High-efficiency Electromagnetic Interference Shielding Research Articles

Asymmetric multilayered MXene-AgNWs/cellulose nanofiber composite films with antibacterial properties for high-efficiency electromagnetic interference shielding

• Multilayer films containing cellulose nanofiber (CNF) layers, CNF/MXene layers, and CNF/silver nanowires (CNF/AgNWs) layers were fabricated by an efficient and easy-to-use vacuum filtration method. • The effects of different conductive layers order and different number of layers on electromagnetic shielding performance were investigated. • Due to the excellent layered structure, the MXene-AgNWs/cellulose nanofiber composite film exhibits excellent EMI shielding capability at an ultra-thin thickness. • Benefiting from the properties of silver nanowires, the multifunctional shielding composite exhibits excellent antibacterial properties and better environmental adaptability. Flexible, lightweight, robust and versatile properties are essential for the next generation of wearable as well as intelligent electromagnetic interference (EMI) shielding materials. In this work, multilayered films containing cellulose nanofiber (CNF) layers, CNF/MXene layers, and CNF/silver nanowires (CNF/AgNWs) layers were fabricated by an efficient and easy-to-use vacuum filtration method. Compared with a uniformly mixed film, the resultant layered composite films that loaded with a low MXene and AgNWs content exhibit superior mechanical properties with a tensile strength of 137 MPa, a strain at break of 5.7%, excellent EMI shielding effectiveness (EMI SE) of 61.9 dB, and higher EMI SE/t of 20,653 dB cm −1 . This is attributed to the high-performance CNF substrate, the highly efficient layered structures, and extensive hydrogen-bonding interactions. In particular, a high degree of ohmic loss of multiple interfaces and polarization relaxation of local defects, as well as an abundance of terminal groups, favor the loss of electromagnetic waves (EMW) within the material. In addition, the prepared multifunctional layered composite films also show good antibacterial properties. As a result, the obtained new kind of flexible layered structure EMI shielding composite films with excellent EMI shielding performance, and mechanical properties present promising application prospects in the fields of EMI shielding and protection for aerospace, portable, and wearable flexible electronic devices.

Silver Nanowires Coated Nitrocellulose Paper for High-Efficiency Electromagnetic Interference Shielding.

A thin and conductive coating on an environmentally friendly polymer is imperative for protecting sensitive electronic devices. In this regard, a series of silver nanowires (AgNWs) coated nitrocellulose (NC) papers are fabricated by a simple and fast processed vacuum-assisted filtration method by varying filtrate volume to address electromagnetic interference. Their structural and EMI shielding performance is analyzed. The submicron thick and the lighter paper reveal the conductive AgNWs interwoven on the rough NC surface, making a 2D in-planar structure. Due to a strongly interconnected network, the coated paper displays an exceptional electrical conductivity of 8603 S/m. Despite having a minimum AgNW coating thickness of ∼0.69 μm and an area density of 0.041 mg/cm2, an ultrahigh EMI shielding effectiveness (SE) of about 69.4 dB (a specific EMI SE (SE/t) of 1005797 dB/cm) in the entire X-band (8-12 GHz) region is achieved. The effective material parameters, extracted using plane-wave theory, indicate that AgNWs form closed current loops resulting in magnetic losses. These AgNWs coated NC papers synthesized by a simple procedure are promising EMI shielding materials for current emerging electronic devices.

Superhydrophobic Ag/Viscose Non-woven Fabrics with Excellent Electric Heating and High-efficient Electromagnetic Interference Shielding

Superhydrophobic Ag/Viscose Non-woven Fabrics with Excellent Electric Heating and High-efficient Electromagnetic Interference Shielding

Sandwich-like high-efficient EMI shielding materials based on 3D conductive network and porous microfiber skeleton

High-efficient and durable electromagnetic interference (EMI) shielding materials are urgently needed to address electromagnetic wave pollution. In this study, Ti3C2TX MXene and silver nanowires (AgNWs) were integrated at a porous microfiber skeleton (PMS) via a dip-coating method to form a sandwich-like conductive network, followed by a polyurethane (PU) fixation. Firstly, PMS was dipped with AgNWs dispersion (1D AgNWs acts as the interlayer) and then immersed in Ti3C2TX MXene nanosheets suspension (2D Ti3C2TX MXene acts as the upper and lower layers). Finally, an EMI shielding material with a sandwich-like conductive network was constructed by immersing it in diluted PU solution at ambient temperature for fixation. The conductivity of the resultant shielding material is found to be 1896.7 s⸱m-1, correspondingly, the average EMI shielding effectiveness (SE) is as high as 100.1 dB. The ideal conductivity of AgNWs and Ti3C2TX MXene, combined with the porous structure of microfiber substrate are believed to impart the resultant material excellent EMI shielding characteristics. In addition, benefiting from the protective effect of the outermost PU thin layer, the coated materials still remain their high shielding performance even after ultrasonic washing for 30 min (100 W), strong acid (pH 2.0), strong base (pH 12.0), 2000 bending-releasing cycles, 2000 folding-releasing cycles, and 1000 twisting-releasing cycles, showing excellent EMI shielding durability.

Multifunctional CoFe2O4@MXene-AgNWs/Cellulose Nanofiber Composite Films with Asymmetric Layered Architecture for High-Efficiency Electromagnetic Interference Shielding and Remarkable Thermal Management Capability.

Developing high-efficiency electromagnetic interference (EMI) shielding composite films with outstanding flexibility and excellent thermal management capability is vital but challenging for modern integrated electronic devices. Herein, a facile two-step vacuum filtration method was used to fabricate ultrathin, flexible, and multifunctional cellulose nanofiber (CNF)-based composite films with an asymmetric layered architecture. The asymmetric layered structure is composed of a low-conductivity CoFe2O4@MXene/CNF layer and a highly conductive silver nanowires (AgNWs)/CNF layer. Benefiting from the rational placement of the impedance matching layer and shielding layer, as well as the synergistic effect of electric and magnetic losses, the resultant composite film exhibits an extremely high EMI shielding effectiveness (SE) of 73.3 dB and an average EMI SE of 70.9 dB with low reflected efficiency of 4.9 dB at only 0.1 mm thickness. Sufficiently reliable EMI SE (over 95% reservation) is attained even after suffering from continuous physical deformations and long-term chemical attacks. Moreover, the prepared films exhibit extraordinary flexibility, strong mechanical properties, and satisfactory thermal management capability. This work offers a viable strategy for exploiting high performance EMI shielding films with attractive thermal management capacity, and the resultant films present extensive application potential in aerospace, artificial intelligence, advanced electronics, stealth technology, and the national defense industry, even under harsh environments.

Dopants versus defects: Intense confrontation of nitrogen-doped Ti3C2Tx for enhanced electromagnetic interference shielding

MXene has been extensively studied in electromagnetic interference (EMI) shielding. In this work, the defects-rich nitrogen-doped Ti3C2Tx (N-doped Ti3C2Tx) was fabricated for EMI shielding. An intense confrontation of dopants versus defects was observed: N dopants offering extra electrons improved electrical conductivity. And the defects-rich characteristics contributed to its reduction, which consisted of crumpled morphology, structural collapse, the introduced N heteroatoms, and pore nature. The end of this conflict revealed that heteroatoms N led to a significant improvement of conductivity and suppressed the negative impact of defects, resulting in the reflection-dominant EMI shielding feature. Owning to greater advantage of dopants, the N-doped Ti3C2Tx prepared at 550 °C/paraffin composite with the most defects exhibited the highest conductivity. And it achieved the maximum total EMI shielding effectiveness from 8.0 to 12.4 GHz (covering the entire X-band) of 62.15 dB. This work presents a new paradigm for MXene-based materials utilizing the structure-property relationship and manifests an enormous application promise for new high-efficiency EMI shielding materials in the future.

Methylene blue adsorption derived thermal insulating N, S-co-doped TiC/carbon hybrid aerogel for high-efficient absorption-dominant electromagnetic interference shielding

The development of absorption-dominant electromagnetic interference (EMI) shielding materials with high-efficiency EMI shielding effectiveness (SE) and low reflection (R) is crucial but challenging for next-generation electronics devices and telecommunication. In this regard, a facile and environmentally friendly approach was proposed to fabricate N, S-co-doped TiC/carbon hybrid aerogels with hierarchically porous architecture through MXene/cellulose hybrid hydrogels as precursors for adsorbing dyes, followed by freeze drying and carbonization process. Profiting from the synergistic effect of highly interconnected three-dimensional (3D) porous structure, heterogeneous conductive network with greatly conductive difference as well as heteroatoms-doping induced dipole polarization, the resultant aerogel with an ultra-low density (47.1 mg/cm3) achieves a highly efficient EMI SE of 84.3 dB at 12.4 GHz (average 81.8 dB in the X-band) and a superior absorption coefficient of 0.68 simultaneously. Meanwhile, the highly porous structure endows the prepared aerogels with outstanding thermal insulating capacity, which is essential to provide infrared stealth and radar stealth for military equipment and to protect sensitive electronic devices from high-temperature attacks. This work offers a prospective strategy for constructing high-performance absorption-dominated EMI shielding materials with excellent thermal insulation properties, and the obtained aerogels present broad application prospects in the fields of aviation, portable electronic equipment and national defense industry.

3D printed polylactic acid/graphene nanocomposites with tailored multifunctionality towards superior thermal management and high-efficient electromagnetic interference shielding

The relative lack of printable materials with tailored functionalities limits the development of three-dimensional (3D) printing techniques. Herein, a promising multifunctional filament was fabricated by incorporating graphene nanosheets (GNs) into polylactic matrix via a solution-blending method. With this strategy, the uniform-distributed GNs were obtained in the matrix, even with a high GNs concentration (9.08 vol%). The resultant nanocomposites exhibited desired functionalities, that the thermal conductivity (Tc) was up to 3.22 W/m·k, more than ten times that of pure one (0.25 W/m·k), and the electromagnetic interference shielding (EMI SE) reached 34.9 dB at X-band region, meaning 99.97 % shielding efficiency to EWMs energy. Thereafter, by tapping into the manufacturing potential of 3D printing, a series of ideal parts featuring arbitrarily designated structures and exceptional performance was constructed. Particularly, the 3D-printed heat sinks possessed outstanding behaviors in thermal management, where the corresponding initial dissipating rate achieved a 266 % improvement over that of the pure one. Besides, the 3D-printed shielding module posed high-efficiency EMI SE performance, corresponding to 35.8 dB at a specific Bluetooth-interaction signal (2.4 GHz). Overall, this innovative study not only enriches the printable materials with tailored multifunctionality but also brings the promising potential for applications in the next-generation functional parts.

Nonionic waterborne polyurethane/polypyrrole/silver nanowires coating film with high-efficient electromagnetic interference shielding

A flexible nonionic waterborne polyurethane/polypyrrole/silver nanowires (NWPU/PPy/AgNWs) coating film with high-efficient electromagnetic interference shielding effectiveness (EMI SE) was achieved by in-situ polymerization followed by mixing with AgNWs dispersion, via casting method. The SE of NWPU/PPy film without AgNWs is 15 dB with a thickness of 1.6 mm. When the loading of AgNWs is 40 wt%, the conductivity of resultant film with a thickness of 0.48 mm reaches 1026.1 s. m−1, and the SE increases to 64.2 dB. Furthermore, this flexible coating film shows excellent EMI shielding reliability to resist bending and ultrasonic water washing.

Ultrastrong and Hydrophobic Sandwich-Structured MXene-Based Composite Films for High-Efficiency Electromagnetic Interference Shielding.

Electromagnetic interference (EMI) shielding materials are highly necessary to solve the problem of electromagnetic radiation. Transition-metal carbide/nitride (MXene) materials offer great potential for the construction of high-performance EMI shields because of their high electrical conductivity and versatile surface chemistry. However, MXene generally suffers from poor mechanical and oxidation-resistant properties, which hinders its practical applications. Herein, flexible, strong, and hydrophobic sandwich-structured composite films (H-S-MXene), consisting of a conductive MXene layer and supporting aramid nanofiber layer, were fabricated using step-by-step vacuum-assisted filtration and dip coating. Given the unique sandwich structure, hydrogen bonding interactions, and covalent cross-linking of the MXene sheets, the H-S-MXene composite films demonstrated simultaneously excellent EMI shielding and mechanical properties. The EMI shielding effectiveness of the H-S-MXene composite film with 20 wt % MXene content reached 46.1 dB at thickness of 23.2 ± 0.5 μm, and the tensile strength of the film reached 302.1 MPa, which outperformed other reported EMI shielding materials. The excellent mechanical flexibility and hydrophobicity of the H-S-MXene composite films ensured a stable EMI shielding performance, which could withstand cycled bending, torsion, and exposure to aqueous environments. These impressive features made the H-S-MXene composite films promising candidates for electronic devices and aerospace. This study provides important guidance for the rational design of stable MXene-based composites with advanced properties.

A laminated carbon nanotubes/silicon boron carbonitride film for high-efficiency electromagnetic interference shielding with oxidation resistance

Constructing layer-structured carbon/ceramic composites is promising for achieving high-performance and high-temperature electromagnetic interference (EMI) shielding materials, in which the rational composition and structural manipulation is critical. Here, a laminated SiBCN@CNTs/SiBCN film with a unique hierarchical structure is prepared using multi-layered carbon nanotubes (CNTs) films as the skeleton by alternatively stacking SiBCN@CNTs layers and SiBCN layers, and its thickness varies from 0.13 to 1.10 mm depending on the number of stacked layers (i.e., 1 to 6 layers) and the concentration of polyborosilazane precursor for impregnation (i.e., 10–70 wt%). Enlarging the thickness of the SiBCN@CNTs layers from 60 to 130 μm in the film or increasing their stacking numbers could both enhance the shielding effectiveness due to the introduction of additional interfacial and interlayer multi-reflection to extend the propagation path of electromagnetic waves for effective wave interference. Consequently, a high EMI shielding effectiveness of 49.4 dB has been achieved on SiBCN@CNTs/SiBCN-50-3, corresponding to a high specific shielding effectiveness (SETotal/d) of 182.9 dB mm−1, higher than previous pure ceramic shielding materials and carbon/ceramic composites. Moreover, because of the effective protection of SiBCN for CNTs, the SETotal of the film is still up to 23.9 dB after oxidation at 1000 °C for 2 h. Therefore, the laminated SiBCN@CNTs/SiBCN film represents an ideal candidate for high-efficiency EMI shielding material used in oxidation environments.

Superhydrophobic Ti3C2Tx MXene/aramid nanofiber films for high-performance electromagnetic interference shielding in thermal environment

Nowadays, novel two-dimensional (2D) material MXene have attracted extensive interest in the electromagnetic interference (EMI) fields because of outstanding metallic conductivity, unique 2D structure. While it remains a great challenge to construct high-performance EMI shielding MXene-based materials with features of stability and durability and strong mechanical properties. And there are few reports on the evolution of EMI shielding performance of MXene at elevated temperature. Herein, hierarchical structure superhydrophobic Ti3C2Tx MXene/aramid nanofiber (SHMA) films were fabricated by strategy of layer-by-layer construction and their EMI shielding at elevated temperature were investigated. Benefiting from the hierarchical structure, different layers shoulder their independent desired functions, and then work together to ensure that SHMA has high-efficient EMI shielding performance with mechanical stability, moisture stability and thermal stability. Interestingly, the SHMA films exhibited excellent EMI shielding performance with EMI shielding effectiveness (SE) over 49.7 dB at thickness of 70 μm in temperature ranging from 25 to 300 °C. After heat test, the EMI SE of SHMA increased anomalously from 49.7 to 63.2 dB, and the variation of EMI shielding performance and microstructure of SHMA in thermal environment had been intensively investigated and discussed. Moreover, the EMI SE of SHMA was maintained after 6 months and 5 cycles of heating at 300 °C in air. These results indicate great application potential of SHMA as high-performance EMI shielding material in civil, military high-tech equipment and integrated electronics operating in thermal environment.

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.

High-Efficiency Electromagnetic Interference Shielding of rGO@FeNi/Epoxy Composites with Regular Honeycomb Structures

HighlightsThe rGH@FeNi/epoxy electromagnetic interference (EMI) shielding composites with regular 3D honeycomb structures were prepared by sacrificial template, freeze-drying and vacuum-assisted impregnation of epoxy resin.The construction of 3D honeycomb structure and electromagnetic synergistic effect significantly increase the EMI shielding effectiveness and reduce the secondary contamination.The rGH@FeNi/epoxy composites possess excellent thermal stability and mechanical properties.

3d Printed Polylactic Acid/Graphene Nanocomposites with Tailored Multifunctionality Towards Superior Thermal Management and High-Efficient Electromagnetic Interference Shielding

3d Printed Polylactic Acid/Graphene Nanocomposites with Tailored Multifunctionality Towards Superior Thermal Management and High-Efficient Electromagnetic Interference Shielding

3d-Printed Ultralight Mwcnt@Cnf Aerogel Scaffolds with Hierarchical Pores for High-Efficiency Electromagnetic Interference Shielding

3d-Printed Ultralight Mwcnt@Cnf Aerogel Scaffolds with Hierarchical Pores for High-Efficiency Electromagnetic Interference Shielding

Flexible and multifunctional phase change composites featuring high-efficiency electromagnetic interference shielding and thermal management for use in electronic devices

Achieving both efficient thermal management and electromagnetic interference (EMI) shielding for intelligent electronic devices is one of the major challenges currently faced by materials engineers. Most reported material innovations focus only on single purpose projects, and issues including complex preparation methods, poor mechanical strength, and low economic benefit are common. In this study, the shape-stable phase change composites (SSPCCs) of polypropylene/carbon nanotubes/ferroferric oxide/paraffin wax (PP/CNTs/Fe3O4/PW) were fabricated using a facile process with excellent thermal management performance, EMI shielding effectiveness (EMI SE), and appropriate flexibility. This advantageous manufacturing technology enables CNTs to form effective thermal and electrical pathways in the matrix. With the synergistic effect of CNTs and Fe3O4, the resulting SSPCC displays high volume conductivity (31.0 S/m), suitable thermal conductivity (0.59 W/mK), and excellent EMI SE (41.2 dB). Additionally, SSPCC retains effective thermal stability and durability, and excellent temperature-control property. The convenient manufacturing method has tremendous application prospects for advanced thermal management and EMI shielding of future integrated circuits, as well as excellent overall performance.

A Healable and Mechanically Enhanced Composite with Segregated Conductive Network Structure for High-Efficient Electromagnetic Interference Shielding

HighlightsThe cationic waterborne polyurethanes microspheres with Diels-Alder bonds were synthesized for the first time.The electrostatic attraction not only endows the composite with segregated structure to gain high electromagnetic-interference shielding effectiveness, but also greatly enhances mechanical properties.Efficient healing property was realized under heating environment.It is still challenging for conductive polymer composite-based electromagnetic interference (EMI) shielding materials to achieve long-term stability while maintaining high EMI shielding effectiveness (EMI SE), especially undergoing external mechanical stimuli, such as scratches or large deformations. Herein, an electrostatic assembly strategy is adopted to design a healable and segregated carbon nanotube (CNT)/graphene oxide (GO)/polyurethane (PU) composite with excellent and reliable EMI SE, even bearing complex mechanical condition. The negatively charged CNT/GO hybrid is facilely adsorbed on the surface of positively charged PU microsphere to motivate formation of segregated conductive networks in CNT/GO/PU composite, establishing a high EMI SE of 52.7 dB at only 10 wt% CNT/GO loading. The Diels–Alder bonds in PU microsphere endow the CNT/GO/PU composite suffering three cutting/healing cycles with EMI SE retention up to 90%. Additionally, the electrostatic attraction between CNT/GO hybrid and PU microsphere helps to strong interfacial bonding in the composite, resulting in high tensile strength of 43.1 MPa and elongation at break of 626%. The healing efficiency of elongation at break achieves 95% when the composite endured three cutting/healing cycles. This work demonstrates a novel strategy for developing segregated EMI shielding composite with healable features and excellent mechanical performance and shows great potential in the durable and high precision electrical instruments.

Random nano-structuring of PVA/MXene membranes for outstanding flammability resistance and electromagnetic interference shielding performances

Nowadays, highly flexible, ultrathin, and conductive polymer composites are exceptionally desirable for electromagnetic interference shielding (EMI) applications due to their unique mechanical strength and electrical and flame-resistant properties. While the traditional nanocomposites blending remains the mainstream method to fabricate polymer/inorganic composites, it results in poor electrical conductivity caused by the discontinuous connection of conductive network as well as the unsatisfactory mechanical strength limiting the further practical applications. Herein, we introduce a facile and practical methodology involving the fabrication of self-interlocked poly (vinyl alcohol) (PVA) and conductive Ti3C2Tx MXene networks, then combining them to construct a nanostructure-engineered PVA/MXene membrane. This membrane exhibits superior mechanical strength, in which the tensile strength is about three times higher than the control PVA. Additionally, the membrane demonstrates outstanding fire-resistant performances with an 80% reduction of peak heat release rate than pure PVA. More importantly, this unique membrane with random conductive networks possesses an outstanding EMI shielding efficiency near 41 dB much greater than traditional composite, which meets the requirement of high-efficiency EMI shielding applications. This article displays a novel strategy to fabricate a nanostructured polymer membrane with outstanding fire resistance, electrical conductivity, and mechanical strength, targeted and designed for high-efficiency EMI shielding applications.

Flexible, Ultralight, and Mechanically Robust Waterborne Polyurethane/Ti3C2Tx MXene/Nickel Ferrite Hybrid Aerogels for High-Performance Electromagnetic Interference Shielding.

Flexible, ultralight, and mechanically robust electromagnetic interference (EMI) shielding materials are urgently demanded to manage the increasing electromagnetic radiation pollution, but it remains a great challenge to simultaneously achieve ultralight yet mechanically robust properties while retaining high-efficiency EMI shielding performance. Herein, we fabricate a novel waterborne polyurethane/Ti3C2Tx MXene/nickel ferrite (WPU/MXene/NiFe2O4) hybrid aerogel by constructing a strong chemical bonding interaction between an NCO-terminated WPU prepolymer and hydroxyl functionalized MXene nanosheets. The resultant aerogels exhibit remarkable lightweight and mechanical properties, particularly high compressive stress far exceeding that of other MXene-based and WPU-based porous materials. Furthermore, synergistic effects of the oriented porous architecture and the multiphase skeleton endow the hybrid aerogels with a high X-band EMI shielding effectiveness (SE) of 64.7 dB at a low density of ∼38.2 mg/cm3. The corresponding specific SE value achieves 1694-3124 dB·cm3/g, and the SSE/d is up to 15,620 dB·cm2/g, surpassing that of most reported EMI shielding materials. Importantly, this aerogel, with excellent electromagnetic radiation protection effects and shielding reliability, is highly promising for long-term and effective EMI shielding service in various application environments.