) conductive pathways with the aid of roll-in process, obtaining flexible LM/rGO/BC (LGB) composite film with outstanding electrical conductivity of 4.5 × 104 S/m and exceptional shielding effectiveness of 64.0 dB. The rGO sheets and BC network demonstrate layered structure after roll-in process, effectively impeding the leakage and oxidation of LM and achieving a tensile strength up to 62.9 MPa of LGB films. Meanwhile, the LGB films exhibit exceptional Joule heating performance, and the stable surface temperature reaches 110 °C with high stability and reliability when the applied voltage is 4 V. This work provides a feasible engineering approach to prepare LM-based films for applications in EMI shielding and wearable electronics.

Flexible, hydrophobic, and robust composite films with sandwich structure for electromagnetic interference shielding and Joule heating

Electromagnetic interference (EMI) shielding materials with favorable flexibility, robustness, and multipurpose capabilities are urgently desired for smart wearable devices. Herein, flexible PDMS/cellulose nanofiber/Ag nanowire composite films with sandwich structures were successfully fabricated by a facile method. First, silver nanowires (AgNWs) were uniformly stacked in the upper part of the cellulose gel using a controlled two-step vacuum-assisted filtration; next, AgNWs were tightly embedded in the cellulose matrix by a hot-pressing strategy; finally, a hydrophobic protective layer, PDMS, was introduced. The water contact angle (WCA) of composite films could reach 121°. Compared with uniformly mixed films, AgNWs deposited only on the surface of the matrix allowed the conductivity to reach 381 S/cm at a low weight fraction of AgNWs (6 wt%). Thanks to such excellent conductivity, the composite films exhibited superior EMI shielding effectiveness (49 dB) at only 40 μm thickness, and Joule heating performance, i.e., the surface temperature reached 111.3 °C at 1.5 V driving voltage. It was worth noting that after bending and peeling damage, the WCA and EMI shielding effectiveness of composite films were not significantly impacted due to the hot-pressing strategy and hydrophobic surface protection. The robust composite films show huge application potential in the wearable electronics field.

Lightweight graphene foam composites with enhanced electrical conductivity and microwave absorption for electromagnetic interference shielding

Next-generation flexible electronics call for high-performance electromagnetic interference (EMI) shielding materials with lightweight and multifunctionality. Here, the chemical vapor deposition (CVD) graphene foam (GF) composites, containing flexible polymer matrix and magnetic Fe3O4 nanoparticles, are reported. The systematic manipulation of GF growth condition and the content of Fe3O4 reveals the effect of graphene thickness and integration of Fe3O4 on improving the electromagnetic shielding performance of composites. Owing to abundant internal interfaces, high conductivity from the three-dimensional interconnected graphene, and magnetic loss from Fe3O4, the ternary composites exhibit substantial improvement in microwave absorption, resulting in a superior EMI shielding effectiveness (SE) and absolute EMI SE up to 71 dB and 3641 dB·cm2/g, respectively, at a low density of 0.65 g/cm3 and minimal thickness of 0.3 mm. Moreover, the flexible composites display great EMI shielding stability after repeatedly bending, validating the composites as promising materials for practical applications in aerospace and flexible electronics.

A Sandwich Structural Filter Paper-AgNWs/MXene Composite for Superior Electromagnetic Interference Shielding.

A thin, lightweight and flexible electromagnetic interference (EMI) shielding paper composite is an urgent need for modern military confrontations. Herein, a sandwich-structured EMI shielding paper composite with an easy pavement consisting of a filter paper layer, middle AgNWs/MXene layer, and polyvinyl butyral (PVB) layer was constructed by vacuum-assisted filtration, spraying and air-drying. The middle AgNWs/MXene compound endowed the filter paper with excellent electrical conductivity (166 S cm-1) and the fabricated filter paper-AgNWs/MXene-PVB composite exhibits superior EMI shielding (30 dB) with a 141 μm thickness. Remarkably, the specific EMI shielding effectiveness (SSE/t) of the filter paper-AgNWs/MXene-PVB composite reached 13,000 dB cm2 g-1 within the X-band frequency range. This value represents one of the highest reported for cellulose-based EMI shielding materials. Therefore, our sandwich-structured filter paper composite with superior EMI shielding performance can be used in the medical and military fields.

Regulated orientation and exfoliation of flaky fillers by close packing structures in polymer composites for excellent thermal conduction and EMI shielding

Efficient heat dissipation and electromagnetic interference (EMI) shielding are essential demands on packaging intensively integrated circuits in advanced electronics. Multicompetent polymer composites with thermal conduction and EMI shielding capacity have attracted tremendous interest in the material science community. Herein, we report the preparation of thermally conductive polymer composites with superior EMI shielding effectiveness (SE) by building a 3D interconnected conductive network under close-packing circumstances. The build of the 3D network relies on the coordinated stacking of flaky and spherical fillers, where the asymmetric graphite flakes (FG) are confined in the interstitial regions of the close-packing structures of hollow glass microspheres (HGμS). The “rigid” close-packing structure of HGμS inhibits the in-plane orientation of FG along the flow direction during melt processing and facilitates the exfoliation of FG under external forces producing a conductive network with enhanced interconnectedness. The model system comprised of thermoplastic polyurethane (TPU), FG and HGμS has attained in-plane and through-plane thermal conductivity of 20.54 W m−1 K−1 and 6.55 W m−1 K−1 with 30 vol% FG (while maintaining a low mass density of 1.15 g cm−3, identical to neat TPU). Meanwhile, a high EMI SE of 69 dB has been achieved at a thickness of 1 mm.

Mechanically robust and multifunctional Ti3C2Tx MXene composite aerogel for broadband EMI shielding

Because of its high electrical conductivity and low density, Ti3C2Tx MXene aerogel is thought to be a promising electromagnetic interference (EMI) shielding material. However, it is suffering from high reflection shielding and poor mechanical strength, which naturally hinders its practical application. Herein, we constructed PDMS-encapsulated Fe3O4/multi-walled carbon nanotubes (MWCNTs)/Ti3C2Tx MXene aerogel by combining the bi-directional freeze-drying technique with vacuum impregnation. The lamellar porous architecture and rational components endow the PDMS-encapsulated composite aerogel with superior EMI shielding properties in the X- and Ku-bands. Specifically, the optimal total shielding effectiveness (SET) of the PDMS-encapsulated composite aerogel (3 mm) could reach 43.6 dB, whereas the corresponding reflection shielding effectiveness (SER) is only 7 dB (approximately 16.7 % of SET). The shielding mechanism was also comprehensively disclosed. Simultaneously, contributed by the synergistic effect of lamellar porous structure and PDMS, the PDMS-encapsulated composite aerogel possesses satisfactory compressive strength (28.62 MPa) and tensile strength (1.67 MPa). Additionally, the PDMS-encapsulated composite aerogel also exhibits promising applications in thermal insulation.

A continuous interfacial bridging approach to fabricate ultrastrong hydroxylated carbon nanotubes intercalated MXene films with superior electromagnetic interference shielding and thermal dissipating properties

A continuous interfacial bridging approach to fabricate ultrastrong hydroxylated carbon nanotubes intercalated MXene films with superior electromagnetic interference shielding and thermal dissipating properties

Regulating synergistic micro-nano pore structure of CNT sponge to control EMI shielding performance

The aggregation in high-content carbon nanotube reinforced silica carbide composites (CNT/SiC) imposed constraints for further large-scale industrial applications. This study established a synergistic micro-nano pore structure by assembling CNT bundles to fabricate the CNT sponge preform, and then the SiC matrix was in-situ deposited by chemical vapor infiltration method, which facilitates composites with high density and exceptional properties. The pore size distribution and pore area can be regulated by simply adjusting the compression ratios (CRs) of the as-assembled CNT sponge. Samples with CR of 50 % exhibited noteworthy densification, significantly reduced porosity, and a remarkable 163.54 % extra increase in compression strength compared to uncompressed ones. Additionally, the CNT/SiC composites displayed excellent oxidation resistance and demonstrated improved electromagnetic interference (EMI) shielding performance, which exhibited a substantial increase with higher CRs. These findings underscore the significance of employing appropriate multi-level porosity in CNT preforms to fabricate advanced ceramic matrix composites with superior EMI shielding capabilities.

Self‐Destructible Electromagnetic Interference Shielding Films

AbstractIn response to the increasing utilization of communication technology, there is a growing need for electromagnetic interference (EMI) shielding materials to adapt to diverse application scenarios. In this study, the self‐destructible EMI shielding films (SEFs) that possess the unique capability to reduce conductivity and shielding efficiency through temperature elevation are introduced. The SEFs effectively fulfill the requirement of triggering EMI shielding failure under specific conditions, which can be achieved by simply spraying a mixture of thermally expandable microspheres (TEMs), conductive fillers, and resin substrates. The segregated structures resulting from the incorporation of TEMs confer exceptional electrical conductivity and superior EMI shielding performance at low conductive filler content. When the ambient temperature surpasses the glass transition temperature of the TEM shell, the thermally expandable characteristics cause a disruption in the conductive path of the SEFs, leading to a significant decline in shielding effectiveness. Additionally, the SEFs exhibit outstanding Joule heating effects (90 °C) at low voltage (1.5 V) within a brief time frame (10 s). Importantly, when employed as Joule heaters, the SEFs possess an intrinsic safety mechanism that automatically ceases operation in the event of circuit overload, thus minimizing any potential risks.

Adjustable Ti2C3Alx-based segregated composite network for enhanced electromagnetic shielding and fire safety

With the rapid development of communication technology and portable electronic devices, the demand for the design of electronic devices with superior electromagnetic interference shielding and fire safety performance is increasing. Herein, epoxy resins (EPs) with typical segregated networks were designed by emulsion polymerization and adhesion self-assembly strategies and novel polyphosphonitrile microspheres (PZS) synthesized by precipitation polymerization were used to improve the fire safety of EP composites. It is worth noting that the oil-water (EP to water) ratio in emulsion polymerization is closely related to the microscopic morphology of the segregated network. A smaller ratio of EP to water results in more paths for electrical charge transfer through the EP composites. As a result, EP/PT-3 with a minimum oil-to-water ratio exhibits a high EMI SE (electromagnetic interference shielding effectiveness) in the X-band ranging from 40.12 to 40.30 dB at a loading of 7.20 vol% Ti3C2Alx. Besides, the synergistic action of the adjustable Ti3C2Alx network with PZS endows EP superior flame retardant performance. Compared with EP, the PHRR and THR values of EP/PT-3 are down 55.7 % and 72.6 %, respectively. There is no doubt that EP/PT-3 has provided a new route for the preparation of Ti3C2Alx-based electromagnetic shielding and fireproof materials.

Co-cured GNP films with liquid thermoplastic/glass fiber composites for superior EMI shielding and impact properties for space applications

In this study, we explored the potential of manufacturing high concentration Graphene Nano-Platelet (GNP) films using liquid thermoplastic Elium® resin. A novel approach was adopted to co-cure manufactured GNP films with glass fiber reinforced Elium® composites to achieve superior electromagnetic interference (EMI) shielding and impact properties. The flexible GNP films were prepared using different concentrations (2 and 5 wt%) of GNPs mixed within the Elium® resin. The glass fiber/Elium® composites were prepared by infusing the liquid thermoplastic resin and simultaneously co-curing the manufactured GNP films on a heated resin infusion tool surface. The GNP films were placed at different locations within the composite i.e., as an outer layer for EMI shielding and within the laminate for impact performance. After resin infusion, the impact test specimens were hot pressed above the glass transition temperature of the Elium® resin for better dispersion of GNPs within the composite. The manufactured composites exhibited excellent EMI shielding effectiveness of more than 32 dB and impact energy absorption, strength, and stiffness increase in the order of 105 %, 48 %, and 45 % respectively, when compared with pristine Glass Fiber Reinforced Polymer Composites (GFRPCs). The results reveal the remarkable potential of the proposed manufacturing technique to achieve superior and tailorable EMI shielding and impact performance of GFRPCs without issues of agglomeration of GNP particles at high concentrations for different space-related applications.

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.

Mechanically strong, flexible, and flame-retardant Ti3C2Tx MXene-coated aramid paper with superior electromagnetic interference shielding and electrical heating performance

Undesirable electromagnetic interference (EMI) created by modern electronic devices has detrimental effects on the performance of high-precision electronic devices, information security, and human health. Therefore, lightweight, flexible, robust, and easy-to-fabricate EMI shielding materials with integrated functions are highly desirable to combat electromagnetic pollution. Herein, we report a scalable and facile strategy to prepare a flexible Ti3C2Tx MXene-coated aramid paper (MAP) with high-efficiency EMI shielding and excellent electrical heating performance. The intertwined network by aramid fibers endows the aramid paper (AP) with superior mechanical properties. After selectively single/dual coating with MXene onto AP, the MAP maintains a superior tensile strength of 73.6 MPa and enormous folding endurance of 4156 times. Owing to the exceptional electrical conductivity of MXene, the MAP with a relatively low MXene content (∼9.0 wt%) exhibits excellent overall performance with an EMI shielding effectiveness (SE) of 38 dB and SE/t of 422.2 dB mm−1. It’s noteworthy that the EMI SE of the MAP remains almost unchanged (37.4 dB) even after experiencing 5,000 repeated bending cycles. Additionally, the MAP shows satisfactory Joule electric-heating capability (a heating temperature rise of 130 °C at a low driving voltage of 5 V) and excellent flame-retardancy. This work provides a feasible strategy for large-scale production of flexible EMI shielding paper with multifunctional properties for future wearable facilities.