Excellent Electromagnetic Interference Research Articles

Mussel-like carbon fiber/MnO2 nanosheet heterostructures for mechanically strong carbon fiber/polyamide composites with excellent electromagnetic interference shielding

In order to construct carbon fiber (CF) reinforced polyamide 6 (PA6) composites with both excellent mechanical properties and electromagnetic interference (EMI) shielding properties, in this paper, a multiscale coating of PDA-MnO2 is constructed on the CF surface based on the in-situ growth process of polydopamine (PDA) and δ-phase manganese dioxide (δ-MnO2) nanosheets. Interestingly, the introduction of PDA not only improves the yield and the crystal regularity of MnO2 nanosheets, but also enables the strength of CF to be maintained. The interlayer shear strength and interfacial shear strength of the modified CF/PA6 composites are increased by 19.45% and 37.45%, respectively, compared with those of the desized CF/PA6 composites. Meanwhile, the introduction of MnO2 nanosheets also improves the EMI shielding performance of the composites to commercial standards. The interfacial enhancement and EMI shielding mechanisms of the composites are elaborated, which enriches the theoretical system of CF composites for multifunctional applications.

Nanofiber derived MXene composite paper for electromagnetic shielding and thermal management

Despite the urgent demands in protecting wearable electronics from electromagnetic interference (EMI) in various conditions, it remains challenging to attain mechanically robust and flexible materials with both excellent EMI shielding and thermal managing performance. Herein, we report MXene composite paper that can provide multifunction with superior mechanical properties. To construct a hierarchical composite with 2D/0D reinforcements, the MXene paper is fabricated by hot pressing of electrospun Poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) nanofibers incorporated with MXene nanosheets and carbon black nanoparticles. Due to the laminated structure connected by nanoparticles, the flexible composite paper shows remarkable mechanical strength and fatigue resistance that can provide stable EMI shielding effectiveness of 500 dB/mm even after 10000th cyclic rolling. Moreover, the high in-plane electrical conductivity and out-of-plane thermal conductivity allow a fast electrothermal heating and cooling behavior, which qualifies the MXene paper as multifunctional surface for wearable electronics.

Multifunctional wearable Spider-Silk Inspired fabric for personal protection in extreme environments

Personal protective equipment (PPE) plays a vital role in healthcare, industry, and military settings, offering essential protection against various environmental hazards. However, the growing environmental challenges and demand for multifunctional integration make developing PPE that outperforms traditional single-function equipment a significant challenge. Herein, we present a flexible and wearable sandwich-structured film, fabricated by integrating an MXene core layer with Gd(OH)3/TPU outer layers through electrospinning and vacuum filtration process, simultaneously offering neutron and electromagnetic interference (EMI) shielding, energy harvesting, and thermal management. Mimicking spider silk's crystalline and amorphous regions, the outer layers integrate Gd(OH)3 nanorods into TPU nanofibers, thereby enhancing hydrogen bonding and achieving a high tensile strength of 22.94 MPa. Extensive hydrogen-bonding interactions firmly bind the MXene conductive core layer to the gadolinium-rich magnetic outer layers, providing excellent neutron (μ = 22.95 cm−1) and EMI shielding (SE = 35.1 dB). Additionally, the film also functions as a triboelectric nanogenerator (TENG), capturing kinetic energy to power low-voltage electronic devices, reducing reliance on external power in harsh settings. Remarkably, its superior Joule heating capability rapidly reaches various temperature (up to 78.5 ℃) by regulating external voltage to meet diverse user requirements. This study paves the way for future advancements in the realm of multifunctional PPE.

Ultrathin alternating multilayered silver nanowire-coated electrospinning films for excellent electromagnetic interference shielding and robust mechanical properties

Developing an ultra-thin flexible polymer film with simultaneously excellent electromagnetic interference (EMI) shielding performance and satisfactory mechanical property is still urgently demanded but challenging for integrated and miniaturized electronics. Herein, alternating multilayered silver nanowire-coating polyvinyl alcohol/ferroferric oxide@silver nanowires (PVA/Fe3O4@AgNW) composite films were successfully fabricated through spraying AgNWs on electrospinning PVA/Fe3O4 films, followed by hot pressing the alternately stacked monolayer PVA/Fe3O4 and PVA/Fe3O4@AgNW films in total of 6 layers. Stemming from superior conductive AgNW networks, alternating multilayered PVA/10-Fe3O4@10-AgNW composite film exhibits the prominent electrical conductivity of 1.5 × 105 S/m. Noteworthily, 6-layered PVA/10-Fe3O4@10-AgNW composite film with a thickness of 30 μm displays excellent EMI shielding effectiveness (SE) of 80.8 dB, on account of the unique alternating multilayered architectures and synergistic effect of conductive AgNWs and magnetic Fe3O4. Furthermore, 6-layered PVA/10-Fe3O4@10-AgNW film possesses satisfactory tensile strength (16.7 MPa) as well as superb flexibility (The fracture strain is 200.6 %). This effort sheds a new avenue for ultrathin flexible electrospinning films with both high EMI SE and remarkable flexibility, which has potential application in intelligent, wearable, and portable electronics.

Lightweight polyimide/silica aerogel composite foams and their derived carbon foams for excellent flame retardancy, thermal insulation and EMI shielding performance

Multifunctional porous materials demonstrate ubiquitous applications in the fields of flame retardancy, thermal insulation and electromagnetic interference (EMI) shielding. In this work, a series of lightweight polyimide/silica aerogel (PIF/SiA) foams with exceptional thermal stability, flame retardancy and thermal insulation performance were prepared by employing microwave-assisted foaming and thermal imidization treatment, using polyester ammonium salt/silica aerogel (PEAS/SiA) powders as the derivative precursors. The limiting oxygen index and fire growth rate reached as high as 58.2% and as low as 0.1 kW/(m2·s) for PIF/SiA composite foams, respectively, which was a result of the formation of micro/nano multi-scale pore structure of PIF skeleton and the “pearl-necklace-like” skeletal network of nano SiA. In addition, the PIF/SiA composite foams exhibited excellent thermal insulation and infrared stealth performance, which demonstrate a potential for long service life in fire protection use. Furthermore, the carbonized PIF/SiA (i.e., PICF/SiA) foams possessed enhanced mechanical (improvement of 117.6%) and EMI shielding performance (specific EMI shielding effectiveness: 8541.9 dB/(g/cm2)) when compared with the original PIF/SiA composite foams. To sum up, a facile method was proposed to fabricate multifunctional PIF-based composite foams and their derived carbon foams for flame retardancy, thermal insulation and EMI shielding applications in high-end engineering sectors.

Nickel-Fe3O4@Graphene coated lightweight carbonized wood for efficient electromagnetic interference shielding

The miniaturization and integration of electronic equipment promote electromagnetic effect radiation pollution more and more serious. The lightweight, renewable electromagnetic interference (EMI) shielding materials is urgently needed. This study developed a high temperature carbonization, Fe3O4@Graphene impregnation, and electroless Ni technique to construct a carbonized wood composite with strong EMI shielding performance using sustainable natural wood as the raw material. The Fe3O4@Graphene is distributed throughout the carbonized wood to provide the conductivity and magnetism of the reinforced composite material, and provide more interfaces to increase the dielectric loss and magnetic loss, thereby exhibiting excellent EMI shielding performance. The results show that at low thickness (2 mm) and ultra-low density (0.284 g/cm3), the CWN-7 composite exhibits excellent EMI shielding effectiveness of up to 84.2 dB in the whole X-band (8.2–12.4 GHz). At the same time, it has extraordinary compressive strength and good thermal insulation performance. This study offers a different method for creating composite multifunctional electromagnetic shields out of carbonized green wood.

Investigation of alignment and layup optimization of recycled carbon fiber mats on mechanical and electromagnetic shielding properties of composites

AbstractExcellent recycled carbon fiber (rCF) was obtained using a thermally activated oxide semiconductor process. An alignment device was manufactured based on wet‐laid technology. It was used to investigate the effect of various alignment nozzle parameters on the degree of alignment of rCF mats. The mechanical, electrical conductivity and EMI shielding properties of composites reinforced by rCF mats with different layup structures were analyzed. The results showed that the optimal alignment parameters for rCF aligned mats included a convex nozzle shape, a nozzle diameter of 3 mm, a nozzle channel length of 50 mm, a nozzle up‐and‐down diameter ratio of 7:1, a nozzle departure height of 20 mm. These settings achieved a preferential alignment degree (PAD) of 93.07%. The design of layup structures for rCF mats with optimized fiber alignment fully exploits the material's anisotropic characteristics. The rCF‐0/EP composite material exhibited the highest tensile strength (195.45 MPa), while the rCF‐04/EP composite material not only demonstrated the highest flexural strength (247.95 MPa) but also showed excellent electromagnetic interference (EMI) performance (47.97 dB). The results of the research laid a theoretical foundation and provides scientific guidance for high‐value reuse of rCF.Highlights Utilized rCF as a reinforcing material for CFRP composites. Preparation of rCF aligned mats with high PAD. Effect of different layup structures on rCF aligned mat reinforced composites. rCF aligned mats improve mechanical properties and EMI properties of composites.

Sandwich-Structured Mxene/Waste Polyurethane Foam Composites For Highly Efficient Electromagnetic Interference, Infrared Shielding and Joule Heating.

Electromagnetic interference (EMI) shielding and infrared (IR) stealth materials have attracted increasing attention owing to the rapid development of modern communication and military surveillance technologies. However, to realize excellent EMI shielding and IR stealth performance simultaneously remains a great challenge. Herein, a facile strategy is demonstrated to prepare high-efficiency EMI shielding and IR stealth materials of sandwich-structured MXene-based thin foam composites (M-W-M) via filtration and hot-pressing. In this composite, the conductive Ti3C2Tx MXene/cellulose nanofiber (MXene/CNF) film serves as the outer layer, which reflects electromagnetic waves and reduces the IR emissivity. Meanwhile, the middle layer is composed of a porous waste polyurethane foam (WPUF), which not only improves thermal insulation capacity but also extends electromagnetic wave propagation paths. Owing to the unique sandwich structure of "film-foam-film", the M-W-M composite exhibits a high EMI shielding effectiveness of 83.37dB, and in the meantime extremely low emissivity (22.17%) in the wavelength range of 7-14µm and thermal conductivity (0.19W m-1 K-1), giving rise to impressive IR stealth performance at various surrounding temperatures. Remarkably, the M-W-M composite also shows excellent Joule heating properties, capable of maintaining the IR stealth function during Joule heating.

Wearable EMI Shielding Composite Films with Integrated Optimization of Electrical Safety, Biosafety and Thermal Safety.

Biomaterial-based flexible electromagnetic interference (EMI) shielding composite films are desirable in many applications of wearable electronic devices. However, much research focuses on improving the EMI shielding performance of materials, while optimizing the comprehensive safety of wearable EMI shielding materials has been neglected. Herein, wearable cellulose nanofiber@boron nitride nanosheet/silver nanowire/bacterial cellulose (CNF@BNNS/AgNW/BC) EMI shielding composite films with sandwich structure are fabricated via a simple sequential vacuum filtration method. For the first time, the electrical safety, biosafety, and thermal safety of EMI shielding materials are optimized integratedly. Since both sides of the sandwich structure contain CNF and BC electrical insulation layers, the CNF@BNNS/AgNW/BC composite films exhibit excellent electrical safety. Furthermore, benefiting from the AgNW conductive networks in the middle layer, the CNF@BNNS/AgNW/BC exhibit excellent EMI shielding effectiveness of 49.95dB and ultra-fast response Joule heating performance. More importantly, the antibacterial property of AgNW ensures the biosafety of the composite films. Meanwhile, the AgNW and the CNF@BNNS layers synergistically enhance the thermal conductivity of the CNF@BNNS/AgNW/BC composite film, reaching a high value of 8.85W m‒1 K‒1, which significantly enhances its thermal safety when used in miniaturized electronic device. This work offers new ideas for fabricating biomaterial-based EMI shielding composite films with high comprehensive safety.

Superhydrophobic stretchable conductive composite textile with weft-knitted structure for excellent electromagnetic interference shielding and Joule heating performance

Conductive composite textiles (CCTs) as multifunctional integrated platform provide an effective path for developing flexible electromagnetic interference (EMI) shielding composites. However, conventional CCTs suffer from EMI shielding performance failure or the loss of textile's intrinsic properties under large tensile strain. Hence, in this work, a stretchable EMI shielding CCT that retains the inherent attributes of textile is proposed via weft-knitting and in-situ chemical Ag deposition. The complete and continuous silver nanoparticles (AgNPs) conductive networks bring excellent conductivity (38560 S/m) and ultrahigh EMI shielding performance (80.1 dB) in unstretched state. When tensile strain is applied, the fibers are gradually straightened from flexural state within 40 % strain, and then begin to be stretched at bigger strains, which benefits from the weft-knitting structure. Therefore, the conductive networks on the fiber surfaces are well protected from damage in the initial 40 % strain range, resulting in a stable EMI shielding performance (51.7 dB) even after 1000 cycles of 100 % tensile strain. Crucially, the CCT preserves good air permeability, softness and lightness even though a series of modifications and tensile strains are applied. Other than the EMI shielding perforamnce, the excellent superhydrophobicity (the contact angle of 158°) imparts the textile with the capability to tackle complex environments easily. Moreover, the textile can readily be heated to 73.4 °C at a low voltage of 0.5 V, showing outstanding Joule heating performance. Even after a long period of heating (3600 s), the textile maintains superior thermal stability, indicating potential applications in wearable heaters. In brief, this multifunctional CCT has excellent comprehensive properties and is expected to further expand the applications of EMI shielding textiles.

Robust ultrahigh electromagnetic interference shielding effectiveness based on engineered structures of carbon nanotube films

High-performance electromagnetic interference (EMI) shielding materials with ultrathin, flexible, and pliable mechanical properties are highly desired for high-end equipments, yet there remain large challenges in the manufacture of these materials. Here, carbon nanotube film (CNTF)/copper (Cu) nanoparticle (NP) composite films are fabricated via a facile electrodeposition method to achieve high electromagnetic shielding efficiency. Notably, a CNTF/Cu NP composite film with 15μm thickness can achieve excellent EMI shielding efficiency of ∼248 dB and absolute EMI shielding effectiveness as high as 2.17×105 dB cm2 g-1, which are the best values for composite EMI shielding materials with similar or greater thicknesses. These engineered composite films exhibit excellent deformation tolerance, which ensures the robust reliability of EMI shielding efficiency after 20,000 cycles of repeated bending. Our results represent a critical breakthrough in the preparation of ultrathin, flexible, and pliable shielding films for applications in smart, portable and wearable electronic devices, and 5G communication.

Flexible multilayer MXene/Polyimide composite film with excellent electromagnetic interference shielding and photothermal conversion performance

The development of flexible, thin, multifunctional materials represents a strategic advancement for the creation of next-generation wearables that offer both electromagnetic shielding and thermal management. This study introduces the fabrication of a multilayer MXene/polyimide (MXene/PI) composite film, demonstrating significant electromagnetic shielding effectiveness (EMI SE) and photothermal conversion efficiency through a layer-by-layer casting technique. When the MXene content is 29.7 wt%, the alternating multilayer MXene/PI composite film can reach a high EMI SE of 23.3 dB at 0.26 mm thickness, and when the MXene content is 45.7 wt%, the EMI SE can reach a maximum of 40.7 dB, which has a significant advantage over other materials. This superior performance exceed that of alternative materials, owing to the multilayer MXene construction that magnifies electromagnetic wave reflection losses. Furthermore, the film displays a rapid and sensitive photothermal response under laser irradiation, achieving temperatures up to 93°C at a 0.5 W/cm2 density. Impressively, at 0.4 W/cm2, it maintains a stable long-term saturation temperature over 40 cycles, showing its potential in applications such as photothermal sensors, personal heating, and muscle protection.

Highly conductive carbon nanotubes-boron nitride-thermoplastic polyurethane composite thin films with ultra broadband and efficient electromagnetic interference shielding up to 110 GHz and heat dissipation abilities

The miniaturization and integration of electronic devices have led to an increased accumulation of heat, which can disrupt normal functioning. Their functionalities are also severely affected when they are exposed to the abundant electromagnetic interference (EMI) resulting from the rapid development of fifth-generation telecommunication technology extended to mmWaves and sixth-generation telecommunication frequencies up to 110 GHz. Therefore, it is urgent to develop composite materials with excellent EMI shielding effectiveness and heat dissipation abilities. Herein, we have fabricated an all-in-one thin film composite using carbon nanotubes (CNT), boron nitride (BN), and thermoplastic polyurethane (TPU) through a layer-by-layer casting method to create a composite supported by hydrogen bonding with impressive EMI shielding and heat dissipation properties. The high electrical conductivity of the CNT-BN-TPU composite resulted in the highest EMI shielding effectiveness, ranging from 90.66 dB in Ka-band to 79.8 dB in W-band, at a thickness of 100 μm, with absorption efficiency of 83.07 % at 34 GHz and 80.85 % at 100 GHz, respectively. The composite demonstrated excellent heat dissipation, thanks to its outstanding out-of-plane thermal conductivity, which reached 1.971 W/mK. We believe that our proposed method for producing an all-in-one composite thin film with excellent EMI shielding and thermal management capabilities could be a useful approach for the next generation of smart electronic devices.

Electromagnetic interference shielding composite aerogels with asymmetric structures developed in aid of neural network

Along with the increasingly serious electromagnetic interference (EMI) pollution, it is in urgent need of exploiting high-performance EMI shielding materials. However, the conventional experimental methods always require a series of tedious preparation and characterization processes, resulting in the long period and high cost. Herein, a fully connected neural network (FCNN) was applied to aid in exploiting silver nanowires/waterborne polyurethan/multi-walled carbon nanotubes (AgNWs/WPU/MWCNTs) EMI shielding aerogels with asymmetric structures to optimize new material evolution and reduce experiment burden. Firstly, the special AgNWs/WPU/MWCNTs aerogels were fabricated with various MWCNTs content (0 wt%, 2 wt%, and 4 wt%) and AgNWs mass (10 mg, 20 mg, 30 mg, and 40 mg) via a combination of directional freezing and spraying procedures, leading to 12 distinct samples. AgNWs/WPU/MWCNTs aerogels hold excellent EMI shielding properties and absorption-dominant shielding mechanism. The experimental EMI shielding effectiveness (SE) data at different frequency were leveraged to establish, train, and test the FCNN model based on Adam optimizer (Adam-FCNN). It is worth noting that Adam-FCNN model predictions are in good accordance with the EMI SE of the physically measured samples, with the lowest root mean square error RMSE of 0.7899, the highest correlation coefficient (R) of 0.9895, and excellent computational efficiency and reliability. Moreover, Adam-FCNN can accurately prognosticate EMI SE of unobtained AgNWs/WPU/MWCNTs aerogels in mechanics-intuitions to reduce repeated preparation and characterizing conditions. Thereby, Adam-FCNN soft model approach opens significant potential for alleviating the experimental burden, accelerating the discovery of innovative materials, and exploring the complex mechanism.

Multi-interfacial bridging engineering of flexible MXene film for efficient electromagnetic shielding and energy conversion

Accompanied by the progressive development of electronic equipment, excellent electromagnetic interference (EMI) shielding materials display a satisfying prospect in protecting electronic devices against electromagnetic pollution/radiation, while integrating energy conversion. Heretofore, it remains a conundrum to availably construct thin films with multi-interfacial bridging engineering as multifunctional shielding devices. To effectively achieve electromagnetic wave attenuation and integrate energy conversion, a co-mixed vacuum-assisted filtration strategy is designed to synthesize Au@MXene/cellulose nanocrystal/dodecylbenzenesulfonic acid-doped polyaniline (AMCP) films. Profited from the interfacial engineering, the total EMI shielding effectiveness (SE) can be increased by 27 % with the highest value of 67.9 dB. MXene with localized surface plasmon resonance characteristics gives the composite films good energy conversion performance, that is, the composite film can be rapidly heated up to 100 °C under the irradiation of an infrared lamp, and its surface temperature remains stable after continuous irradiation. Additionally, the infrared emissivity is as low as 0.173 within the 8–14 μm, which is necessary to adapt various application scenarios. Therefore, it is reliable that the AMCP films constructed by multicomponent offer a facile strategy for MXene-based EMI shielding devices with integration characteristics.

Efficient preparation of polydimethylsiloxane‐based phase change composites with sandwich structure

AbstractWith the rapid development of portable electronic devices, there is an urgent need for the multifunctional composites like excellent electromagnetic interference (EMI) shielding performance, mechanical property, and thermal management capabilities. Here, due to the low thermal conductivity of phase change materials (PCMs), a sandwich structure carbon nanotube/phase change microcapsule/carbon nanotube (CNT/PMC/CNT (CPC)) film was prepared by vacuum‐assisted filtration (VAF) method. CNT, PMC, and cellulose nanocrystal (CNC) were used as functional fillers. The addition of CNCs was used to improve the mechanical performance of CPC film. Compared with PMC‐CNC (PC) film, CPC film with sandwich structure prevented leakage phenomenon efficiently. Subsequently, the use of ultrasonic‐assisted forced infiltration (UAFI) successfully infiltrated polydimethylsiloxane (PDMS) matrix in the filler skeleton to obtain CNT/PMC/CNT/PDMS (CPCP) composites. When filler mass ratio (CNT: CNC and PMC: CNC) reached 10:1, the thermal conductivity of CPCP composites was 2.32 W/(m·K) and total EMI shielding effectiveness (EMI SET) of it with 0.38 mm thickness reached 37.46 dB at 12.4 GHz. Besides, these sandwich composites exhibited the good mechanical properties and heat storage capacity. And we systematically observed the impact of different addition amounts of PC homogeneous dispersing solution on phase change ability of CPCP10:1 composites. In summary, CPCP phase change composites with sandwich structure shows potential application prospect in thermal management materials with EMI shielding of electronic devices.Highlight The sandwich structure CPCP composites prepared by the combination of VAF and UAFI method, showing superior thermal conductivity and phase change ability. CPCP has excellent EMI shielding performance, which can meet the need of TMMs with EMI shielding performance. Compared with same thickness PC film, sandwich CPC film can prevent leakage phenomenon efficiently.

In situ construction of efficient electromagnetic function Graphene/PES composites based on liquid phase exfoliation strategy

Although graphene nanosheets (GNs) with huge specific surface area and exceptional electrical properties exhibit attractive practical prospect in the realm of electromagnetic function materials, how to optimize the distribution states of GNs in matrix is still a challenge. In this work, the suspension of GNs was prepared directly via an efficient liquid-phase exfoliation (LPE) process in N-octyl-2-pyrrolidone (NOP). Thanks to the dissolution of polyether sulfone (PES) in NMP and NOP solvent, the GNs/PES composites were in-situ prepared via a facile solution blending in combination with evaporation process. The “function units” of the mesoscopic micro-cluster structure assembled by GNs during the solvent evaporation process contribute to optimized impedance matching characteristics and loss capabilities as well as excellent electromagnetic wave (EMW) absorbing performance of the as-constructed GNs/PES electromagnetic composites. Particularly, the as-prepared sample G-P-9 with a graphene content of as low as 9.0 wt% exhibits outstanding EMW absorbing performance in the whole ranges of tested frequency (8.2–12.4 GHz) and temperature (293–453 K) with a minimum reflection loss (RL) of −52.7 dB. Besides, the in-situ self-assemble GNs/single-walled carbon nanotubes (GNs/SWCNT) film with pre-constructed three-dimensional interpenetrating conductive network exhibits excellent electromagnetic interference (EMI) shielding effectiveness (SE) of about 5.1 × 104 dB cm2 g−1. The present approach would be applicable to construct high-performance electromagnetic functional materials and broaden the application prospect of high-integrity graphene nanosheets.

High-Compressive, Elastic, and Wearable Cellulose Nanofiber-Based Carbon Aerogels for Efficient Electromagnetic Interference Shielding.

Developing excellent electromagnetic interference (EMI) shielding materials with robust EMI shielding efficiency (SE), high mechanical performance, and multifunctionality is imperative. Carbon materials are well recognized as promising alternatives for high-performance EMI shielding, but their high brittleness greatly hampers their applications. In this work, a cellulose nanofiber/reduced graphene oxide-glucose carbon aerogel (C-CNFs/rGO-glu) with high compression, elasticity, and excellent EMI shielding performance was fabricated by directional freeze-drying followed by carbonization. Specifically, the height and stress retention are 88% and 90.9%, respectively, after 100 cycles of compression release at a high strain of 70%. The electromagnetic shielding effectiveness of the aerogels reached 67.5 dB and presented an absorption-dominant shielding mechanism with a 97.5% absorption loss ratio. Further, the carbon aerogel could capture subtle electrical signals to monitor different human behaviors and showed excellent heat insulation and infrared stealth performance.

Two birds with one stone: High electromagnetic interference shielding effectiveness and high thermal conductivity of ternary polyvinyl alcohol/graphene/ carbonyl iron nanocomposite films

Gaining brilliant flexible, easily-processable, bendable, low-density and high electrical conductivity (σ) materials with an excellent electromagnetic-interference (EMI) shielding performance is urgently needed in the fields of aerospace, aircraft, military, wearable and portable electronic industries. Therefore, the growing desire towards miniaturizing and developing high-frequency electronics is increasing incredibly today and grabbing much attention, however, they cause extreme heat accumulation and EM radiations that affect their performances as well as their hazardous effects on human health. So, polymer nanocomposites with high thermal conductivity (k) and EMI shielding effectiveness (SE) synchronously are urgently required to consume the generated heat and blocks the EM waves. Herein, poly(vinyl alcohol)/graphene nanosheets/carbonyl iron (PVA/GRx/CIR0.1-x) nanocomposite films are introduced as a new alternative candidate for EMI shielding applications with high in-plane k//, high mechanical functions, and EMI SET performance. The synergistic effect of GR and CIR on EMI shielding functions, thermal stability, mechanical properties, electrical features, and surface morphology has been explored. The increase in GR(x) amounts provides continuous GR layers and dense networks for conducting electrons and heats, provides the films with an admirable k// and total SE (SET) synchronously. Particularly, the PVA/GR0.08/CIR0.02 films have shown an σ of 1.72 Sm−1, a large SET of 32.94 dB and a specific SE (SSE/t) of 4365 dBcm2g−1 due to the mutual role (effect) of both high electrical conductive graphene and high magnetic carbonyl iron in cancelling the magnetic and electric fields of the incident EM waves. Moreover, the layered structure of GR endows films with a high k// of 3.62±0.11 W/(m·K), which is 14-fold larger than that of green PVA. The high compatibility and fine dispersion of GR/CIR fillers endow the films with a high Young modulus of 2.16 GPa, which is 7-fold larger than that of green PVA. This work suggests a novel and feasible scheme for producing high EMI shielding and high thermal conductive polymeric films, which will have huge prospects in advanced technology such as electromagnetic (microwave) interference shielding, wearable, biological, smart fabrics, military technologies and electronic equipments.

In-situ growth of CuS on polyimide film to construct dense and continuous network: Achieving excellent electrothermal and EMI shielding performance

The performance of the electrothermal film is generally determined by conductive filler network. However, it is still challenging to construct a dense network of conductive fillers in the electrothermal film. In this work, we develop a simple and efficient method to construct a dense and continuous network via in-situ growth of CuS nanosheets on the surface of polyimide (PI) film with stable interfacial bonding. The obtained PI@CuS electrothermal film is further packaged by commercially available PTFE and PI tapes to achieve desirable surface hydrophobic self-cleaning function and stability for the use in different environments. By tuning the network density of CuS nanosheets, it imparts excellent electrothermal conversion efficiency and cycling stability to the PI@CuS film, whose surface temperature could rapidly ramp up over 200 °C at 8 V. The film also exhibits excellent photothermal performance, reaching close to 100 °C at 100 mW/cm2. The anti-icing/de-icing experiment shows that the icing time is prolonged significantly at low temperature and the melting time is reduced dramatically. Furthermore, the PI@CuS film also exhibits outstanding electromagnetic interference (EMI) shielding effectiveness of 57.1 dB with a thickness of only 80 μm, and excellent tensile strength of over 90 MPa. The in-situ growth strategy provides a novel route for the fabrication of the electrothermal film with excellent overall performance.