Electromagnetic Interference Shielding Effectiveness Research Articles

Experimental Investigation on Electrical Conductivity, Dielectric Properties, and EMI Shielding Effectiveness of NiP/Graphene-Coated Natural Fiber

Experimental Investigation on Electrical Conductivity, Dielectric Properties, and EMI Shielding Effectiveness of NiP/Graphene-Coated Natural Fiber

Construction of polydopamine functionalized porous carbon network structure in polymer composites for excellent mechanical and electromagnetic interference shielding properties

Structural and functional integrated lightweight polymer-based composites with excellent mechanical and electromagnetic interference (EMI) shielding properties are urgently demanded in the field of advanced aerospace field. Effective design to construct the interfacial porous microstructures is crucial yet remains highly challenging for maximum EMI shielding effectiveness (SE) while improving the strength of composites. Herein, novel interfacial continuous network structures are constructed based on the in-suit synthesis of porous carbon network on the carbon fibers and chemical functionalized with polydopamine (PDA) to achieve simultaneous improvement of mechanical properties and EMI SE. Results indicate that the construction of active porous carbon networks significantly improves the surface activity and wettability of carbon fibers, which is conducive to enhancing the interfacial strength of the composites. Owing to the synergistic effect of physical enhancement for porous carbon and chemical reinforcement for PDA, the bending strength of the modified composite reaches 138.9 MPa, and the wear rate decreases by 82.9 %, demonstrating excellent mechanical properties. It is worth noting that the EMI SE reaches more than 62 dB in the X-band when the thickness of the modified composite is only 0.4 mm, showing excellent EMI shielding performance. Most importantly, this study provides solid basic knowledge of the interfacial structure design of composites, which is favorable for obtaining expected mechanical and EMI shielding performances and offers strong potential for applications in structural components of the aerospace and electronic equipment field.

Incorporating Loss Factor Modular Design for Full Ku-Band Microwave Attenuation in Double-Layered Graphene Aerogels.

The fabrication of absorption-dominant electromagnetic interference (EMI) shielding materials is a pressing priority to prevent secondary electromagnetic pollution in miniaturized electronic devices and communication systems. Meeting this goal has remained a tough challenge to keep pace with the rapid evolution of electronics due to the complex compositional and structural design and narrow operating bands. This work articulates a sound and simple strategy to precisely modulate the electrical conductivity of reduced graphene oxide (rGO), as the building block in lightweight double-layered rGO-film/rGO-aerogel/polyvinyl-alcohol (PVA) composites, for efficient microwave absorption over the entire Ku-band frequency range. These constructs reasonably comprised a porous absorption structure built from parallel rGO sheets aligned and prepared via freeze casting followed by freeze drying. The electrical conductivity and impedance of this layer were tuned by varying the annealing temperature from 400 to 800 °C, thereby adjusting the degree of reduction and the absorption characteristic. This layer was backed by a highly conductive rGO film reduced at a high temperature of 1000 °C, with a reflectivity of 97.5%. The incorporation of this film ensured high EMI shielding effectiveness of the double-layered structure through the absorption-reflection-reabsorption mechanism, consistent with the predicted values based on calculated loss factors and the input impedance of the structure. Accordingly, at an average EMI shielding effectiveness of 57.59 dB, the reflection shielding effectiveness (SER) and reflectivity (R) of the assembled composites were optimized to be as low as 0.22 dB and 0.049, respectively. This equates to approximately 99.999% shielding (SET) and ∼95% absorptivity (A) of the incident wave. This study opens new avenues for the development of lightweight (with a density as low as 15 mg/cm3) absorption-dominant EMI shielding composite materials with promising EMI shielding efficiency and potential applications in modern electronics.

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.

Synthesis of ionic liquid modified 1‐D nanomaterial and its strategical distribution into the biodegradable binary polymer matrix to get reduced electrical percolation threshold and electromagnetic interference shielding effectiveness

AbstractIonic liquid is increasingly being used as a chemical modulator of multi‐walled carbon nanotubes (MWCNT). Here, we report the practical method for producing biodegradable electromagnetic interference (EMI) shield films made of thermoplastic polyurethane (TPU), polybutylene adipate‐co‐terephthalate (PBAT), and 1‐(2‐aminoethyl)‐3‐methyl‐1H‐imidazol‐3‐ium modified MWCNT (MIL). The field emission scanning electron microscopy study of cryo‐fractured 50:50 PBAT/TPU blend giving co‐continuous morphology and subsequent polymer EMI shield nanocomposite material had shown the co‐continuous nanofiller distribution. The nanoparticles were chosen to be distributed in the PBAT portion, according to subsequent research employing HRTEM and DMA. The electrical percolation threshold (EPT) is determined to be situated within 1–3 wt% of nanoparticles loading as the remarkable shift in total EMI shielding efficiency from −14.6 dB (for 1 wt%) to −28.6 dB (for 3 wt%) of nanoparticle‐loaded film at 10 GHz (in X‐band region) for a 0.8 mm thick film reveals that the EPT is approximately at 2 wt% of nanoparticle loading. The effective EMI shielding of −37.3 dB was achieved by 10 wt% of MIL loading.

Rare earth ion-infused α-MnO2 nano-rods for excellent EMI shielding efficiency: Experimental and theoretical insights

In this communication, for the first time rare earth elements like Gd3+ and Er3+ ions are impregnated into the α-MnO2tunneled structure involving the modified chemical synthesis route followed by hydrothermal technique. X-ray diffraction patterns and Raman spectroscopy confirm the proper phase formation without any impurity. A theoretical in-depth DFT study for the electronic bands and variation of density of states with the infusion of rare earth elements into the host structure confirms the experimental findings and depicts the suitability of the material for the EMI shielding application. The novel synthesis technique helps to achieve uniform nanorod formation with a high specific surface area. Doping-induced defects, high surface-to-volume ratio, Maxwell-Wagner–Siller interfacial polarization, etc. lead to achieving high dielectric response with moderate tangent loss at a frequency range of 40 Hz to 1 MHz. Temperature-dependent dielectric behavior indicates the paramagnetic to ferromagnetic transition at 120 °C and 70 °C for the Gd- and Er-doped α-MnO2 samples respectively. The electromagnetic interference (EMI) shielding effectiveness (SE) has achieved a maximum of −43 dB at 15.3 GHz and − 46 dB at 15.3 GHz for Gd- and Er-doped α-MnO2 thin layer of thickness ∼600 μm respectively. Higher dipolar polarization, loss tangent, conductive pathways, and defects inside the crystal lead to attaining a high EMI shielding efficiency. This result reveals >99.997% EMI SE against the hazardous electromagnetic waves in the microwave/GHz frequency region.

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.

Ti3C2Tx MXene/delignified wood supported flame-retardant phase-change composites with superior solar-thermal conversion efficiency and highly electromagnetic interference shielding for efficient thermal management

The development of form-stable phase-change material (PCM) with solar-thermal harvest, electromagnetic interference (EMI) shielding, and flame-retardancy is crucial for efficient building energy management and conservation. Herein, novel Ti3C2Tx MXene/delignified wood supported form-stable phase-change composites (PMPCMs) with superior solar-thermal conversion efficiency, highly EMI shielding effects, and excellent flame-retardancy were fabricated by alkaline boiling delignification, ammonium dihydrogen phosphate (ADP) and MXene deposition, and melted n-octadecane impregnation. Benefiting from the powerful surface tension and capillary force of the wood-based support materials, PMPCMs can effectively encapsulate the melted n-alkane molecules and inhibit their leakage. The differential scanning calorimetry results showed that PMPCMs possessed superior n-octadecane encapsulation yield and high thermal energy storage density (166.9–191.6 J/g). Decorating delignified wood by MXene significantly improved the solar-thermal storage efficiency (up to 88.4 %) and EMI shielding performance of PMPCMs. The average EMI shielding effectiveness of PMPCM-10 was enhanced to 34.12 dB in X-band frequency range of 8.2–12.4 GHz. Moreover, with the introduction of the flame-retardant ADP, the peak heat release rate (pHRR) and total heat release (THR) of PMPCMs decreased noticeably, demonstrating the enhanced flame retardancy of delignified wood supported phase-change composites. In summary, PMPCMs exhibited superior application prospects in building energy management and electromagnetic shielding fields.

Anisotropic high-strength polyimide-based electromagnetic interference shielding foam based on cation-π interaction

Effective electromagnetic interference (EMI) shielding plays a vital role in numerous applications by mitigating the detrimental impacts of electromagnetic waves. In this study, we developed a novel anisotropic MXene@PI hybrid foam for efficient EMI shielding using a synergistic approach involving directional freezing, freeze-drying, thermal imidization, and a subsequent dip-coating step. The cation-π interaction was harnessed to create a crosslinked structure for enhancing the mechanical properties of the polyimide (PI) foam and also to improve the interfacial interaction between MXene and the inner wall of the foam. The foam exhibited a tubular structure in a vertical frozen direction while adopting a honeycomb-like structure in a parallel freezing direction. The anisotropic MXene@PI-5 hybrid foam demonstrated remarkable EMI shielding effectiveness of up to 62.7 dB in the vertical freezing direction, 158.02 % higher than that observed in the parallel direction, and 109.70 % higher than that in the isotropic foam with the same loading of MXene. This anisotropic MXene@PI hybrid foam offers great potential for applications requiring efficient EMI shielding, such as aerospace, electronics, telecommunications, etc. The unique combination of the cation-π interaction and anisotropic structure provides enhanced EMI shielding properties, making it a promising candidate for future EMI shielding materials.

Construction of strong and superhydrophobic MXene composite films by binary organosilane cross-linking for electromagnetic interference shielding and joule heating

Transition-metal carbide and/or nitride (MXene) with outstanding electrical conductivity and surface chemistry tunability shows great potential for constructing high-performance electromagnetic interference (EMI) shielding materials. Unfortunately, MXene has poor mechanical properties and ambient stability, limiting its practical applications. In this work, strong and superhydrophobic MXene/carboxymethylcellulose sodium (S-MC) composite films were prepared by blade coating followed by binary organosilane modification. Through the joint contributions of hydrogen-bonding interaction, alignment, and organosilane cross-linking of MXene nanosheets, the proposed S-MC films achieved outstanding mechanical properties and EMI shielding performance. For instance, the S-MC composite film containing 90 wt% MXene content demonstrated high specific EMI shielding effectiveness (152 069 dB/cm) and strong tensile strength (181.5 MPa), surpassing those of other reported MXene-based shields. The S-MC films also had excellent Joule heating performance with low applied voltage and quick thermal response. Furthermore, the binary organosilane cross-linking endowed the S-MC films with superhydrophobic properties by inducing rough surface and low surface energy, resulting in stable conductivity and EMI shielding performance in oxidizing and aqueous environments. The developed S-MC films showed enormous potential applications for EMI shielding and Joule heating. Our study offers a novel and scalable strategy to construct strong, stable, and multifunctional MXene-based composites.

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.

Facile synthesis and characterization of polymer composites with cobalt ferrite and biomass based activated carbon for microwave absorption

In this work, flexible EMI shield materials have been prepared by the solution cast technique using AC-STG {activated carbon derived from Sal tree's gum}, CoFe2O4 nanoparticles and a polymer electrolyte {P(VDF-TrFE) + 15 wt% LiTFSI + 50 wt% EMIMTFSI}. The prepared polymer composites have been characterized for structural, morphological, thermal, ionic conductivity, dielectric, and magnetic properties. EMI shielding effectiveness has been obtained in the X-band (8.2–12.4 GHz). AC-STG particles have been characterized using XRD, FESEM EDX with elemental mapping, FTIR and RAMAN techniques. The CoFe2O4 (CF) nanoparticles have been prepared using the hydrothermal method. The highest ionic conductivity of ∼ 3.24х10−3 S.cm−1 for polymer electrolyte (PE15IL50) has been obtained at room temperature. On addition of AC-STG and CF particles to the polymer electrolyte, enhanced EMI shielding effectiveness and thermal stability of the composite films has been achieved. Also, FTIR results give the confirmation of interaction between the polymer electrolyte, AC-STG and CF particles. This study demonstrates that the EMI shielding properties of the polymer composite (PE15IL50AC-STG4CF5) get improved owing to the synergy between the properties of AC-STG and CF nanoparticles resulting in EMI shielding of ∼ 49.6 dB at 8.2 GHz (absorption ∼ 99.99%). There are three factors, viz., dielectric losses, magnetic losses and interfacial polarization which contribute majorly to this much desirable EMI performance. The studies being reported indicate PE15IL50AC-STG4CF5 polymer composite to be an excellent biomass-based composite for EM wave absorption.

Construction of alternating multilayer films with stable absorption-dominated electromagnetic shielding performance and reinforced mechanical properties via interface engineering

As an ideal material to lessen electromagnetic pollution, absorption-dominated electromagnetic interference (EMI) shielding composites still face the problems of complicated structure design and insufficient performance stability. Herein, an alternating multilayer film with stable absorption-dominated EMI shielding effectiveness (SE) and reinforced mechanical properties is fabricated by constructing hydrogen bonding between multilayers interface. When the layers increase to 4, benefiting from the construction of multilayer structure and the stronger interaction, the reflective shielding effectiveness decrease to 2.9 dB, the absorption coefficient of multilayer film increases from 0.13 to 0.52, the retention rate of EMI SE increases from 1.0 % to 97.6 % after bending 1000 cycles, and the tensile strength is enhanced from 5.7 MPa to 27.3 MPa. The calculated binding energies and the experimental results show that the interaction between Pluronic F127 anchored on the porous film and cellulose nanofibers entangled on the carbon nanotubes layer increases the interlayer interaction force and durability of EMI SE.

An ultra-thin and highly efficient electromagnetic interference shielding composite paper with hydrophobic and antibacterial properties

Facing the increasing electromagnetic interference (EMI) pollution in the living environment, it is a new trend to explore an efficient EMI shielding material with facile fabrication and a wide range of application scenarios. A hydrophobic composite paper composed of silver nanowires (AgNWs) and kapok microfibers cellulose (MFC) was modified by methyl trimethoxy silane (MTMS) through a simple method. As a result, the composite paper has a good EMI shielding effectiveness (EMI SE) of 61.7 dB with electrical conductivity of 695.41 S/cm. The modification of MTMS improved the thermal stability performance of composite paper, which also increased its water contact angle to 113°. The free silver ions (Ag+) released from AgNWs can kill surrounding microbial bacteria, endowing the composite paper with good antibacterial property. Water resistance and antibacterial property enable MTMS/AgNWs/MFC composite paper to cope with complex application environments.

MOF@wood Derived Ultrathin Carbon Composite Film for Electromagnetic Interference Shielding with Effective Absorption and Electrothermal Management

AbstractRecently, there has been a growing demand for ultra‐thin carbonized wood films (CWF) with high shielding efficiency (SE) to replace non‐renewable alternatives. Researchers aim to enhance electromagnetic (EM) wave absorption and improve electromagnetic interference (EMI) SE in CWF materials to reduce secondary pollution from reflected EM waves. In this work, the carbonized wood composite film (CWF/EP/Co) with a thickness of 120 µm through the process of hot‐pressing and carbonizing wood soaked in a mixed solution of water‐borne epoxy (EP) and Co/Zn‐MOF (ZIF‐67/8) is obtained. The CWF/EP/Co film exhibits excellent conductivity (105 S cm−1) and demonstrates an excellent EMI SE (73 dB) at a 200 µm thickness. Remarkably, the specific EMI shielding effectiveness (SSE/t) of CWF/EP/Co films reached 15833.3 dB·cm2·g−1 in the X‐band, making it the highest reported value among all wood‐derived EMI shielding materials. CWF/EP/Co films have a high absorption coefficient (A) of 0.4, indicating their effectiveness in absorbing EM waves. Furthermore, the EMI shielding effect of the large‐scale wallpaper (170 mm×170 mm) is confirmed by finite element analysis. Additionally, the CWF/EP/Co film exhibits good mechanical properties and effective Joule heating performance. This shielding film shows promise in applications such as buildings and smart homes, providing EMI shielding and warming effects.

Heterogeneous Ti3C2Tx MXene-MWCNT@MoS2 Film for Enhanced Long-Term Electromagnetic Interference Shielding in the Moisture Environment.

MXene, as a novel two-dimensional (2D) material, has unique inherent features such as lightweight, flexibility, high electrical conductivity, customizable surface chemistry, and facile solution processability. However, utilizing MXene (Ti3C2Tx) films for long-term electromagnetic interference (EMI) shielding poses challenges, as they are susceptible to chemical deterioration through oxidation into TiO2. In this work, an ultrathin heterogeneous film of Ti3C2Tx MXene integrated with multiwalled carbon nanotubes supporting MoS2 clusters (MXene/MWCNT@MoS2) was developed. The heterogeneous film with 15 wt % of MWCNT@MoS2 clusters exhibited improved EMI shielding performance such as the highest EMI shielding effectiveness of 50 dB and the specific shielding effectiveness of 20,355 dB cm2 g -1, mainly attributed to the excellent electrical conductivity, distinctive porous structure, and multiple interfacial interactions. The heterogeneous films underwent extended exposure to a moisture environment (35 days), and their structural stability and EMI shielding performance were enhanced by the integration of MWCNT@MoS2 clusters. As a result, the engineered heterostructure of multilayered hybrid films holds promise as a viable option for improving the EMI shielding effectiveness and stability of Ti3C2Tx MXene.

Ultrathin carbon layer coated MXene/PBO nanofiber films for excellent electromagnetic interference shielding and thermal stability

In this study, a carbon layer coated MXene/poly(p-phenylene-2,6-benzobisoxazole) nanofibers (PNFs) (MXene/PNF@C) EMI shielding composite film was obtained through polymer infiltration and pyrolysis (PIP) technique. The introduction of the carbon layer improved both the electrical and thermal conductive pathways of the film leading to the enhancement of its electrical conductivity(σ), thermal conductivity coefficient (λ) and EMI shielding effectiveness (SE). Meanwhile, thermal annealing reduced the defects of PBO molecular chains and improved the mechanical properties of the composite film. When the content of MXene is 50 wt% and the thickness of the film is only 37 μm, MP50@C-400 composite film has the best comprehensive properties, with the σ, λ, specific EMI SE (SEt) and tensile strength is 1760 S/m, 5.64 W/(m·K), 1108.1 dB/mm and 66.8 MPa, respectively, and its weight loss is only 24.1% at 800°C. The composite film provides important application prospects in 5G communication technology, wearable equipment and artificial intelligence.

Stretchable textile with ultra-high electromagnetic interference shielding performance based on porous wrinkled conductive network

The soaring growth of flexible electronic devices has boosted the demand for electromagnetic interference (EMI) shielding materials with excellent stretchability, stability and even breathability. However, it is still a challenge to develop conductive materials with outstanding stretchable EMI shielding performance. In this work, we developed a textile with porous wrinkled conductive network through in situ polydopamine-assisted deposition of silver nanoparticles (AgNPs) on wrinkled fiber mat and polydimethylsiloxane post modification. This unique wrinkled conductive networks endows the textile with excellent electrical conductivity (103700 S/m), good breathability, superhydrophobicity, and ultra-high stretchable EMI shielding properties. The EMI shielding effectiveness (EMI SE) of the textile reaches 101.1 dB in unstretched state and still maintains at 94.1 dB at 100 % tensile strain. The superhigh EMI SE under such a high strain is much higher than the previously reported results so far. Moreover, the textile shows exceptionally good cyclic tensile durability under 100 % stain. After 1000 tensile cycles with 100 % strain, the EMI SE of sample only drops by 3.8 %. This work provides a new path for developing stretchable high EMI shielding performance materials, which is of great significance to solve the EMI problems of emerging flexible and wearable electronic devices.

Effect of Platinum Oxide in Enhancing EMI Shielding Effectiveness of Silver Doped Polyaniline-Platinum Oxide Composites

In this study, we used green tea extract to prepare Silver-PANI nanocomposites and incorporated varying percentages of platinum oxide through in-situ chemical polymerization. The synthesized Ag-PANI/PtO2 conducting polymer nanocomposites were characterized using FT-IR, XRD, and SEM analysis, which showed uniform incorporation of PtO2 in the nanocomposites. EMI shielding effectiveness results demonstrated that the Ag-PANI/PtO2 (10%) composite effectively shields electromagnetic interference. The EMI SE results showed that PtO2 exhibited good absorption in the range of 2-3 GHz, indicating its conducting behaviour. Additionally, the Ag-PANI/PtO2 (6%) and Ag-PANI/PtO2 (10%) composites demonstrated good absorption in this range, likely due to the proper mixing of platinum oxide and silver-decorated polyaniline within the polymer matrix. Therefore, silver polyaniline decorated conducting polymer composites are a promising material for effectively shielding electromagnetic radiation in electronic devices.

High-Efficiency Electromagnetic Interference Shielding from Highly Aligned MXene Porous Composites via Controlled Directional Freezing.

Lightweight porous composite materials (PCMs) with outstanding electromagnetic interference (EMI) shielding performances are ideal for aerospace, artificial intelligence, military, and other fields. Herein, a three-dimensional Ti3C2Tx MXene/sodium alginate (SA)/carbon nanotubes (CNTs) (MSC) PCMs was prepared by a controlled directional freezing process. This method constructs a directionally ordered porous structure, which can make the incident electromagnetic waves reflect and scattered several times in the PCMs. The introduction of CNTs into the MSC PCMs can form three-dimensional conductive networks with MXene, thus improving the conductivity and further improving the electromagnetic shielding performance. Furthermore, the SA with abundant hydrogen bonding can strengthen the interlayer interaction between MXene and CNTs. Profiting from the controlled directional freezing and highly aligned porous structure, the MSC PCMs with 75 wt % CNTs exhibit ultrahigh conductivity of 1630 S m-1, an ultrahigh EMI shielding effectiveness of 48.0 dB in X-band for electromagnetic waves incident perpendicular to the hole growth direction, and compressive strength of 72.3 kPa. The as-prepared MSC PCMs show excellent EMI shielding and mechanical properties and have significant applications in the preparation of an entirely novel type of EMI shielding materials with an absorption-based mechanism.