dB Cm2 Research Articles

In-situ assembly of polypyrrole onto heterocyclic aramid for high-strength, ultratough, durable, and multifunctional films

High-strength, ultratough, multifunctional polymer-based electromagnetic interference (EMI) shielding nanocomposite films have colossal application potential in artificial intelligence, 5G communications, and flexible electronics. In this work, a large-scale, high-strength, and ultratough heterocyclic aramid@polypyrrole (HA@PPy) composite film is developed via the in-situ loading of PPy onto the HA template. The synthesized films achieve remarkable mechanical properties and high electronic conductivity by using the template effect of HA to guide the assembly of conductive polymers. When the content of PPy is 45 wt%, the HA@PPy (HP45) film possesses excellent tensile strength (240.3 MPa), significant elongation at break (25.9 %), outstanding toughness (53.1 MJ m−3), and exceptional folding durability owing to strong hydrogen bond interaction between PPy and HA. Furthermore, thanks to the highly connected conductive paths formed by PPy, the HP45 film exhibits satisfactory EMI shielding effectiveness (EMI SE) of 45.5 dB and specific EMI SE of 14691.6 dB cm2 g−1 at an ultra-thin thickness (26.3 μm). The HP45 film also demonstrates excellent electromagnetic protection, electro-/photothermal deicing, thermal therapy, and flame retardancy applications. Therefore, high-performance and multifunctional HA@PPy films have substantial potential for widespread application in EMI shielding and thermal management.

Hydrophobic Multilayered PEG@PAN/MXene/PVDF@SiO2 Composite Film with Excellent Thermal Management and Electromagnetic Interference Shielding for Electronic Devices.

With the rapid development of electronic industry, it's pressing to develop multifunctional electromagnetic interference (EMI) shielding materials to ensure the stable operation of electronic devices. Herein, multilayered flexible PEG@PAN/MXene (Ti3C2Tx)/PVDF@SiO2 (PMF) composite film has been constructed from the level of microstructure design via coaxial electrospinning, coating spraying, and uniaxial electrospinning strategies. Benefiting from the effective encapsulation for PEG and high conductivity of MXene coating, PEG@PAN/MXene composite film with MXene coating loading density of 0.70mg cm-2 exhibits high thermal energy storage density of 120.77 J g-1 and great EMI shielding performance (EMI SE of 34.409dB and SSE of 49.086dB cm3 g-1) in X-band (8-12GHz). Therefore, this advanced composite film can not only help electronic devices prevent the influence of electromagnetic pollution in the X-band but also play an important role in electronic device thermal management. Additionally, the deposition of nano PVDF@SiO2 fibers (289±128nm) endowed the PMF composite film with great hydrophobic properties (water contact angle of 126.5°) to ensure the stable working of hydrophilic MXene coating, thereby breaks the limitation of humid application environments. The finding paves a new way for the development of novel multifunctional EMI shielding composite films for electronic devices.

Design of polyimide/carbon nanotube@Ag@polyimide/graphene composite aerogel for infrared stealth and electromagnetic interference protection

CHATGPT artificial intelligence is taking the world by storm, and countless electronic devices will generate massive amounts of electromagnetic interference (EMI). Hence, there is a pressing demand for materials exhibiting high thermal conductivity and superior EMI shielding effectiveness (SE). Thus, we construct a polyimide/carbon nanotube@Ag@polyimide/graphene (PCAPG) composite aerogel with porous, layered, and homogeneous structures in one, which provides a new idea for the multi-interface polarization interaction and special structure of anti-EMI materials. PCAPG has high thermal conductivity of ∼ 0.259 W (mK)-1 at 25 °C, excellent EMI SE of ∼ 90.28 dB and specific shielding effectiveness (SSE) of ∼ 940.42 dB cm3 g−1. The synergistic EMI attenuation mechanism of the PCAPG composite structure is analyzed using an aerogel unit. This composite aerogel provides a viable solution for infrared stealth, promoting heat dissipation from electronic components and reducing electromagnetic interference.

Roll-to-roll joule-heating to construct ferromagnetic carbon fiber felt for superior electromagnetic interference shielding

The effective safeguard from electromagnetic radiation damage via electromagnetic interference shielding (EMI) materials is crucial for diverse applications, especially in modern aerospace, medical, and human body protection endeavors. Despite great efforts have been made to surmount challenges encompassing scalability, sustainability and cost, the integrated and continuous production of large-area electromagnetic shielding materials remains unsolved for industrial-scale demands. Herein, we develop a cascaded methodology involving spray loading and Joule-heating for fabricating hybrid EMI fabric with superior efficiency, where ferromagnetic Fe3O4 nanoparticles are further successfully in situ deposition on ultralight carbon fiber felt (Fe3O4/FePc@CFF) in a roll-to-roll (R2R) manner. Fe3O4/FePc@CFF characterized by a surface density of only 64.76 g/m2, achieves specific shielding effectiveness per unit thickness (SSE/t) remarkable values of 9604 dB cm2 g−1 and 10947 dB cm2 g−1 within the X-band and Ku-band, respectively. Considering the high compatibility with assembly on flow line production, this research offers substantial development potential for further design and advancement of pivotal materials in the realm of electromagnetic protection.

Highly durable hollow sandwich MXene/h-AgNWs/ANF composite films for exceptional electromagnetic interference shielding performance

Multi-functional electromagnetic interference (EMI) shielding materials are crucial for advanced electronic devices, requiring low thickness, exceptional shielding performance, and stability, especially in extreme conditions. In this study, the hollow sandwich MXene/h-AgNWs/ANF (AMAgMA) composite films were fabricated via template sacrificing method and layer-by-layer vacuum assisted filtration. Specifically, the hollow MXene was created using PMMA as the template, together with AgNWs for the conductive layer, while ANF provided stability and high temperature resistance as the protective layer. The optimized EMI shielding efficiency (SE) reached 88.2 dB for a film thickness of 93 μm, with an SSE/t value of 18160 dB cm2·g−1, which was attributed to the hollow structure and continuous double conductive network design. Remarkably, EMI SE of the films maintained even after 70 days of exposure to oxidation, acid, alkali, salt, and ultrasonic treatment thanks to the sandwich design. Additionally, the composite films displayed excellent heat transfer and thermal stability (530 °C), alongside notable flame retardancy and self-extinguishing properties. The superior EMI shielding performance and stability in extreme environments suggest a promising application potential in advanced electronics.

A popcorn-inspired strategy for compounding graphene@NiFe2O4 flexible films for strong electromagnetic interference shielding and absorption

Compounding functional nanoparticles with highly conductive and porous carbon scaffolds is a basic pathway for engineering many important functional devices. However, enabling uniform spatial distribution of functional particles within a massively conjugated, monolithic and mesoporous structure remains challenging, as the high processing temperature for graphitization can arouse nanoparticle ripening, agglomerations and compositional changes. Herein, we report a unique “popcorn-making-mimic” strategy for preparing a highly conjugated and uniformly compounded graphene@NiFe2O4 composite film through a laser-assisted instantaneous compounding method in ambient condition. It can successfully inhibit the unwanted structural disintegration and mass loss during the laser treatment by avoiding oxidation, bursting, and inhomogeneous heat accumulations, thus achieving a highly integrated composite structure with superior electrical conductivity and high saturated magnetization. Such a single-sided film exhibits an absolute shielding effectiveness of up to 20906 dB cm2 g−1 with 75% absorption rate, superior mechanical flexibility and excellent temperature/humidity aging reliability. These performance indexes signify a substantial advance in EMI absorption capability, fabrication universality, small form-factor and device reliability toward commercial applications. Our method provides a paradigm for fabricating sophisticated composite materials for versatile applications.

Fe3O4@CNTs/WPU@CNF aerogel/Ag foam composites with a double-layer structure for absorption-dominated electromagnetic shielding performance

With the popularity of electronic devices, absorption-dominated multilayered electromagnetic shielding materials are increasingly attractive due to the effective decrease of second pollution compared to the traditional homogeneous electromagnetic shielding materials. However, the design of multilayered structure and strong interface adhesion of functional composite while keeping light weight and practical use is not readily to realize. Therefore, we propose herein a double-layer aerogel/foam composite electromagnetic shielding composite. The absorption layer is made by a nanocellulose (CNF)@waterborne polyurethane (WPU) aerogel, in which magnetic nano iron tetraoxide (Fe3O4) joined with carbon nanotubes (CNTs) to optimize the impedance matching. The reflection layer is a chemically silver-plated foam (AF) used to reflect the transmitted electromagnetic waves through its strong electrical conductivity, improving the overall ability of electromagnetic waves shielding and achieving enhanced electromagnetic shielding performance. The two layers are strongly combined by the adhesion of WPU without the use of adhesives. When the mass ratio of CNTs to Fe3O4 of 2:1 and the total mass fraction of 5 wt%, the EMI shielding efficiency of the composites reaches 62.81 dB in the X-band (8.2–12.4 GHz) at the thickness of 4 mm and the maximum value reaches a remarkable 76.63 dB at 1.17 GHz. The specific SE value of SSE/t reaches 1744.72 dB cm2 g−1. Thanks to the effect of AF layer, the average reflectivity is only 0.141, demonstrating an absorption-dominated shielding mechanism. In addition, the as-prepared composite material is remarkably flexible and deformation-resistant, with a density of only 0.0913 g cm−3 and can withstand approximately 85,000 times its own weight.

Multi-heterointerface integration in nitrogen-doped Ti3C2Tx@Fe3O4 nanocomposites for superior microwave absorption

Engineering a lightweight and thin microwave absorber through the design of multiple heterogeneous interfaces represents a significant challenge. Here, we synthesized a nitrogen (N)-doped Ti3C2Tx@Fe3O4 (N–Ti3C2Tx@Fe3O4) nanocomposite with a sandwich-like structure through a solvothermal approach using hydrazine hydrate as the N donor. The numerous Ti3C2Tx electron transfer pathways of Ti3C2Tx enable the realization of a hierarchical conduction network within N–Ti3C2Tx@Fe3O4. The introduction of defects through N doping and the integration of Fe3O4 with Ti3C2Tx are pivotal for enhancing the dipole polarization. The heterogeneous interfaces in N–Ti3C2Tx@Fe3O4, coupled with Fe3O4 components, substantially boost the electromagnetic wave (EMW) absorption performance of the composite. An optimal N integration and the loading of Fe3O4 in Ti3C2Tx result in an improved impedance matching of N–Ti3C2Tx@Fe3O4. The synergistic effect of the improved impedance matching and the strong EMW attenuation capability endow N–Ti3C2Tx@Fe3O4 with enhanced microwave absorption (MA) properties. Specifically, at a thickness of 1.04 mm, the composite exhibits the effective absorption bandwidth (3.92 GHz; 14.08–18.00 GHz), surpassing that of Ti3C2Tx. At a thickness of 0.98 mm, it exhibits a maximum reflection loss of −40.28 dB at 17.25 GHz, which substantially exceeds that of Ti3C2Tx. Furthermore, it shows a maximum Radar Cross Section reduction of 21.32 dB cm2. A cotton fabric was coated with N–Ti3C2Tx@Fe3O4, and it was found to exhibit enhanced heat conduction and dissipation, at rates 3.83 and 4.64 times greater than those of uncoated cotton, respectively. These results highlight the considerable potential of N–Ti3C2Tx@Fe3O4 nanocomposites for use in far-field applications. It is envisaged that the exceptional MA and thermal management properties of N–Ti3C2Tx@Fe3O4 nanocomposites will provide a novel avenue for crafting lightweight and thin EMW absorbing materials.

Strong and flexible MXene-based nanocomposite films for atomic oxygen resistance and electromagnetic interference shielding

MXene has garnered considerable attention as a promising candidate for multifunctional artificial materials, owing to its exceptional mechanical performance and superior electric conductivity. However, macroscopically layered films assembled by MXene nanosheets are usually accompanied by serious degradation of mechanical properties. Moreover, there is a notable paucity of investigations on MXene in low Earth orbit (LEO) environment. Inspired by the layered structure of nacre, we applied polyurethane (PU) as an interfacial crosslinking agent to improve the mechanical properties of MXene films. The optimized MXene/PU (MP) nanocomposite film exhibited a tensile strength of 298.02 MPa and a toughness of 13.81 MJ m−3, surpassing those of the pure MXene film by 260 % and 1300 %, respectively. The atomic oxygen (AO) erosion yield of MP was approximately one order of magnitude lower than that of commercial Kapton films, which was attributed to the shielding effect of MXene against AO attacks. Remarkably, the MP nanocomposite film demonstrated exceptional retention of tensile strength under various extreme conditions including AO irradiation, cryogenic-high temperature, cyclic thermal shock and hot water. Contributed by multi-layer structural design and high conductivity, the MP exhibited a high electromagnetic interference shielding effectiveness (EMI SE) of 48 dB and a specific SE divided by thickness (SSE/t) of 13,479 dB cm2 g−1 at the thickness of 20 μm. Consequently, the nacre-like MP nanocomposite film with exceptional mechanical properties and high-level functional performance holds substantial promise as a multifunctional space material for LEO environments.

A PVDF/MWCNTs/GO@MWCNTs/AgNWs bilayer structured composite film with ultra‐high EMI shielding and conductivity performance

AbstractElectromagnetic interference (EMI) shielding materials with easy processing, high electrical conductivity, and excellent absorption loss are urgently needed in aerospace, military stealth and portable electronic devices. In this study, a polyvinylidene fluoride/multi‐walled carbon nanotubes (PVDF/MWCNTs)‐3 wt% composite film prepared by simple solution mixing and polyethylene terephthalate (PET) nonwoven scraping method was used as the substrate, and the PVDF/MWCNTs/graphene oxide@multi‐walled carbon nanotubes (PVDF/MWCNTs/GO@MWCNTs) and PVDF/MWCNTs/GO@MWCNTs/silver nanowires (PVDF/MWCNTs/GO@MWCNTs/AgNWs) bilayer composite films were prepared by vacuum‐assisted filtration (VAF). When the amount of GO@MWCNTs was 20 mL, the conductivity of PVDF/MWCNTs/GO@MWCNTs film is 3.5 × 101 S m−1, the total EMI shielding effectiveness (EMI SET) was 15.5 dB and the EMI absorption efficiency (EMI SEA) was 10.7 dB, the specific EMI SE (SSE/T) was 539.5 dB/ dB/(cm−2 g). When the amount of AgNWs was 25 mL, the conductivity of PVDF/MWCNTs/GO@MWCNTs/AgNWs film with 0.47 mm thickness was 1.6 × 104 S m−1, the EMI SET was 69.1 dB, the EMI SEA was 61.1 dB, and the SSE/T was 2320.0 dB cm2 g−1. The results show that the absorption was played a dominant role in the EMI shielding mechanism of obtained films. The addition of GO@MWCNTs/AgNWs increases the electrical conductivity and EMI shielding performance of the film more than the addition of GO@MWCNTs. This is mainly because GO， MWCNTs and AgNWs formed a novel three‐dimensional conductive network structure inside the composite film due to their hydrogen bonding and van der Waals forces, which increases the carrier channels and promotes the interaction between the internal microcurrents and the electromagnetic waves, achieving the purpose of attenuating the electromagnetic waves. The obtained PVDF/MWCNTs/GO@MWCNTs/AgNWs film has good potential in EMI shielding in aerospace, military and electronic intelligence applications.Highlights Well‐dispersed and highly conductive GO@MWCNTs were prepared by hydrothermal synthesis. AgNWs with good conductivity and high aspect ratio were prepared. PVDF‐based bilayer composite films with novel 3D conductive network were prepared. The synergistic EMI shielding mechanism of the film is discussed.

A Journey from Structured Emulsion Templates to Multifunctional Aerogels

AbstractInterfacial jamming and assembly, facilitated by nanoparticle surfactant (NPS) complexation, demonstrate a remarkable efficacy in stabilizing multiphase systems, evident in structured liquid streams and structured Pickering emulsions. However, the utilization of structured liquid templates to tune multiple porosity levels of ultra‐flyweight aerogels is barely discussed. In this study, a structured Pickering emulsion is prepared through mixing an aqueous dispersion of graphene oxide (GO) with an organic (hexane) solution containing an active ligand. The emulsion is jetted into the same organic phase, resulting in “dual jamming”. This process produced worm‐like aerogels with porosity that can be precisely tailored at four different levels: i) voids between filaments, ii) cavities produced by evaporation of trapped hexane droplets, iii) pores generated from sublimation of water in the bulk of GO emulsion, and iv) microscopic regions trapped between GO flakes or fractures/holes within GO nanosheets. These aerogels exhibit ultra‐low density (1.67–2.3 mg cm−3), high compressibility, and shape recovery. The multi‐scale porosity, created by structural design, endows aerogels with a record‐level fluid sorption capacity (e.g., 615 g g−1 for chloroform). Additionally, the aerogels demonstrate an absorption‐dominant electromagnetic interference (EMI) shielding mechanism, achieving a remarkable specific EMI shielding (SSE/t) of 67 178 dB cm2 g−1.

In situ reduction of copper nanoparticles in porous carbonized wood for efficiently enhancing electromagnetic interference shielding performance

In this study, porous carbonized wood was used as the substrate, and a multi-layer composite of copper/carbonized wood/copper (Cu/CW/Cu) layer with light weight, flame retardancy, and efficient electromagnetic shielding effectiveness was prepared by electroless copper method. The results showed that the copper particles can be filled in the layered porous structure of the carbonized wood. The metal Cu layer was evenly covered on the surface of the whole carbonized wood, and the average surface roughness was 7.62 µm. The absorption peak at 2340 cm−1 was significantly enhanced, which proved that the increase of the number of electroless Cu on the carbonized wood surface promoted the improvement of Cu autocatalytic ability. After three depositions of Cu, the conductivity of the composite material reached 1154 S/cm, showing good electrical properties. The shielding effectiveness in the X-band from 8.2 to 12.4 GHz was up to 55.97 dB at low density (0.27 g/cm3). Specific shielding effectiveness SSE/t was as high as 581.69 dB cm2 g−1. Through the “absorption–reflection–absorption” path, high absorption and low reflection are achieved, shielding a large number of incident electromagnetic waves.

Popcorn-inspired preparation of carbon aerogel with nano-walls for electromagnetic shielding and thermal insulation

In this study, we devised a green and straightforward approach for fabricating carbon aerogels by heating dextrin, drawing inspiration from the popping mechanism of popcorn. The structure and morphology of the samples were intricately regulated through precise adjustments in the temperature and duration of the heat-treatment process, resulting in the formation of a carbon aerogel comprising nano-walls. Upon carbonisation at 2100 °C, the resultant carbon aerogel exhibited an exceptionally low density of approximately 0.029 g cm−3. Notably, the aerogel demonstrated excellent electromagnetic shielding performance, reaching a shielding effectiveness of approximately 57 dB and an impressive specific shielding effectiveness of 1965 dB cm3 g−1 with a thickness of 5 mm across the entire X band. Additionally, it displayed an ultra-low thermal conductivity of approximately 0.016 W m−1 K−1 and good thermal stability. These characteristics position carbon aerogels as promising materials with vast application potential in electromagnetic shielding and thermal insulation.

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 Sandwich-Shaped Cellulose Nanocrystals/Silver Nanowires/MXene Films Exhibit Efficient Electromagnetic-Shielding Interference Performance.

The electromagnetic pollution problem is becoming increasingly serious due to the speedy advance of electronic communication devices. There are broad application prospects for the development of flexible, wearable composite films with high electromagnetic interference (EMI)-shielding performance. The MX@AC composite films were prepared from MXene, silver nanowires (AgNWs) and cellulose nanocrystals (CNCs) with a sandwich structure. Benefiting from the upper and lower frame structure formed by winding 1D AgNWs and CNC, the tensile strength of the MX@AC was improved to 35 MPa (12.5 wt% CNC content) from 4 MPa (0 wt% CNC content). The high conductivity of MXene and AgNWs resulted in the MX@AC composite film conductivity up to 90,670 S/m, EMI SE for 90 dB, as well as SSE/t up to 7797 dB cm2 g-1. And the MX@AC composite film was tested for practical application, showing that it can effectively isolate electromagnetic waves in practical application.

Lightweight multifunctional electromagnetic shielding composites achieved by depositing Ag@MXene hybrid particles on wood-based aerogel

As electronic devices become more integrated into daily life, concerns about electromagnetic radiation pollution become more severe, despite the increased portability they offer. Designing a lightweight and multifunctional material that is environmentally friendly, thermally conductive, and electromagnetically shielded is urgently needed. In this work, novel composites were fabricated by incorporating Ag@MXene hybrid particles into the wood-based aerogel. Compared with the aerogels containing only Ag nanoparticles (AgNPs) or MXene, the Ag@MXene/W aerogel exhibited more homogeneous dispersion of unfolded MXene nanosheets and more AgNPs but higher porosity (97.1 %) and smaller density (0.047 g cm−3). Consequently, the Ag@MXene/W aerogel exhibited high compressibility and low energy dissipation, remarkable strain sensitivity, impressive electrical conductivity (33.9 S m−1) and specific electromagnetic shielding efficiency (5765.96 dB cm2 g−1), and high thermal conductivity (0.81 W m−1 K−1). The excellent comprehensive performances ensure that the aerogel has wide applications in various fields, including electromagnetic pollution protection, strain detecting, and thermal management, etc.

PMDI cross-linked rare earth/liquid metal reinforced ANF/MXene membranes for multifunctional electromagnetic interference shielding

With the miniaturization of electronic devices, the creation of efficient and lightweight electromagnetic interference (EMI) shielding materials is of imminent significance. In this context, we reported an electromagnetic shielding membrane with hydrophobic, antioxidative, and high temperature stability. The chemically cross-linked Aramid nanofibers (ANF)/MXene@Ga/Gd2O3 (CAMG) nanocomposite membranes exhibit a considerable tensile strength and possess exceptional flexibility. The CAMG shielding membranes demonstrate multiple heterogeneous interfaces and a magnetic-dielectric synergistic system, thereby effectively enhancing the absorption shielding efficiency, with the specific shielding effectiveness per unit volume (SSE/t) reaching 6788 dB cm2 g−1. Furthermore, the composite membranes demonstrate remarkable electrothermal capabilities, acting as pliable heaters with notable, swiftly replicable, and consistent electrothermal effects at reduced voltages. Additionally, they possess superior heat dissipation efficiency and ensure a uniform heat dispersion. The exceptional electromagnetic shielding performance and multifunctionality of the C-ANF/MXene@Ga/Gd2O3 shielding membranes imply their instructive relevance in next-generation fields such as flexible electronics and aerospace.

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.

Highly Conductive PEDOT:PSS Aerogels

AbstractPoly(3,4‐ethylenedioxythiophene):poly(4‐styrenesulfonate) (PEDOT:PSS) aerogel has attracted much attention in bioelectronics, electromagnetic shielding, and energy‐related systems due to its biocompatibility, intrinsic electronic conductivity, and favorable processability. However, fabrication of highly conductive and low‐density PEDOT:PSS aerogels is still challenging. In this work, highly conductive PEDOT:PSS aerogels are produced via ice‐templated pre‐assembly followed by a specially designed thawing process in H2SO4 solution. Upon optimization of heat and mass transfer during the thawing process, along with the unique ice template effect, the microstructure and thin walls of PEDOT:PSS frozen samples are well preserved. Importantly, the porous structure and thin walls facilitate diffusion of H2SO4 into polymer matrix, inducing phase separation of PEDOT:PSS, thus increasing PEDOT crystallinity and partially removing of PSS component. As a result, the as‐prepared pristine PEDOT:PSS aerogels exhibit a high electrical conductivity of 1200 ± 231 S m−1 along the freezing direction at a low density of 15.3 ± 1.5 mg cm−3, enhanced mechanical properties, and a competitive electromagnetic interference shielding efficiency of 25 115 dB cm2 g−1. Moreover, the compressed aerogels show good performances as active materials in symmetrical supercapacitors with thickness‐independent capacitance (maximum 2.1 F cm−2 at 1.0 mA cm−2) and in current collector‐free micro‐supercapacitors processed by laser carving.

Guar gum assisted synthesis of high‐quality silver nanoplates and their polyimide matrix nanocomposites for electromagnetic interference shielding applications

AbstractTwo‐dimensional (2D) silver nanoplates are chemically synthesized in the presence of guar gum – a naturally occurring biopolymer. The polymer directs anisotropic growth of silver nuclei into high aspect ratio nanoplates spanning 4500 ± 500 nm lateral length with thickness as small as 40 ± 10 nm. After a thorough investigation of the reaction parameters (temperature, precursor to reductant ratio, and polymer quantity) on the morphology of the product, a scalable synthetic protocol to achieve good yields (95%–98%) of highly pure (~100%) 2D silver nanoplates (AgNPls) in a facile, inexpensive, room temperature, aqueous phase chemical reaction of only about 5 min is devised. The optimized AgNPls induce appreciable conductivity of 5.5 ± 0.38 S/cm in polyimide at only 12 wt% loading. Consequently, the resulting polymer nanocomposite (containing 12 wt% AgNPls), at only 130 ± 15 μm thickness and 0.45 g/cm3 density, effectively blocks electromagnetic radiation in X‐band with a total shield effectiveness of about 10 dB resulting in substantially high specific shielding effectiveness and absolute shielding effectiveness of 22.48 and 1729.23 dB cm3 g−1, respectively. Additionally, the nanocomposites remain thermally stable up to 500°C in oxidative environment and possess an appreciably high storage modulus of 3.113 GPa at 50°C. These low‐density conductive polyimide films, therefore, present great prospects in shielding against electromagnetic interference under extreme conditions.