Exceptional Electromagnetic Interference Shielding Research Articles

Vertically aligned carbon fiber/polydimethylsiloxane composites prepared by lyophilization with exceptional thermal conductivity and electromagnetic interference shielding performance

Composites with high thermal conductivity and exceptional electromagnetic interference (EMI) shielding properties are crucial for ensuring the long-term stability of electronic devices. One-dimensional carbon fibers (CFs) stand out as promising materials due to their excellent thermal and electrical conductivity. However, the anisotropic nature of CFs limits the overall electrical and thermal conductivity of the composite, thus impeding its practical application. To address this limitation, we investigated the effect of different freezing methods on CF orientation using the ice template method. Subsequently, CF-150/PDMS and CF-250/PDMS composites with varying average lengths of CFs were prepared using the unidirectional freezing technique. We studied the influence of CF content and average length on the anisotropic thermal conductivity and EMI shielding properties of the composites. The CF-250/PDMS composite, with a CF content of 15.71 vol%, exhibits a remarkable thermal conductivity of 9.07 W·m−1·K−1 and a low thermal resistance of 2.61 °C·cm2‧W−1. The thermal conductive mechanism of CF/PDMS composites was simulated by thermal conduction model and finite element analysis. Furthermore, it demonstrates longitudinal electromagnetic interference shielding effectiveness (EMI SE) reaches up to 39.66 dB, while the transverse EMI SE reaches up to 52.55 dB. The vertically aligned CF/PDMS composites exhibit significant potential for a range of applications in thermal management and EMI shielding.

Layer-by-layer assembly of boron arsenide and copper nanoflake-based aramid nanofibers for thermoconductive electromagnetic interference shielding materials with superior mechanical flexibility and flame retardancy

Flexible and wearable electronics represent an emerging frontier, but realizing their potential requires addressing challenges like electromagnetic interference (EMI) shielding, electrical insulating thermal management, and mechanical flexibility. Layer-by-layer structure with alternating conductive and insulating layers offers a promising solution. In this work, we fabricated layer-by-layer structured papers combining boron arsenide (BA) as insulating layers and two-dimensional copper nanoflake (CuF) as conductive layers based on aramid nanofiber (ANF) film via alternating vacuum filtration. The resultant paper (BA4/CuF3) consists of 3 layers of CuF (50 wt%) based ANF (CuF@ANF) conductive layers sandwiched between 4 layers of BA (50 wt%) based ANF (BA/ANF) insulating layers providing exceptional EMI shielding effectiveness (SE) up to 52 dB in the X-band frequency, and in-plane thermal conductivity up to 32.8 W/mK. Meanwhile, the composite papers also demonstrate excellent mechanical flexibility, with the BA4/CuF3 papers exhibiting a tensile strength of 92.38 MPa and EMI SE above 50 dB. Moreover, the composites impart thermal stability up to 500 °C and reduce flammability. The concurrent enhancement of EMI shielding, thermal conductivity, and mechanical properties confirms the potential of layer-by-layer BA/CuF papers for next-generation flexible electronics demanding electromagnetic protection and thermal management.

2D/0D multiscale interfacial engineering of carbon fiber composites for simultaneous achieving high mechanical and electromagnetic interference shielding properties

AbstractIn the face of escalating electromagnetic pollution, it is urgently needed to expedite the development of innovative carbon fiber reinforced polymer (CFRP) composites that not only demonstrate superior mechanical properties as well as durability but also boast exceptional electromagnetic interference shielding (EMI) performance. However, given the absence of robust interface interactions and the lack of an outstanding nanostructured conductive network, there remains a need to further elevate the overall performance of CFRP composites. Herein, a highly continuous conductive network by integrating 2D MXene and 0D Ag nanoparticles with strong interlayer interactions was constructed through point‐to‐plane conductive modes, facilitated by polydopamine (PDA). Thanks to the excellent electromagnetic wave loss and the unique multi‐dimensional structure arising from the optimizing interfacial engineering, the EMI shielding effectiveness of the modified CF‐PDA‐M‐Ag/EP composite achieved a remarkable 45.9 dB, obtaining a 99.5% enhancement compared with the neat CF/EP. The synergistic effect resulting from the multi‐dimensional structure and strong interaction can improve the interfacial shear strength (IFSS), interlaminar shear strength (ILSS) and flexure strength of the composite up to 81.9, 85.8 and 864.6 MPa, respectively, far superior to the unmodified composite materials. This research provides a dependable and convenient approach for exploiting high‐performance CFRP composites with intriguing electromagnetic interference (EMI) shielding properties.Highlights An optimizing multifunctional 2D/0D interface for carbon fiber was designed. A highly conductive network via the point‐to‐plane conductive mode. The EMI shielding effectiveness of the composite reached up to 45.9 dB.

Conducting polymer hollow nanostructures by surfactant-free Ouzo emulsion for an exceptional EMI shielding performance

Hollow or partially collapsed bowls of conducting polymers, such as poly(3,4-ethylenedioxythiophene) (PEDOT), polypyrrole (Ppy), polyaniline (PANI), and polythiophene (PT), have successfully been synthesized by surfactant-free Ouzo emulsion. The stable Ouzo region has been identified based on three-component phase diagram of FeCl3·6H2O as an oxidant, acetone as solvent, and toluene as anti-solvent, respectively. The solvent/oxidant mixture forms emulsion droplets in anti-solvent medium spontaneously without any surfactant. It is the very first report on the generation of Ouzo state in the chemical oxidative polymerization systems of conducting polymers. Cast thin film of the synthesized conducting polymer hollow nanostructures was infiltrated with commercial PEDOT:PSS solution for the formation of composite structures, where the highly conductive networks of PEDOT:PSS ensures electrical conductivity. In the meanwhile, the embedded hollow nanostructures enable multiple scattering of incident electromagnetic wave. A thin (∼6 μm) composite film shows exceptional electromagnetic interference (EMI) shielding effectiveness of ∼75 dB in X-band (8–12 GHz). Furthermore, thanks to low density of hollow conducting polymer nanostructures, thickness-normalized specific shielding effectiveness (SSE/t) shows the highest value compared to other materials published in literature. The hollow nanostructures of conducting polymers, formed using surfactant-free Ouzo emulsion, may find broader applications thanks to its simple and contaminant-free nature.

Sn Whiskers from Ti2 SnC Max Phase: Bridging Dual-Functionality in Electromagnetic Attenuation.

In the ever-evolving landscape of complex electromagnetic (EM) environments, the demand for EM-attenuating materials with multiple functionalities has grown. 1D metals, known for their high conductivity and ability to form networks that facilitate electron migration, stand out as promising candidates for EM attenuation. Presently, they find primary use in electromagnetic interference (EMI) shielding, but achieving a dual-purpose application for EMI shielding and microwave absorption (MA) remains a challenge. In this context, Sn whiskers derived from the Ti2 SnC MAX phase exhibit exceptional EMI shielding and MA properties. A minimum reflection loss of -44.82dB is achievable at lower loading ratios, while higher loading ratios yield efficient EMI shielding effectiveness of 42.78dB. These qualities result from a delicate balance between impedance matching and EM energy attenuation via adjustable conductive networks; and the enhanced interfacial polarization effect at the cylindrical heterogeneous interface between Sn and SnO2 , visually characterized through off-axis electron holography, also contributes to the impressive performance. Considering the compositional diversity of MAX phases and the scalable fabrication approach with environmental friendliness, this study provides a valuable pathway to multifunctional EM attenuating materials based on 1D metals.

Improved electromagnetic interference shielding performance of silicone rubber/CNTs composites by porous structure design via green supercritical CO2 foaming

In this study, the relationship between porous structure and electromagnetic interference (EMI) shielding performance of polymer foams is established. A green supercritical CO2 foaming technology is utilized to construct silicone rubber (PMVS)/carbon nanotubes (CNTs) foams with tunable porous structures (porosity, cell size, cell density and cell gradient structure). Notably, the introduction of moderate porosity (within 40 %) simultaneously enhanced the total EMI shielding effectiveness (SET) and absorption coefficient (A). PMVS/CNTs foam reached a maximum SET of 62.3 dB, a 35.4 % increase over solid PMVS/CNTs composite. Additionally, small-cell PMVS/CNTs foam shows a higher A under the same porosity, while large-cell foam exhibits higher SET. Moreover, gradient porous PMVS/CNTs, combining advantages of large and small cells, maintains a high A (78 %) and exhibits superior SET (52.7 dB), along with exceptional EMI shielding stability (with SET and A retaining 97.7 % and 99 %, respectively, after 1000 cycles of compression). This work provides a theoretical foundation for optimizing EMI shielding performance by regulating porous structures.

Large-Scale Fabrication of Tunable Sandwich-Structured Silver Nanowires and Aramid Nanofiber Films for Exceptional Electromagnetic Interference (EMI) Shielding.

The recent advancements in communication technology have facilitated the widespread deployment of electronic communication equipment globally, resulting in the pervasive presence of electromagnetic pollution. Consequently, there is an urgent necessity to develop a thin, lightweight, efficient, and durable electromagnetic interference (EMI) shielding material capable of withstanding severe environmental conditions. In this paper, we propose an innovative and scalable method for preparing EMI shielding films with a tunable sandwich structure. The film possesses a nylon mesh (NM) backbone, with AgNWs serving as the shielding coating and aramid nanofibers (ANFs) acting as the cladding layer. The prepared film was thin and flexible, with a thickness of only 0.13 mm. AgNWs can easily form a conductive network structure, and when the minimum addition amount was 0.2 mg/cm2, the EMI SE value reached 28.7 dB, effectively shielding 99.884% of electromagnetic waves and thereby meeting the commercial shielding requirement of 20 dB. With an increase in dosage up to 1.0 mg/cm2, the EMI SE value further improved to reach 50.6 dB. The NAAANF film demonstrated remarkable robustness in the face of complex usage environments as a result of the outstanding thermal, acid, and alkali resistance properties of aramid fibers. Such a thin, efficient, and environmentally resistant EMI shielding film provided new ideas for the broad EMI shielding market.

Self-Assembly of Binderless MXene Aerogel for Multiple-Scenario and Responsive Phase Change Composites with Ultrahigh Thermal Energy Storage Density and Exceptional Electromagnetic Interference Shielding

HighlightsThis work proposes a tactic for improving the efficiency of thermal energy conversion and expanding the application scenarios of phase change materials by constructing non-binder and oriented MXene-K+ aerogel.The prepared phase change composites (PCCs) can rapidly transform solar, electric, magnetic energy into latent heat for keeping warm, power generation, and thermal physiotherapy.Owing to the suggested tactic, the prepared PCCs achieves ultrahigh energy storage density and realize 99.9998% electromagnetic wave energy attenuation.

Ultra‐wideband electromagnetic interference shielding properties of parallel expanded graphite/Fe3O4 composites

AbstractThe rapid development of electronic devices in various fields has stimulated an increased demand for electromagnetic interference (EMI) shielding materials working in ultra‐wideband frequencies of gigahertz. However, the aggregation problem and single attenuation mechanism severely limit the broadband shielding applications of nanomaterials. To address these challenges, a novel composite of parallel expanded graphite (EG) embedded in the densified Fe3O4 matrix is designed and successfully synthesized through the in situ chemical coprecipitation followed by pressure sintering. This unique structure creates heterogeneous interfaces by combining the conductive EG and magnetic Fe3O4. The significant dielectric and magnetic loss then arise from conduction and polarization loss, as well as the eddy current and resonance effects. The multiple reflections of electromagnetic waves between the oriented EG sheets further cause the “absorb–reflect–reabsorb” effect that prolongs the propagation paths and enhances the dissipation of electromagnetic waves. Based on these multiple mechanisms over an ultrawide range of frequencies (8.2–40 GHz), the EG/Fe3O4 composites exhibit exceptional EMI shielding performance, with an average shielding effectiveness of 29.3 dB, indicating the potential for multifunctional EMI shielding applications.

Preparation of nano‐silver electromagnetic interference shielding functional coating on PC+ABS plastic via Ar/H2 mixed atmospheric pressure plasma jet

AbstractMetal coatings with micron thickness, high conductivity, and a unique structure that can provide exceptional electromagnetic interference (EMI) shielding performance to insulation substrates are highly desirable, especially if the production method is inexpensive, pollution‐free, and efficient. In this study, the Ar/H2 mixed atmospheric pressure plasma jet (APPJ) was utilized to reduce AgNO3 to produce PC + ABS substrates coated with silver nanoparticles (AgNPs). It was found that the low roughness AgNPs coating has a multilayer network structure, which could exhibit high conductivity and excellent EMI shielding effectiveness (SE). In conclusion, this method is an excellent choice for producing metal EMI shielding coating.

Rapid Fabrication of Flexible Cu@Ag Flake/SAE Composites with Exceptional EMIS and Joule Heating Performance.

High electromagnetic interference shielding (EMIS) effectiveness and good thermal management properties are both required to meet the rapid development of integrated electronic components. However, it remains challenging to obtain environmentally friendly and flexible films with high EMIS and thermal management performance in an efficient and scalable way. In this paper, an environmentally friendly strategy is proposed to synthesize multifunctional waterborne Cu@Ag flake conductive films using water as the solvent and silicone-acrylic emulsion (SAE) as a matrix. The obtained films show high electrical conductivity and exceptional EMI SE and electrothermal conversion properties. The EMI SE in the X-band is higher than 76.31 dB at a thickness of 60 μm owing to the ultrahigh electrical conductivity of 1073.61 S cm-1. The film warms up quickly to 102.1 °C within 10 s under a low voltage of 2.0 V. In addition, the shielding coating is sufficiently flexible to retain a conductivity of 93.4% after 2000 bending-release cycles with a bending radius of 3 mm. This work presents an alternative strategy to produce high EMIS effectiveness and Joule heating films for highly integrated and flexible electronic components in a green, scalable, and highly efficient way.

Multifunctional Flexible AgNW/MXene/PDMS Composite Films for Efficient Electromagnetic Interference Shielding and Strain Sensing.

With the rapid development of electronic information technology, composite materials with outstanding performance in terms of electromagnetic interference (EMI) shielding and strain sensing are crucial for next-generation smart wearable electronic devices. However, the fabrication of flexible composite films with dual functionality remains a significant challenge. Herein, multifunctional flexible composite films with exciting EMI shielding and strain sensing properties were constructed using a facile vacuum-assisted filtration process and transfer method. The films consisted of ultrathin AgNW/MXene (Ti3C2Tx)/AgNW conductive networks (1 μm) attached to a flexible polydimethylsiloxane (PDMS) substrate. The obtained AgNW/MXene/PDMS composite film exhibited an exceptional EMI shielding effectiveness of 50.82 dB and good flexibility (retaining 93.67 and 90.18% of its original value after 1000 bending and stretching cycles, respectively), which are attributed to the enhanced multilayer internal reflection network created by the AgNWs and MXene as well as the synergistic effect of PDMS. Besides EMI shielding, the composite films also displayed remarkable strain sensing properties. They exhibited a wide linear range of tensile strain up to 68% with a gauge factor of 468. They also showed fast response, ultralow detection limit, and high mechanical stability. Interestingly, the composite films could also detect motion and voice recognition, demonstrating their potential as wearable sensors. This study highlights the effectiveness of multifunctional flexible AgNW/MXene/PDMS composite films in resisting electromagnetic radiation and monitoring human motion, thereby providing a promising solution for the development of flexible wearable electronic devices in complex electromagnetic environments.

Slippery Graphene-Bridging Liquid Metal Layered Heterostructure Nanocomposite for Stable High-Performance Electromagnetic Interference Shielding.

Gallium-based liquid metal (LM) with intriguing high electrical conductivity and room-temperature fluidity has attracted substantial attention for its potential application in flexible electromagnetic interference (EMI) shielding. However, the EMI shielding performance of the existing LM-based composites is unsatisfying due to the irreconcilable contradiction between high EMI shielding efficiency (SE) and low thickness. In addition, the research on environmentally stable EMI shielding material has become an urgent need due to the increasingly sophisticated application scenarios. Herein, we prepared a reduced graphene oxide (rGO) bridging LM layered heterostructure nanocomposite with the liquid-infused slippery surface (S-rGO/LM), which exhibits an ultrahigh X-band EMI SE of 80 dB at a mere internal thickness of 33 μm, and an extremely high value of 100 dB at an internal thickness of 67 μm. More significantly, protected by the ultrathin (2 μm) yet effective slippery surface, the S-rGO/LM film exhibits exceptional EMI shielding stability (EMI SE stays above 70 dB) after enduring various harsh conditions (harsh chemical environments, extreme operating temperatures, and severe mechanical wearing). Moreover, the S-rGO/LM film also demonstrates satisfying photothermal behavior and excellent Joule heating performance (surface temperature of 179 °C at 1.75 V, thermal response <10 s), which endows it with the capability of anti-icing/de-icing. This work proposes a way to construct an LM-based nanocomposite with reliable high-performance EMI shielding capability, which shows great potential for applications in wearable devices, defense, and aeronautics and astronautics.

Hierarchical structures of carbon nanotubes anchored on core-sheath microrads toward electromagnetic wave absorption and shielding with Joule heating and superhydrophobic capacities

Hierarchical structures with synergistic dielectric-magnetic compositions are highly desired for electromagnetic wave absorption and interference shielding applications. Fabricating lightweight and high-performance electromagnetic protection composites with additional functions are demanded to suppress severe electromagnetic radiation and interference pollution. Herein, a unique three-dimensional hierarchical structure consisting of 1D multi-walled carbon nanotubes anchored on 1D MXene@CF core-sheath microrods are rationally proposed via electrostatic self-assembly and hydrothermal strategy as well as subsequent thermal-catalysis treatment. The multi-walled carbon nanotubes encapsulated with magnetic CoNi nanoparticles are immobilized onto core-sheath microrods matrix, constructing effective 1D/1D electron migration bridges and the uniformly dispersed magnetic component to facilitate magnetic coupling effect. Consequently, profiting from the optimized impedance matching, enhanced conduction loss, dielectric polarization, and magnetic loss, the as-prepared sample shows an outstanding absorption capacity with reflection loss value of −56.8 dB and X-band full absorption. When used as electromagnetic shielding materials, the composites exhibit exceptional electromagnetic interference shielding properties. In addition, the upgraded mechanical strength, remarkable voltage-driven Joule heating and superhydrophobic properties endow the absorbers with multi-scenario adaptability and long life-time applications. This work provides well-designed hierarchical structures for high-performance electromagnetic absorbing and shielding with the great prospect of multifunctional applications.

Multifunctional NiCo@RGO/SWNTs foam with oriented pore structure for excellent electromagnetic interference shielding

Constructing multifunctional material toward advanced electromagnetic interference (EMI) shielding has become a development trend. Carbon-based foams with excellent EMI shielding performance and structural stability for various environments are being widely studied. Here, an oriented pore structure was assembled with a carbon-based conductive skeleton, consisting of single-walled carbon nanotubes (SWNTs) and two-dimensional reduced graphene oxide (RGO), for facilitating the electromagnetic wave (EMW) to be multilevelly reflected in the confined space. In addition, magnetic NiCo nanoparticles were introduced to further improve the shielding performance by enhancing the magnetic loss. The as-prepared NiCo@RGO/SWNTs foam (NiCo@RSF) exhibited an exceptional EMI shielding effectiveness (SE) of 105 dB at the whole X band (8.2–12.4 GHz) with an ultralow density (0.0135 g cm−3). Moreover, the foam possessed extraordinary heat insulation and flame-retardant properties. Overall, the lightweight multifunctional foam with an oriented pore structure is thus promising for applications in advanced EMI shielding and other specific areas.

Janus-inspired flexible cellulose nanofiber-assisted MXene/Silver nanowire papers with fascinating mechanical properties for efficient electromagnetic interference shielding

MXene-based nanocomposites are highly desirable for electromagnetic interference (EMI) shielding applications. However, it is crucial but challenging to obtain an excellent trade-off between mechanical properties and EMI performances. Herein, inspired by Janus structure, flexible cellulose nanofiber-assisted MXene/silver nanowires (CNF-MXene/AgNWs) papers (CMAPs) are developed by a scalable sequential self-assembly plus a hot-pressing strategy. The ingenious introduction of highly conductive AgNWs into MXene forms a complementary leaf-like nanostructure, synergistically constructing highly effective conductive frameworks. Contributed by the designed Janus architecture, high-performance CNF substrate, and extensive hydrogen-bonding interactions, the resultant Janus CMAPs (J-CMAPs) with a low MXene/AgNWs addition of 30 wt% possess a high electrical conductivity (1066.85 S/cm), excellent mechanical strength (224.04 MPa) and modulus (9.98 GPa), exceptional EMI shielding effectiveness of 43.65 dB, and record-high EMI SE/t of 16788.51 dB cm−1 and SSE/t of 10543.18 dB cm2 g−1 with a reflection-dominant shielding mechanism, successfully achieving an outstanding balance between mechanical properties and EMI shielding performances. More importantly, high frequency structure simulator (HFSS) simulation in the frequency domain is further conducted to intuitively comprehend the attenuation process of electromagnetic waves and shield mechanism, verifying fascinating EMI shielding performances. Besides, the Janus paper also presents desirable Joule heating performances at low input voltage, short response time (<10 s), and superb heating stability and long-term steady reliability. We believe that the J-CMAPs demonstrate the great potential and advantage for advanced EMI shielding and portable thermal management applications.

Super-Stretchable and Self-Healing hydrogel with a Three-Dimensional silver nanowires network structure for wearable sensor and electromagnetic interference shielding

With the rapid development of the electronics industry, smart wearable electronics and electromagnetic interference (EMI) shielding materials have attracted tremendous interest. However, it is still a great challenge to maintain stable performance after damage. Herein, we prepare a super-stretchable and self-healing hydrogel composite with exceptional EMI shielding performance by the in situ polymerization of the acrylamide (AAm) and N-acryloyl-11-aminoundecanoic acid (A-11) in the silver nanowires (AgNWs) aerogel with a cellular structure. Benefiting the continuous three-dimensional AgNWs network, the hydrogel composite has high electrical conductivity (83 S/cm), outstanding resistance-strain response of more than 800% tensile strain, and exceptional EMI effectiveness (SE) of 66 dB in X-band, capable of monitoring human motions as a wearable sensor. Moreover, the reversible hydrophobic association and hydrogen bonding interactions endow the hydrogel composite with excellent self-healing capability (EMI SE healing efficiency of 90%). The healed hydrogel composite can still serve as a sensor to respond rapidly and steadily to human motions. The super-stretchable and self-healing hydrogel composite holds great promise for smart wearable electronics and EMI shielding.

Electromagnetic Interference Shielding by Reduced Graphene Oxide Foils

The pursuit of materials to avoid problems associated with electromagnetic pollution has become a relevant research topic. Here, we report the exceptional electromagnetic interference (EMI) shielding performance of freestanding reduced graphene oxide (rGO) foil produced by thermal reduction of graphene oxide (GO). The rGO foil with a thickness of 93.1 ± 12.4 μm reaches an efficient EMI shielding effectiveness (SE) value of 61.6 dB at 12.4 GHz. The excellent performance of the rGO foil is attributed to the thermal reduction of the GO foil, which restores the electrically conductive network, resulting in the electrical conductivity of 1.17 × 104 S m–1. To obtain a more complete profile of the EMI shielding performance of the rGO foil, measurements are performed in G- and C-bands, thus becoming the first study on the EMI shielding performance of an rGO film on a broad frequency range beyond the so-called X-band. The material sustains an EMI shielding efficiency higher than 99.999% over the frequency bands investigated, greatly desired in a wide range of commercial applications in this field.

Cryogenic-environment resistant, highly elastic hybrid carbon foams for pressure sensing and electromagnetic interference shielding

Elastic carbon foams are promising material candidates for various applications, including strain/pressure sensing and electromagnetic interference (EMI) shielding, but typically suffer from brittleness, low sensitivity, narrow pressure detection range, and poor performance stability. Herein, a facile and scalable method was demonstrated to fabricate carbon nanotube (CNT) embedded carbonized melamine foams (CNT/CMFs) by a direct pyrolysis process. The hybrid CNT/CMFs show tunable electrical conductivity while providing ultrahigh elasticity even under deep cryogenic conditions (−196 °C). An ultrahigh sensitivity (up to 103.24 kPa−1) and a broad pressure detection range (0–175 kPa) were achieved by the hybrid foam sensors, attributing to the hierarchical structures composed of a nanofibrous CNT layer and macropores. The foam-based sensors exhibit ultrahigh cryogenic-temperature resistance, which retains stable performance after immersing in liquid nitrogen for 36 h and experiencing 5000 cycles of repeated compression-release. Moreover, the CNT/CMFs show an exceptional EMI shielding effectiveness and a high specific shielding effectiveness of 6147.3 dB cm2 g−1 with an absorption-dominant shielding mechanism due to the highly porous structure. The cryogenic-temperature resistant CNT/CMFs with these superior strain/pressure sensing and EMI shielding performance are promising for their practical applications as wearable electronics operating in both mild and harsh environments.

Enhanced electromagnetic interference shielding performance of geopolymer nanocomposites by incorporating carbon nanotubes with controllable silica shell

The development of construction materials with exceptional electromagnetic interference (EMI) shielding performance is urgently needed to restrict the admittance of electromagnetic (EM) radiation. In this work, silica (SiO2)-coated carbon nanotubes (S-CNT) with different shell thicknesses (∼7, ∼10, and ∼15 nm) were prepared by a sol-gel method. The effect of SiO2 shell thickness on the EMI shielding performance of the resulting geopolymer nanocomposites was studied. The coated SiO2 shell effectively facilitated the dispersion of CNT in the geopolymer matrix due to the chemical reaction between SiO2 and the geopolymer. The dispersability of modified CNT could be further improved by increasing the thickness of the SiO2 shell. However, electron delocalization was hindered by the insulating SiO2 shell. The conductive nature of CNT was restored during geopolymerization when the SiO2 shell was thin. A high EMI shielding effectiveness (SE) of 24.2 dB was achieved for the geopolymer nanocomposite containing 5 vol% S-CNT with a thin SiO2 shell. The value achieved was more competitive than reported composites for construction when the sample thickness and filler content were considered.