Flexible Electromagnetic Interference Shielding Research Articles

Flexible conductive polymer composite film with sandwich-like structure for ultra-efficient and high-stability electromagnetic interference shielding

Flexible electromagnetic interference (EMI) shielding films with the merits of light-weight, flexibility, and high EMI shielding performance are the essential materials for the consumer electronics and communication products. Herein, we construct a hybrid conductive network based on the electrospinning thermoplastic polyurethane (TPU) film loaded with different dimensional conductive fillers, including 0D FeCl3, 1D carbon nanotube (CNT) and 2D graphene nanosheet (GN), which fabricate a flexible, light-weight, and ultra-efficient EMI shielding composite film. In specific, the electrospinning porous TPU film is firstly anchored by CNTs assisted by ultrasound to generate the porous TPU/CNT film. Thereafter, the as-prepared porous TPU/CNT film is filtered by GN/CNT/FeCl3 solution to generate a double-layer GN/CNT/FeCl3@TPU/CNT film. Finally, another porous TPU/CNT film is sealed onto the GN/CNT/FeCl3@TPU/CNT film by hot-pressing, which fabricates a sandwiched TPU/CNT@GN/CNT/FeCl3@TPU/CNT composite film. It is interesting to note that the composite film possesses the ultrahigh EMI shielding value (56.0 dB at 10.0 GHz) in the X-band (8.2-12.4 GHz) with high flexibility, excellent mechanical properties, long-term durability (acid-base environment resistance and stability after 1000 bends), as well as high thermal conductivity (6.53 W/(m K)). This work proposes a simple but efficiency strategy to design the flexible EMI shielding film with ultra-high performance and outstanding durability.

Shear-Induced Fabrication of Cellulose Nanofibril/Liquid Metal Nanocomposite Films for Flexible Electromagnetic Interference Shielding and Thermal Management.

To address electromagnetic interference (EMI) pollution in modern society, the development of ultrathin, high-performance, and highly stable EMI shielding materials is highly desired. Liquid metal (LM) based conductive materials have received enormous amounts of attention. However, the processing approach of LM/polymer composites represents great challenges due to the high surface tension and cohesive energy of LMs. In this study, we develop a universal one-step fabrication strategy to directly process composites containing LMs and cellulose nanofibrils (CNFs) and successfully fabricate the ultrathin, flexible, and stable EMI shielding films with an average specific EMI shielding efficiency (EMI SE) value of 429 dB/mm and small thickness of only 70 μm in the wide frequency range of 8.2-18 GHz. In addition, the resulting films also exhibit excellent mechanical performance and flexibility, which endow the film with the ability to withstand repeated folding, bending, and folding into complex shapes without producing cracks or fractures. Besides, the resulting films display excellent thermal conductivity with a λ of 4.90 W/(m K) and an α of 3.17 mm2/s. Thus, the presented approach shows great potential in fabricating advanced materials for EMI shielding applications.

Succulent-Inspired Implicit Structural Change for Smart "ON/OFF" Switchable and Flexible EMI Shielding Coating.

Modern miniaturized intelligent electronics call for smart switchable and flexible electromagnetic interference (EMI) shielding material for highly precise applications. However, most switchable EMI shielding materials are based on an explicit structural change. Herein, we report a succulent-inspired smart switchable MXene (WR-MXene) coating film realized by inner implicit structural change, which benefits from the insertion of our reversible large-cavity yolk-shell biomicrospheres. The novel switchable yolk-shell biomicrospheres contain a soft N-isopropylacrylamide (PNIPAM) hydrogel core, an "ON/OFF" switchable cavity (over 30% volume fraction), and a porous polydopamine (p-PDA) shell. The yolk-shell biomicrospheres can be obtained by a facile two-step polymerization and a simple drying-dehydration treatment. Because of the "ON/OFF" switchable void space brought by the smart biomicrospheres and conductive framework of MXene, an optimized ultralight and flexible WR-MXene coating film (vWR-coating film) showed both large switchable change (over 60 dB) and extraordinary EMI shielding effectiveness, reaching 95 and over 50 dB in the whole X band (8.2-12.4 GHz). These novel reversible yolk-shell biomicrospheres and the succulent-inspired switchable coating films are promising for smart flexible wearable devices and many advanced multifunctional systems needing dynamic real-time response.

Flexible Embedded Metal Meshes by Sputter-Free Crack Lithography for Transparent Electrodes and Electromagnetic Interference Shielding.

A facile and novel fabrication method is demonstrated for creating flexible poly(ethylene terephthalate) (PET)-embedded silver meshes using crack lithography, reactive ion etching (RIE), and reactive silver ink. The crack width and spacing in a waterborne acrylic emulsion polymer are controlled by the thickness of the polymer and the applied stress due to heating and evaporation. Our innovative fabrication technique eliminates the need for sputtering and ensures stronger adhesion of the metal meshes to the PET substrate. Crack trench depths over 5 μm and line widths under 5 μm have been achieved. As a transparent electrode, our flexible embedded Ag meshes exhibit a visible transmission of 91.3% and sheet resistance of 0.54 Ω/sq as well as 93.7% and 1.4 Ω/sq. This performance corresponds to figures of merit (σDC/σOP) of 7500 and 4070, respectively. For transparent electromagnetic interference (EMI) shielding, the metal meshes achieve a shielding efficiency (SE) of 42 dB with 91.3% visible transmission and an EMI SE of 37.4 dB with 93.7% visible transmission. We demonstrate the highest transparent electrode performance of crack lithography approaches in the literature and the highest flexible transparent EMI shielding performance of all fabrication approaches in the literature. These metal meshes may have applications in transparent electrodes, EMI shielding, solar cells, and organic light-emitting diodes.

Flexible, Transparent and Conductive Metal Mesh Films with Ultra-High FoM for Stretchable Heating and Electromagnetic Interference Shielding.

Despite the growing demand for transparent conductive films in smart and wearable electronics for electromagnetic interference (EMI) shielding, achieving a flexible EMI shielding film, while maintaining a high transmittance remains a significant challenge. Herein, a flexible, transparent, and conductive copper (Cu) metal mesh film for EMI shielding is fabricated by self-forming crackle template method and electroplating technique. The Cu mesh film shows an ultra-low sheet resistance (0.18 Ω □-1), high transmittance (85.8%@550nm), and ultra-high figure of merit (> 13,000). It also has satisfactory stretchability and mechanical stability, with a resistance increases of only 1.3% after 1,000 bending cycles. As a stretchable heater (ε > 30%), the saturation temperature of the film can reach over 110°C within 60s at 1.00V applied voltage. Moreover, the metal mesh film exhibits outstanding average EMI shielding effectiveness of 40.4dB in the X-band at the thickness of 2.5μm. As a demonstration, it is used as a transparent window for shielding the wireless communication electromagnetic waves. Therefore, the flexible and transparent conductive Cu mesh film proposed in this work provides a promising candidate for the next-generation EMI shielding applications.

Carbon felt from acrylic dust bags as flexible EMI shielding layer and resistive heater

Carbon felt is widely used due to its lightweight and conductive nature. However, limited research has been conducted regarding the tension applied during its preparation. This study aims to explore the influence of different loading tensions during the carbonization process on the properties of acrylic-based carbon felts. Enhanced flexibility, lower shrinkage and improved mechanical and electrical properties were found for the samples obtained in the edge loading mode. Subsequently, the performance of carbon felts in electromagnetic interference (EMI) shielding and resistive heating was studied. The carbon felts achieved a notable EMI shielding effectiveness of 55 dB. The specific shielding effectiveness values are significantly higher than other reported materials due to their low density and high porosity. Moreover, the carbon felts displayed commendable electrical heating performance through high heating rates and superior heating efficiency. Lastly, the structural stability was assessed via self-designed bending experiments. Good stability of the resistance and heating behavior of the carbon felts across multiple bending cycles was observed. With low manufacturing costs, good stability and air permeability, the flexible carbon felt is expected to be widely used for barrier applications and wearable electronics.

Electromagnetic interference shielding of flexible carboxymethyl cellulose/MWCNT@Fe3O4 composite film with ultralow reflection loss

Nowadays, various high-performance electromagnetic interference (EMI) shielding materials have enormous application potential in electronic field. However, traditional EMI shielding materials often have high conductivity, resulting in the serious mismatch between the impedance of the material surface and the free space, which will cause a large amount of reflection of electromagnetic (EM) waves, leading to secondary reflection pollution. In this paper, we report a novel flexible EMI shielding composite film with extremely low reflection loss and efficient EM wave absorption, which was prepared by assisted self-assembly based on simple vacuum filtration using carboxymethyl cellulose as the matrix and MWCNT@Fe3O4 synthesized by chemical coprecipitation as the composite functional filler. By adjusting the Fe3O4 coating degree of MWCNTs in the filler, the composite film achieved the construction of a conductive network with high Fe3O4 content. Benefit by the good adaptability of conductivity and magnetic permeability, the composite film has good impedance matching ability and microwave absorption performance. The reflection loss of the composite film with the thickness of 28 μm in the X-band was only 0.23 dB, accounting for 1.7 % of the total loss. This work provides new insights for the development of EMI materials and effective mitigation secondary EM wave reflection pollution.

Porous polypyrrole Nanotube-Based Organohydrogels: Versatile materials for robust electromagnetic interference shielding in harsh environments

Wearable and multi-functional electromagnetic interference (EMI) shielding materials are an inevitable trend in order to cope with increasingly complex practical applications. In the present work, polypyrrole nanotube (PNT)-based organohydrogels (POGs) with excellent electromagnetic shielding effectiveness (SE) were synthesized through a facile sol–gel strategy. The obtained POGs offer distinct shielding performance, anti-drying, anti-freezing, plasticity and recyclable ability. The POG with a 20 wt% PNTs filling exhibits a SET of 63.6 dB in the X-band at a thickness of 2.0 mm. After being placed at ambient temperature for 30 days and − 40 ℃ for 4 h, its SE values still retained at 50.3 dB and 59.3 dB, respectively. Moreover, after being immersed in the solvents, the POG (left in the air for 30 days) can recover flexibility and 92 % of its original EMI shielding performance. Importantly, crushing the fully dried organohydrogels into the powder and placing it again in the solvents fully restores its flexibility and EMI shielding properties. The glorious shielding and mechanical characteristics can be ascribed to the superior conductivity of PNTs and the highly crosslinked stable network of PVA, as well as the further enhancement of the crosslinked network by cellulose nanofibers. In addition, ​sensors based on POGs can effectively detect human movement and strain deformations. This work thus provides fresh insight into exploring the sustainability of flexible and wearable EMI shielding materials for handling extreme environments.

Robust, ultrathin and flexible electromagnetic interference shielding paper designed with all-polysaccharide hydrogel and MXene

An effective strategy was demonstrated to design an electromagnetic interference (EMI) shielding paper via a facile surface treatment on paper. TEMPO-oxidized cellulose nanofibers (TOCN) were first integrated with Ti3C2Tx MXene, and subsequently cast onto a filter paper with cationic guar gum (CGG) in a sequential way. TOCN and CGG generated a self-assembling hydrogel and formed a MXene-containing hydrogel film on top of the filter paper. The hydrogel film enhanced the tensile strength (9.49 MPa) of composite paper, and resulted in a 17 % increase as compared to the control. The composite paper containing 80 mg MXene (namely, 2.07 mg·cm−2) showed a conductivity of 3843 S·m−1 and EMI shielding effectiveness (EMI SE) of 49.37 dB. Furthermore, the 2-layer assembled TC-M 80 hydrogel composite paper achieved an EMI SE of 73.99 dB. Importantly, this composite paper showed higher EMI SE and lower thickness than a lot of reported materials. The presence of TOCN and CGG also protected MXene against several solvents and the incorporation of polydimethylsiloxane (PDMS) further improved the durability of the composite paper. This work provides a novel and simple strategy to design robust, ultrathin and flexible EMI shielding materials, and it might also inspire other work in paper-based functional materials.

Multilayer Ti3C2Tx MXene/graphene oxide/carbon fiber fabric/thermoplastic polyurethane composite for improved mechanical and electromagnetic interference shielding performance

The development of flexible electronics has placed higher demands on electromagnetic interference (EMI) shielding materials, especially in terms of mechanical properties. Herein, a novel composite with excellent mechanical and EMI shielding properties was developed. The electrohydrodynamic atomization deposition approach was used to deposit Ti3C2Tx MXene and graphene oxide (GO) nanosheets on carbon fiber fabric (CFf) surface, then they were assembled layer by layer with thermoplastic polyurethane (TPU) and thermoformed at high temperature to obtain MG/f-CFf/TPU composite. When the MXene/GO content increases, the mechanical performance of the composite is improved, mainly owing to the formation of chemical bonds and the presence of mechanical interlocking and van der Waals forces. Specifically, the tensile strength and interlaminar shear strength of the composite reach 140.98 MPa and 54.67 MPa, increasing by 72.45 % and 52.92 %, respectively. Benefitting from the unique lamellar structure, the maximum EMI-SE of MG/f-CFf/TPU composite is 38.29 dB. Besides, the MG/f-CFf/TPU composite also displays outstanding EMI-SE stability after 3000 times folding cycles. The flexible MG/f-CFf/TPU composite may provide more guidelines for the design of next-generation flexible EMI shielding materials.

Strong, hydrophobic, and transparent wood film decorated with MXene/silver nanowire for electromagnetic interference shielding and electrothermal conversion

Facing the continuous development and expansion of electronic devices and consequently increasing severe electromagnetic pollution, new requirements are put forward for electromagnetic interference (EMI) shielding materials, such as high transparency, mechanically robust, and flexibility. However, developing bio-based electromagnetic shielding materials that meet the above requirements remains challenging. Herein, a bio-based transparent wood prepared by delignification and TEMPO-mediated oxidation was used as the substrate, on which a durable hybrid conductive network containing MXene, silver nanowire (AgNW), and hydrophobic regents was assembled to prepare the multifunctional transparent film. The EMI shielding effect value of the obtained hydrophobic MXene/AgNW-decorated transparent wood (H-MATW) film was 31.5 dB with a corresponding transparency of 31.7%, which ascribing to excellent electroconductivity of the MXene/AgNW hybrid conductive network. Moreover, the tensile strength of H-MATW is as high as 406.5 MPa, attributed to the dense structure and strong hydrogen bonds between the cellulose chains in the transparent wood substrate. Furthermore, it exhibited tunable and low-pressure driving electrothermal conversion performance, reaching a temperature of 91 °C at only 4 V voltage. This work reports on bio-based candidate EMI shielding transparent film that can be used in visual windows and smart devices, providing a new pathway for developing flexible EMI shielding and electrothermal conversion materials.

Flexible free-standing BixSey@C/PEDOT:PSS thermoelectric composite film with high-performance electromagnetic interference shielding

Due to the component advantages and structural features, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS) based inorganic–organic composite films shows huge application potential in various fields. However, there are few reports on the bi-functions of thermoelectric (TE) and electromagnetic interference (EMI) shielding for the PEDOT:PSS-based functional films. Herein, metal–organic frameworks (MOFs)-derived BixSey@C sheets with average size about ∼ 7.32 μm are obtained via the solvothermal reaction and selenization pyrolysis treatment, and then flexible free-standing BixSey@C/PEDOT: PSS (BSCP) composite films are obtained by a feasible vacuum filtration combined with cold pressing treatment, using different contents of BixSey@C content as inorganic component. Micrometer BixSey@C sheets are uniformly dispersed in the PEDOT:PSS matrix constructing bi-functional composite films with unique layered structure. When the MOFs-derived BixSey@C content is 70%, BSCP-70 composite film gets a power factor of 11.23 μW m−1 K−2 at 340 K. Meanwhile, the BSCP-70 composite film reaches the highest average total EMI shielding effectiveness (SET) value of 45.0 dB at only 41.9 μm thickness at X-band. Based on multi-physical properties of MOF-derived BixSey@C and PEDOT:PSS, flexible BixSey@C/PEDOT:PSS composite films display good application potentiality in the flexible TE devices and EMI shielding protection.

Ultrathin and flexible MXene-contained electromagnetic interference shielding composite paper designed with a protective hydrogel film

MXene-contained paper is a good choice to design ultrathin and flexible electromagnetic interference (EMI) shielding materials. However, the deficiencies in strength and stability of MXene-contained paper impede its practical applications. Herein, a composite paper was proposed to address the problems, in which a filter paper was modified with a three-layer structured surface via a facile layer-by-layer coating procedure. Specifically, the TEMPO-oxidized cellulose nanofibers (TOCN)/cationic starch (CS)/MXene gel layer and TOCN/MXene nacre structure layer ensured the good EMI shielding and mechanical performances of the composite paper, while the uppermost TOCN/CS hydrogel film layer mainly protected MXene. The composite paper achieved an EMI SE of 40.3 dB at a thickness of merely 0.1894 mm (SE/t value of ca. 212.8 dB mm−1, SSE/t values of ca.13216 dB cm2 g−1) and the total MXene dosage was 20 g m−2. Its tensile strength could be up to 11.7 MPa while the original filter paper was 6.4 MPa. Four pieces of this composite papers could be easily packed together to attain an EMI SE of nearly 70 dB. Importantly, the hydrogel film layer efficiently protected the MXene and maintained the EMI shielding performance of the composite paper when immersed in different liquids including water, HCl (1 M) and ethanol, due to the dense and compact structure of hydrogel film layer. This work provides a practical way to develop ultrathin, flexible and durable EMI shielding materials.

Highly flexible, PEDOT:PSS-polyvinylpyrrolidone coated carbon nanofiber-polydimethylsiloxane composite for electromagnetic interference shielding

Lightweight, flexible and portable electronics, and wearable devices are recognized as the next-generation electronic devices. Rapid growth in the usage of such devices will add to electromagnetic interference (EMI) or EM pollution in an alarming magnitude. Hence, lightweight, hydrophobic, and flexible EMI shielding materials capable of effectively reducing EMI are urgently required. The present work reports fabrication of poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) and polyvinylpyrrolidone (PVP) coated, carbonized electrospun polyacrylonitrile (PAN) nanofiber (CNF) and their flexible polydimethylsiloxane (PDMS) composites. The material showed excellent EMI shielding effectiveness of 44 dB in the frequency range of 8–26.5 GHz with a thickness of 0.06 mm due to the synergetic effect of CNF matrix, PEDOT: PSS, and PVP. It also exhibited a high absolute EMI SE of 5678 dB cm2 g−1 with low loading of PEDOT:PSS-PVP. Here, PEDOT:PSS-PVP/CNF shows EMI shielding through an absorption dominated mechanism rather than reflection. These findings indicate the potential of these composites as thin, flexible, hydrophobic, and lightweight EMI shielding materials for practical applications.

Nanostructured Films of Ordered Fe Nanowires for High-Performance Transparent Electromagnetic Interference Shielding

Although metal nanowires (NWs), such as silver NWs, are ideal materials for flexible transparent electromagnetic shielding films, the challenge of obtaining absorptive shielding films with high transmittance and shielding efficiency (SE) still exists. To address this issue, this study used iron nanowires (Fe NWs) with excellent microwave absorbing properties to construct structures with ordered NW distributions. A series of polyethylene terephthalate (PET)/Fe NWs/poly (3,4-ethylenedioxythiophene) (PEDOT) electromagnetic interference (EMI) shielding films were prepared using the magnetic-field-induced orientation. The results demonstrate that the ordered Fe NW network structure can effectively overcome the problem of the trade-off between light transmittance and EMI SE. Specifically, at a Fe NW surface density of 201.78 mg/m2, the ordered PET/Fe NWs/PEDOT films demonstrated a 49.06% increase in light transmittance and a 32.94% increase in EMI SE (19.37 dB), compared to the films with randomly distributed Fe NWs. Furthermore, constructing a double-layer Fe NW network with a stagger angle of 45° at the same surface density increased the EMI SE by 73.2% relative to the monolayer-ordered Fe NW structure, reaching an SE value of 33.54 dB, while maintaining almost unchanged light transmittance. Additionally, the PET/Fe NWs/PEDOT films maintain 97.4% of EMI performance after 3000 bending cycles. Overall, this study provides a new approach for creating high-performance flexible transparent EMI shielding films.

Flexible bilayer Ti3C2Tx MXene/cellulose nanocrystals/waterborne polyurethane composite film with excellent mechanical properties for electromagnetic interference shielding

To address electromagnetic wave (EMW) pollution, the development of ultrathin and flexible electromagnetic shielding materials is essential. High electromagnetic interference (EMI) shielding performance while retaining robust mechanical properties remains a challenging hurdle. In this work, bilayer structured MXene/CNC/WPU (MCW-X) composite films were fabricated via alternating filtration assisted by vacuum. On the one hand, a conductive network is formed between CNC and MXene nanosheets, which enhances the electrical conductivity of the composite film as well as the stable water-oxidation stability. On the other hand, the interaction between WPU and MXene nanosheets increases the sliding between the layers of MXene nanosheets, hence enhancing the tensile strength and toughness. Meanwhile, the incorporation of CNC and WPU into MXene nanosheets increases the interlayer spaces of the composite films, optimizes impedance matching, and boosts the EMI shielding performance. MCW-4.5 sample composite (CNC 20 wt%) exhibits excellent electrical conductivity of 606.1 S/cm, resulting in a high-performance EMI shielding of 54.2 dB in X-band with a thickness of 35 µm. Meanwhile, it exhibits exceptional mechanical properties (elastic modulus of 3652.70 MPa, tensile strength of 52.2 MPa). Consequently, MCW-X composite films have a significant utilization potential in the field of green, ultrathin, and flexible EMI shielding.

Ti3C2Tx MXene/polyimide composites film with excellent mechanical properties and electromagnetic interference shielding properties

With the development of electronic products to miniaturization and high frequency, high-performance flexible electromagnetic interference (EMI) shielding materials are urgently needed to deal with electromagnetic pollution. Two-dimensional transition metal carbide/polyimide (Ti3C2Tx MXene/PI) films were synthesized by in situ polymerization and a simple scratch method in this paper. The Ti3C2Tx MXene nanosheets give the films good EMI shielding effectiveness (SE) and electrical conductivity. Specifically, the film with a thickness of 0.11 mm (Ti3C2Tx content of 30 wt%) exhibits an EMI SE of 34.73 dB and a specific EMI SE (SE/thickness) of 315.73 dB/mm in the frequency range of 8.2–12.4 GHz (X-band). In addition, the films have a tensile strength of 67.58 MPa, and a high decomposition temperature of 510 ℃ in N2 atmosphere. Therefore, we believe that the prepared Ti3C2Tx/PI films with good comprehensive performance have enormous potential in the field of lightweight and flexible EMI shielding materials.

Carbon nanotube films embedded with Cu@C nanocubes for electromagnetic interference shielding

AbstractFlexible carbon tube films for electromagnetic interference (EMI) shielding are assembled by mixing the well‐aligned Cu@C core‐shell nanocubes with multi‐walled carbon nanotubes (MWCNTs). The Cu@C core‐shell nanocubes are achieved by the thermal pyrolysis of polyvinylpyrrolidone (PVP) coating on Cu2O nanocubes. With the optimal PVP concentration of 1.5 mg/mL, the Cu@C/MWCNTs composite film with ultra‐thin thickness (52.2 μm) displays good conductivity of 12.5 S cm−1 and excellent specific EMI shielding value of 510.73 dB mm−1, which is higher than the pure MWCNTs film (439.50 dB mm−1) under the same weight condition. Moreover, the 1.5 mg/mL‐Cu@C/MWCNTs composite film exhibits highly mechanical repeatability after being bended for 10,000 cycles. The carbon layers protecting metal nanoparticles can partly replace precious carbon nanotubes to construction highly flexible composite film with anticipated electrical conductivity, which have a good application prospect for thin, lightweight and flexible EMI shielding fields.

Flexible Multilayered Poly(vinylidene fluoride)/Graphene-Poly(vinylidene fluoride) Films for Efficient Electromagnetic Shielding

Developing flexible electromagnetic interference shielding (EMI SE) materials is an effective strategy to protect humans from being harmed by electromagnetic radiation from electronic devices. Though the EMI SE property of such materials as graphene can exceed 100 dB, it remains a challenge to achieve high-efficiency EMI SE performance while having excellent flexibility to allow them to be wearable. Herein, we designed theoretically and fabricated experimentally the flexible multilayer structure of the poly(vinylidene fluoride)/graphene-poly(vinylidene fluoride) (PVDF/GNP-PVDF) composite films. The experimental results show that the film thickness and layer number play an important role in determining the EMI SE performance, and the multilayer film with a thickness of 0.3 mm and a layer number of 6 exhibits not only high EMI SE performance (69.7 dB on average in X-band) but also excellent flexibility and stability (98.85% EMI SE retention after bending of 60° for 1000 cycles). The theoretical study via COMSOL software matching well with the experimental data reveals that multiple reflection and absorption of electromagnetic waves between layers is responsible for the high EMI SE performance of the PVDF/GNP-PVDF multilayer film at a relatively low thickness that ensures flexibility. This work highlights the significance of designing the multilayer architecture via theoretical simulation for improving the EMI SE performance and also demonstrates the high EMI SE application prospect of PVDF/GNP-PVDF films in wearable electronic devices.

Fabrication of Ni-Encapsulated Carbon Tube/Poly(dimethylsiloxane) Composite Materials for Lightweight and Flexible Electromagnetic Interference Shielding Material.

The exploration of flexible and lightweight electromagnetic interference (EMI) shielding materials with excellent shielding effectiveness, as a means to effectively alleviate electromagnetic pollution, is still a tremendous challenge. This paper proposes a conducting material named the textured Ni-encapsulated carbon tube, which can be applied in EMI shielding material by being inserted in the center of a poly(dimethysiloxane) (PDMS) polymer. We demonstrated that Pd2+ could be absorbed by the active groups on the plant fiber surface to catalyze the reduction of Ni2+ as a catalytic center by means of a textured Ni-encapsulated plant fiber. Owing to the outstanding heat-conducting capability of the Ni coating, the inner plant fiber was carbonized and attached to the Ni-tube inside the surface during annealing. To be precise, the textured Ni-encapsulated C tube was fabricated successfully after annealing at 300 °C. On further increasing the annealing temperature, the C tube disappeared gradually with the Ni coating being oxidized to NiO. Of note, the C tube acted as a support layer for the external Ni coating, providing sufficient mechanical strength. When combined with the coating PDMS layer, a flexible and lightweight EMI shielding material is fabricated successfully. It displays an outstanding EMI shielding effectiveness of 31.34 dB and a higher specific shielding efficiency of 27.5 dB·cm3/g, especially showing excellent mechanical property and flexibility with only 2 mm thickness. This study provides a new method to fabricate outstanding EMI shielding materials.