Highly Effective Electromagnetic Interference Shielding Materials based on Silver Nanowire/Cellulose Papers

Multifunctional Wearable Electronic Based on Fabric Modified by PPy/NiCoAl-LDH for Energy Storage, Electromagnetic Interference Shielding, and Photothermal Conversion

With the rapid advancement of electronic technology, traditional textiles are challenged to keep up with the demands of wearable electronics. It is anticipated that multifunctional textile-based electronics incorporating energy storage, electromagnetic interference (EMI) shielding, and photothermal conversion are expected to alleviate this problem. Herein, a multifunctional cotton fabric with hierarchical array structure (PPy/NiCoAl-LDH/Cotton) is fabricated by the introduction of NiCoAl-layered double hydroxide (NiCoAl-LDH) nanosheet arrays on cotton fibers, followed by polymerization and growth of continuous dense polypyrrole (PPy) conductive layers. The multifunctional cotton fabric shows a high specific areal capacitance of 754.72 mF cm-2 at 5 mA cm-2 and maintains a long cycling life (80.95% retention after 1000 cycles). The symmetrical supercapacitor assembled with this fabric achieves an energy density of 20.83 Wh cm-2 and a power density of 0.23 mWcm-2. Moreover, the excellent electromagnetic interference shielding (38.83 dB), photothermal conversion (70.2 °C at 1000 mW cm-2), flexibility and durability are also possess by the multifunctional cotton fabric. Such a multifunctional cotton fabric has great potential for using in new energy, smart electronics, and thermal management applications.

Recent advances in multifunctional electromagnetic interference shielding materials

Electromagnetic interference (EMI) shielding material is the most effective solution to protect electronic devices and human health from the harmful effects of electromagnetic radiation. The study of EMI shielding materials is intensifying in the constantly developing picture of the fourth industrial revolution. Many EMI shielding materials based on metal, carbon, emerging MXene materials, and their composites have been discovered to utilize the EMI shielding performance. However, a huge demand for compact and multi-functional devices requires the integration of new functions into EMI shielding materials. Multifunctional EMI shielding materials perform multiple functions beyond their main function of EMI shielding in a system due to their specific properties. The additional functions can either naturally exist or be specially engineered. This review summarizes the recent progress of cutting-edge multifunctional EMI shielding materials. The possibility of combining multifunction EMI shielding materials, such as strain sensing, humidity sensing, temperature sensing, thermal management, etc., and the difficulties in balancing EMI shielding performance with other functions are also discussed. Lastly, we point out challenges and propose future directions to develop research on multifunctional EMI shielding materials.

Bacterial Cellulose-Based Bandages with Integrated Antibacteria and Electrical Stimulation for Advanced Wound Management

Bandages for daily wounds are the most common medical supplies, but there are still ingrained defects in their appearance, comfort, functions, as well as environmental pollution. Here, novel bandages based on bacterial cellulose (BC) membrane for wound monitoring and advanced wound management are developed. The BC membrane is combined with silver nanowires (AgNWs) by using vacuum filtration method to achieve transparent, ultrathin (≈7 µm), breathable (389.98-547.79 g m-2  d-1 ), and sandwich-structured BC/AgNWs bandages with superior mechanical properties (108.45-202.35 MPa), antibacterial activities against Escherichia coli and Staphylococcus aureus, biocompatibility, and conductivity (9.8 × 103 -2.0 × 105  S m-1 ). Significantly, the BC/AgNWs bandage is used in the electrical stimulation (direct current, 600  microamperes for 1 h every other day) treatment of full-thickness skin defect in rats, which obviously promotes wound healing by increasing the secretion of vascular endothelial growth factor (VEGF). The BC bandage is used for monitoring wounds and achieve a high accuracy of 94.7% in classifying wound healing stages of hemostasis, inflammation, proliferation, and remodeling, by using a convolutional neural network. The outcomes of this study not only provide two BC-based bandages as multifunctional wound management, but also demonstrate a new strategy for the development of the next generation of smart bandage.

Highly Conducting Surface-Silverized Aromatic Polysulfonamide (PSA) Fibers with Excellent Performance Prepared by Nano-Electroplating

In this work, bilayer nanocoatings were designed and constructed on high-performance aromatic polysulfonamide (PSA) fibers for robust electric conduction and electromagnetic interference (EMI) shielding. More specifically, PSA fibers were first endowed with necessary electric conductivity via electroless nickel (Ni) or nickel alloy (Ni-P-B) plating. Afterward, silver electroplating was carried out to further improve the performance of the composite. The morphology, microstructure, environmental stability, mechanical properties, and EMI shielding performance of the proposed cladded fibers were thoroughly investigated to examine the effects of electrodeposition on both amorphous Ni-P-B and crystalline Ni substrates. The acquired results demonstrated that both PSA@Ni@Ag and PSA@Ni-P-B@Ag composite fibers had high environment stability, good tensile strength, low electric resistance, and outstanding EMI shielding efficiency. This indicates that they can have wide application prospects in aviation, aerospace, telecommunications, and military industries. Furthermore, the PSA@Ni-P-B@Ag fiber configuration seemed more reasonable because it exhibited smoother and denser silver surfaces as well as stronger interfacial binding, leading to lower resistance (185 mΩ cm-1) and better shielding efficiency (82.48 dB in the X-band).

Multifunctional Asymmetric Bacterial Cellulose Membrane with Enhanced Anti-Bacterial and Anti-Inflammatory Activities for Promoting Infected Wound Healing

An asymmetric wound dressing acts as a skin-like structure serves as a protective barrier between a wound and its surroundings. It allows for the absorption of tissue fluids and the release of active substances at the wound site, thus speeding up the healing process. However, the production of such wound dressings requires the acquisition of specialized tools, expensive polymers, and solvents that contain harmful byproducts. In this study, an asymmetric bacterial cellulose (ABC) wound dressing using starch as a porogen has been developed. By incorporating silver-metal organic frameworks (Ag-MOF) and curcumin into the ABC membrane, the wound dressing gains antioxidant, reactive oxygen species (ROS) scavenging, and anti-bacterial activities. Compared to BC-based wound dressings, this dressing promotes efficient dissolution and controlled release of curcumin and silver ions. In a full-thickness skin defect model, wound dressing not only inhibits the growth of bacteria on infected wounds but also regulates the release of curcumin to reduce inflammation and promote the production of epithelium, blood vessels, and collagen. Consequently, this dressing provides superior wound treatment compared to BC-based dressing.

Durable cellulose paper by grafting thiol groups and controlling silver deposition for ultrahigh electromagnetic interference shielding

Electromagnetic interference (EMI) shielding paper with durability and high effectiveness is of significant importance to long-term service for preventing EMI pollution. Herein, we report a practical method for preparing cellulose paper/Ag composite with outstanding durable and ultrahigh EMI shielding performance by electroless silver plating. The silver deposition process, the surface morphology, the silver content and conductivity of the composite can be controlled by varying the amount of N-acetyl-L-cysteine (NAC) grafted onto the cellulose fibers and ammonia amount for silver-ammonia complex formation. Moreover, the grafted NAC with thiol groups on cellulose can enhance the adhesion between silver and cellulose paper, meanwhile, NAC as the reducing agent can result in a more complete flower-shaped silver structure and reducing the reflection of electromagnetic waves in silver layer. The composite exhibited excellent conductivity, EMI shielding effectiveness (SE) up to 106 dB and outstanding durability. After 10,000 bending times and 60 abrasion cycles respectively, the electrical resistance of the composite only increased from 0.030 Ω/sq. to 0.041 Ω/sq. and 0.050 Ω/sq., and the EMI SE decreased to 102 dB and 105 dB.

Transparent and Flexible Composite Films with Excellent Electromagnetic Interference Shielding and Thermal Insulating Performance

As the working environment becomes more complex, the visualization of windows in electronic devices increasingly requires transparent and flexible electromagnetic interference (EMI) shielding films. There is a need for materials with EMI shielding properties, while maintaining excellent high light transmission and good thermal insulation. However, the preparation of such multifunctional materials remains challenging due to the respective mechanisms of action of the different properties. Herein, a multilayer structure strategy is proposed to fabricate transparent and flexible indium tin oxide (ITO)/silver nanowire (AgNW) composite films, achieving a multifunctional integration of high light transmission, strong EMI shielding, and good thermal insulation properties of the composite films. Simultaneously, the layered structure was designed and the potential optimization mechanism of the EMI shielding performance of the composite film was analyzed, providing great flexibility for the preparation of transparent composite films. The combination of excellent EMI shielding performance, outstanding near-infrared shielding performance, and high light transmittance makes the ITO/AgNW (IA) composite films promising for abundant potential applications.

Enhanced Electromagnetic Shielding and Thermal Management Properties in MXene/Aramid Nanofiber Films Fabricated by Intermittent Filtration

High-efficiency electromagnetic interference (EMI) shielding and heat dissipation synergy materials with flexible, robust, and environmental stability are urgently demanded in next-generation integration electronic devices. In this work, we report the lamellar MXene/Aramid nanofiber (ANF) composite films, which establish a nacre-like structure for EMI shielding and heat dissipation by using the intermittent filtration strategy. The MXene/ANF composite film filled with 50 wt % MXene demonstrates enhanced mechanical properties with a strength of 230.5 MPa, an elongation at break of 6.2%, and a toughness of 11.8 MJ·m³ (50 wt % MXene). These remarkable properties are attributed to the hydrogen bonding and highly oriented structure. Furthermore, due to the formation of the MXene conductive network, the MXene/ANF composite film shows an outstanding conductivity of 624.6 S/cm, an EMI shielding effectiveness (EMI SE) of 44.0 dB, and a superior specific SE value (SSE/t) of 18847.6 dB·cm²/g, which is better than the vacuum filtration film. Moreover, the MXene/ANF composite film also shows a great thermal conductivity of 0.43 W/m·K. The multifunctional MXene/ANF composite films with high-performance EMI shielding, heat dissipation, and joule heating show great potential in the field of aerospace, military, microelectronics, microcircuit, and smart wearable electronics.

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

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

Absorption-Dominant, Low-Reflection Multifunctional Electromagnetic Shielding Material Derived from Hydrolysate of Waste Leather Scraps

High-performance flexible conductive films are highly promising for the development of wearable devices, artificial intelligence, medical care, etc. Herein, a three-step procedure was developed to produce electromagnetic interference (EMI) shielding, Joule heating, and a hydrophobic nanofiber film based on hydrolysate of waste leather scraps (HWLS): (i) electrospinning preparation of the HWLS/polyacrylonitrile (PAN)/zeolitic imidazolate framework-67 (ZIF-67) nanofiber film, (ii) carbonization of the HWLS/PAN/ZIF-67 nanofiber film, and (iii) coating of the carbon nanofiber@cobalt (Co@CNF) nanofiber film with perfluorooctyltriethoxysilane (POTS). The X-ray diffraction results showed that metal nanoparticles and amorphous carbon had obvious peaks. The micromorphology results showed that metal nanoparticles were coated with carbon nanofibers. The conductivity and shielding efficiency of the carbon nanofiber film with 250 μm thickness could reach 45 S/m and 49 dB, respectively, and absorption values (A > 0.5) were higher than reflection (R) values for the Co@CNF nanofiber film, which indicated that the contribution of absorption loss was more significant than that of reflection loss. Ultrafast electrothermal response performances were also achieved, which could guarantee the normal functioning of films in cold conditions. The water contact angle of the Co@CNF@POTS nanofiber film was ∼151.3°, which displayed a self-cleaning property with water-proofing and antifouling. Absorption-dominant and low-reflection EMI shielding and electrothermal films not only showed broad application potential in flexible wearable electronic devices but also provided new avenues for the utilization of leather solid waste.

Recent Advances in Polymer Nanocomposites for Electromagnetic Interference Shielding: A Review

The mushrooming utilization of electronic devices in the current era produces electromagnetic interference (EMI) capable of disabling commercial and military electronic appliances on a level like never before. Due to this, the development of advanced materials for effectively shielding electromagnetic radiation has now become a pressing priority for the scientific world. This paper reviews the current research status of polymer nanocomposite-based EMI shielding materials, with a special focus on those with hybrid fillers and MXenes. A discussion on the theory of EMI shielding followed by a brief account of the most popular synthesis methods of EMI shielding polymer nanocomposites is included in this review. Emphasis is given to unravelling the connection between microstructures of the composites, their physical properties, filler type, and EMI shielding efficiency (EMI SE). Along with EMI shielding efficiency and conductivity, mechanical properties reported for EMI shielding polymer nanocomposites are also reviewed. An elaborate discussion on the gap areas in various fields where EMI shielding materials have potential applications is reported, and future directions of research are proposed to overcome the existing technological obstacles.

Graphene Reinforced Anticorrosion Transparent Conductive Composite Film Based on Ultra-Thin Ag Nanofilm

Transparent conductive films are widely used in electronic products and industrial fields. Ultra-thin Ag conductive nanofilm (ACF) was prepared on a soda lime silica glass (ordinary architectural glass) substrate with industrial magnetron sputtering equipment with AZO (Al₂O₃ doped ZnO) as the crystal bed and wetting layer. In order to improve the corrosion resistance and conductivity of the ACF, graphene nanosheets were modified on the surface of the ACF by electrospraying for the first time. The results show that this graphene modification could be carried out continuously on a meter scale. With the modification of the graphene layer, the corrosion rate of graphene-decorated ACF (G/ACF) can be reduced by 74.56%, and after 72 h of salt spray test, the conductivity of ACF samples without modification of graphene can be reduced by 34.1%, while the conductivity of G/ACF samples with modification of graphene can be reduced by only 6.5%. This work proves the potential of graphene modified ACF to prepare robust large-area transparent conductive film.

Recent Progress in Electromagnetic Interference Shielding Performance of Porous Polymer Nanocomposites—A Review

The urge to develop high-speed data transfer technologies for futuristic electronic and communication devices has led to more incidents of serious electromagnetic interference and pollution. Over the past decade, there has been burgeoning research interests to design and fabricate high-performance porous EM shields to tackle this undesired phenomenon. Polymer nanocomposite foams and aerogels offer robust, flexible and lightweight architectures with tunable microwave absorption properties and are foreseen as potential candidates to mitigate electromagnetic pollution. This review covers various strategies adopted to fabricate 3D porous nanocomposites using conductive nanoinclusions with suitable polymer matrices, such as elastomers, thermoplastics, bioplastics, conducting polymers, polyurethanes, polyimides and nanocellulose. Special emphasis has been placed on novel 2D materials such as MXenes, that are envisaged to be the future of microwave-absorbing materials for next-generation electronic devices. Strategies to achieve an ultra-low percolation threshold using environmentally benign and facile processing techniques have been discussed in detail.

A Perspective for Developing Polymer-Based Electromagnetic Interference Shielding Composites

The rapid development of aerospace weapons and equipment, wireless base stations and 5G communication technologies has put forward newer and higher requirements for the comprehensive performances of polymer-based electromagnetic interference (EMI) shielding composites. However, most of currently prepared polymer-based EMI shielding composites are still difficult to combine high performance and multi-functionality. In response to this, based on the research works of relevant researchers as well as our research group, three possible directions to break through the above bottlenecks are proposed, including construction of efficient conductive networks, optimization of multi-interfaces for lightweight and multifunction compatibility design. The future development trends in three directions are prospected, and it is hoped to provide certain theoretical basis and technical guidance for the preparation, research and development of polymer-based EMI shielding composites.

An Ultrastrong and Antibacterial Silver Nanowire/Aligned Cellulose Scaffold Composite Film for Electromagnetic Interference Shielding

Constructing multifunctional electromagnetic interference (EMI) shielding films with superior mechanical strength has sparked a lot of interest in the fields of wearable electronics. In this work, the conductive silver nanowires (AgNWs) were synthesized and impregnated into the highly aligned cellulose scaffold (CS) fabricated by wood delignification followed by hot-pressing and polydimethylsiloxane (PDMS) dipping processes to obtain the outstanding EMI shielding cellulosic film (d-AgNWs@CS-PDMS). The consecutively conductive pathway of AgNWs was constructed in the microchannels of the CS as a result of the hydrogen bonding between AgNWs and cellulose fibers, which is conducive to the reflection of incident EM waves. The higher degree of nanofiber alignment and the compact conductive network were improved by densification upon hot pressing, which endows the composite film with striking mechanical properties (maximum tensile strength of 511.8 MPa) and superb EMI shielding performance (shielding effectiveness value of 46 dB with a filler content of 21.6 wt %) at the X band (8.2-12.4 GHz). Moreover, the existence of an intensive AgNWs network and the introduction of the PDMS layer improve the hydrophobicity and antibacterial activity of the composite film, avoiding serious health concerns in the long-term wearing. These results demonstrate that the obtained d-AgNWs@CS-PDMS composite film has high potential as an EMI shielding material used for wearable devices.

Anisotropic cellulose nanofibril composite sponges for electromagnetic interference shielding with low reflection loss

With the development of the electronic industry bringing convenience to people, a series of caused electromagnetic pollution problems (e.g., electromagnetic interference (EMI)) have recently also become urgent tasks. In this work, an anisotropic composite sponge consisting of cellulose nanofibrils (CNFs) and chemical co-precipitated silver nanowire (AgNW)@Fe₃O₄ composites was successfully prepared. Due to the introduction of anisotropic structures and the synergistic effect among CNFs, AgNWs, and Fe₃O₄, this composite sponge exhibited low density (16.76 mg/cm³), good saturation magnetization (4.21 emu/g) and electrical conductivity (0.02 S/cm), and anisotropic EMI shielding ability. By adjusting the proportion (1:0.3) between AgNWs and Fe₃O₄ and their loading (0.15 vol%) inside the sponge, the reflection loss of the sponge with the improved interface impedance mismatch was only 2.3 dB, accounting for 7.2% of the total loss. It is expected to become a promising EMI shielding material, especially for effectively alleviating the secondary reflection EM pollution.

Hydrophobic, flexible electromagnetic interference shielding films derived from hydrolysate of waste leather scraps

With the rapid development of wireless telecommunication technologies, it is of fundamental and technological significance to design and engineer high-performance shielding materials against electromagnetic interference (EMI). Herein, a three-step procedure is developed to produce hydrophobic, flexible nanofiber films for EMI shielding and pressure sensing based on hydrolysate of waste leather scraps (HWLS): (i) electrospinning preparation of HWLS/polyacrylonitrile (PAN) nanofiber films, (ii) adsorption of silver nanowires (AgNWs) onto HWLS/PAN nanofiber films, and (iii) coating of HWLS/PAN/AgNWs nanofiber films with polydimethylsiloxane (PDMS). Scanning electron microscopy studies show that AgNWs are interweaved with HWLS/PAN nanofibers to form a conductive network, exhibiting an electrical conductivity of 10⁵ S m^-1 and shielding efficiency of 65 dB for a 150 μm-thick HWLS/PAN/AgNWs film. The HWLS/PAN/AgNWs/PDMS film displays an even better electromagnetic shielding efficiency of 80 dB and a water contact angle of 132.5°. Results from this study highlight the unique potential of leather solid wastes for the production of high-performance, environmentally friendly, and low-cost EMI shielding materials.

Transparent and Flexible Electromagnetic Interference Shielding Film Using ITO Nanobranches by Internal Scattering

A transparent and flexible film capable of shielding electromagnetic waves over a wide range of frequencies (X and K_u bands, 8-18 GHz) is prepared. The electromagnetic wave shielding film is fabricated using the excellent transmittance, electrical conductivity, and thermal stability of indium tin oxide (ITO), a representative transparent conductive oxide. The inherent mechanical brittleness of oxide ceramics is overcome by adopting a nanobranched structure. In addition, mechanical stability is maintained even after repeated bending experiments (200 000 times). The produced transparent and flexible shielding film is applied to practical GHz devices (Wi-Fi and LTE devices), and signal sensitivity is confirmed to decrease. Therefore, it can be widely applied to various transparent and flexible electronic devices.

Electromagnetic interference shielding effectiveness of polypyrrole-silver nanocomposite films on silane-modified flexible sheet

The conventional electromagnetic interference (EMI) shielding materials are being gradually replaced by a new generation of supported conducting polymer composites (CPC) films due to their many advantages. This work presents a contribution on the effects of silane surface–modified flexible polypyrrole-silver nanocomposite films on the electromagnetic interference shielding effectiveness (EMI-SE). Thus, the UV-polymerization was used to in-situ deposit the PPy-Ag on the biaxial oriented polyethylene terephthalate (BOPET) flexible substrates whose surfaces were treated by 3-aminopropyltrimethoxysilane (APTMS). X-ray Photoelectron Spectroscopy (XPS) analyzes confirmed the APTMS grafting procedure. Structural, morphological, thermal, and electrical characteristics of the prepared films were correlated to the effect of substrate surface treatment. Thereafter, EMI-SE measurements of the elaborated films were carried out as per ASTM D4935 standard for a wide frequency band extending from 50 MHz to 18 GHz. The obtained results confirmed that the APTMS-treated BOPET film exhibit higher EMI shielding performance and better electrical characteristics compared to the untreated film. In fact, a 32% enhancement of EMI-SE was noted for the treated films compared to the untreated ones. Overall, these results put forward the role played by the surface treatment in strengthening the position of flexible PPy-Ag supported films as high-performance materials in electronic devices and electromagnetic interference shielding applications.

Cellulose-Silver Composites Materials: Preparation and Applications

Cellulose has received great attention owing to its distinctive structural features, exciting physico-chemical properties, and varied applications. The combination of cellulose and silver nanoparticles currently allows to fabricate different promising functional nanocomposites with unique properties. The current work offers a wide and accurate overview of the preparation methods of cellulose-silver nanocomposite materials, also providing a punctual discussion of their potential applications in different fields (i.e., wound dressing, high-performance textiles, electronics, catalysis, sensing, antimicrobial filtering, and packaging). In particular, different preparation methods of cellulose/silver nanocomposites based on in situ thermal reduction, blending and dip-coating, or additive manufacturing techniques were thoroughly described. Hence, the correlations among the structure and physico-chemical properties in cellulose/silver nanocomposites were investigated in order to better control the final properties of the nanocomposites and analyze the key points and limitations of the current manufacturing approaches.

Highly efficient patterning technique for silver nanowire electrodes by electrospray deposition and its application to self-powered triboelectric tactile sensor

A patterned transparent electrode is a crucial component of state-of-the-art wearable devices and optoelectronic devices. However, most of the patterning methods using silver nanowires (AgNWs), which is one of the outstanding candidate materials for the transparent electrode, wasted a large amount of unused AgNWs during the patterning process. Here, we report a highly efficient patterning of AgNWs using electrospray deposition with grounded electrolyte solution (EDGE). During electrospray deposition, a patterned electrolyte solution collector attracted AgNWs by strong electrostatic attraction and selectively deposited them only on the patterned collector, minimizing AgNW deposited elsewhere. The enhanced patterning efficiency was verified through a comparison between the EDGE and conventional process by numerical simulation and experimental validation. As a result, despite the same electrospray deposition conditions for both cases except for the existence of the electrolyte solution collector, the coverage ratio of AgNWs fabricated by the EDGE process was at least six times higher than that of AgNWs produced by the conventional process. Furthermore, the EDGE process provided high design flexibility in terms of not only the material of the substrate, including a polymer and a ceramic but also the shape of the substrate, including a 2D flat and 3D curved surface. As an application of the EDGE process, a self-powered touch sensor exploiting the triboelectric effect was demonstrated. Thus, the EDGE process would be utilized in further application in wearable or implantable devices in the field of biomedicine, intelligent robots, and human-machine interface.

A reusable wet-transfer printing technique for manufacturing of flexible silver nanowire film-based electrodes

To explore a simple and efficient way to fabricate thin film electrodes on flexible substrates is highly desired because of its high promising application in optoelectronics. Transfer printing technique plays a key role in the fabrication of flexible electrodes from conventional substrates to flexible substrates. Unfortunately, a simple, room temperature, environmental-friendly and reusable transfer printing technique still remains challenging. Here we demonstrated a novel water-based wet-transfer printing technique that is simple, room temperature, environmental-friendly and reusable by taking advantage of the adjustment of the intermolecular hydrogen bonding between thin film and substrates. This effective and practical transfer technique may provide an effective route to develop electronic flexible devices with high performance.

Flexible Sandwich-Structured Electromagnetic Interference Shielding Nanocomposite Films with Excellent Thermal Conductivities

With the rapid development and popularization of smart, portable, and wearable flexible electronic devices, urgent demands have been raised for flexible electromagnetic interference (EMI) shielding films to solve related electromagnetic pollution problems. With polyvinyl alcohol (PVA) as polymer matrix, the sandwich-structured EMI shielding nanocomposite films are prepared via electrospinning-laying-hot pressing technology, where Fe₃ O₄ /PVA composite electrospun nanofibers in the top and bottom layers and Ti₃ C₂ T_x /PVA composite electrospun nanofibers in the middle layer. Owing to the electrospinning process and the successful construction of the sandwich structure, when the amounts of Ti₃ C₂ T_x and Fe₃ O₄ are respectively only 13.3 and 26.7 wt%, the EMI shielding effectiveness (EMI SE) of the sandwich-structured EMI shielding nanocomposite films reach 40 dB with the thickness of 75 µm, higher than that of (Fe₃ O₄ /Ti₃ C₂ T_x )/PVA EMI shielding nanocomposite films (21 dB) prepared based on blending-electrospinning-hot pressing process under the same amounts of fillers. Furthermore, the prepared sandwich-structured EMI shielding nanocomposite films possess excellent thermal conductivities and mechanical properties. This novel kind of flexible sandwich-structured EMI shielding nanocomposite films with excellent EMI shielding performances, thermal conductivities, and mechanical properties presents broad application prospects in the fields of EMI shielding and protection for high-power, portable, and wearable flexible electronic devices.

Self-assembly in biobased nanocomposites for multifunctionality and improved performance

Concerns of petroleum dependence and environmental pollution prompt an urgent need for new sustainable approaches in developing polymeric products. Biobased polymers provide a potential solution, and biobased nanocomposites further enhance the performance and functionality of biobased polymers. Here we summarize the unique challenges and review recent progress in this field with an emphasis on self-assembly of inorganic nanoparticles. The conventional wisdom is to fully disperse nanoparticles in the polymer matrix to optimize the performance. However, self-assembly of the nanoparticles into clusters, networks, and layered structures provides an opportunity to address performance challenges and create new functionality in biobased polymers. We introduce basic assembly principles through both blending and in situ synthesis, and identify key technologies that benefit from the nanoparticle assembly in the polymer matrix. The fundamental forces and biobased polymer conformations are discussed in detail to correlate the nanoscale interactions and morphology with the macroscale properties. Different types of nanoparticles, their assembly structures and corresponding applications are surveyed. Through this review we hope to inspire the community to consider utilizing self-assembly to elevate functionality and performance of biobased materials. Development in this area sets the foundation for a new era of designing sustainable polymers in many applications including packaging, construction chemicals, adhesives, foams, coatings, personal care products, and advanced manufacturing.

Multifunctional Cellulose Nanopaper with Superior Water-Resistant, Conductive, and Antibacterial Properties Functionalized with Chitosan and Polypyrrole

Cellulose nanopaper (CNP) has been considered as a promising material with great application potential in diverse fields. However, the hydrophilic nature of CNP significantly limits its practical application. In order to improve its water resistance, we demonstrate a facile approach to functionalize CNP by impregnating it with chitosan (CS), followed by in situ polymerization of polypyrrole (PPy). The results indicate that the obtained CNP/CS/PPy shows excellent water resistance with the wet tensile strength of up to 80 MPa, which is more than 10 times higher than that of the pure CNP. Intriguingly, new features (e.g., electrical conductivity, antibacterial activity, and so forth) are achieved at the same time. The functionalized CNP/CS/PPy shows a high conductivity of 6.5 S cm^-1, which can be used for electromagnetic interference shielding applications with a high shielding performance of around 18 dB. In addition, the CNP/CS/PPy exhibits good antibacterial activity toward Staphylococcus aureus and Escherichia coli, with the bacterial reductions of 99.28 and 95.59%, respectively. Thus, this work provides a simple and versatile approach to functionalize CNP for achieving multifunctional properties.

Robust, flexible, and high-performance electromagnetic interference shielding films with long-lasting service

It is of great significance for electromagnetic interference (EMI) shielding materials to fulfill long-lasting service requirements. Here, waterborne polyurethane (WPU) was coated on the surface of a silver nanowire (AgNW) network with sputter-deposited nickel nanoparticles (NiNPs) by dip-coating technology to improve their durability. After five dip-coating cycles, a WPU layer nearly coated the whole surface of the hybrid papers, and only a fraction of the metal filler is bare. The resultant hybrid papers exhibit an electrical conductivity of ∼3500 S m⁻¹, remnant magnetization of 0.03 emu g⁻¹, saturation magnetization of 0.10 emu g⁻¹, and coercivity of 256 Oe. On the one hand, the presence of the WPU coating does not affect the shielding effectiveness (SE) of the hybrid papers; on the other hand, the WPU coating enhances the ability to resist tape peeling. Moreover, the resultant hybrid papers still maintain the original SE value (∼80 dB), even after exposure to air for 5 months owing to the isolation effect of the WPU coating, implying long-lasting durability. The results confirm that the obtained hybrid papers can meet the requirements of practical applications.

It is of great significance for electromagnetic interference (EMI) shielding materials to fulfill long-lasting service requirements.

Polyvinylpyrrolidone Assisted Preparation of Highly Conductive, Antioxidation, and Durable Nanofiber Composite with an Extremely High Electromagnetic Interference Shielding Effectiveness

With booming development of electronics, electromagnetic interference (EMI) shielding materials based on conductive polymer composites (CPCs) have received increasing attention. However, it remains challenging to develop flexible and lightweight CPCs with excellent stretchability, breathability, durability, and high EMI shielding effectiveness (EMI SE). Here, we propose a facile polyvinylpyrrolidone (PVP) assisted preparation of highly electrically conductive and durable nanofiber composites for high performance EMI shielding. The PVP layer could not only greatly enhance the interfacial interaction between the Ag nanoparticles (AgNPs) and hence the mechanical properties (both tensile strength, Young's modulus and elongation at break) of the polymer nanofiber membrane but also forms a protection layer preventing the AgNPs from oxidizing. The electrical conductivity of the nanofiber composite can reach up to 245.7 ± 30.6 S/cm, which is, to a large degree, maintained after cyclic stretching, abrasion, and ultrasonic washing. In addition, the nanofiber composite exhibits excellent breathability, antibacterial, and Joule heating performance. When used as the EMI shielding material, the nanofiber composite shows an extremely high SE and SSE of ∼96.9 dB and 169.7 dB cm³/g, respectively, and EMI shielding performance possesses outstanding stability and durability. This multifunctional nanofibrous composite membrane exhibits promising applications in wearable electronics.

Superhydrophobic and Flexible Silver Nanowire-Coated Cellulose Filter Papers with Sputter-Deposited Nickel Nanoparticles for Ultrahigh Electromagnetic Interference Shielding

Superhydrophobic, flexible, and ultrahigh-performance electromagnetic interference (EMI) shielding papers are of paramount importance to safety and long-term service under external mechanical deformations or other harsh service environments because they fulfill the growing demand for multipurpose materials. Herein, we fabricated multifunctional papers by incorporating sputter-deposited nickel nanoparticles (NiNPs) and a fluorine-containing coating onto cellulose filter papers coated with silver nanowires (AgNWs). AgNW networks with sputter-deposited NiNPs provide outstanding magnetic properties, electrical conductivity, and EMI shielding performance. At an AgNW content of 0.109 vol % and a NiNP content of 0.013 mg/cm², the resultant papers exhibit a superior EMI shielding effectiveness (SE) of 88.4 dB. Additionally, the fluorine-containing coating endows the resultant papers with a high contact angle of 149.7°. Remarkably, the obtained papers still maintain a high EMI SE even after 1500 bending cycles or immersion in water, salt, or strong alkaline solutions for 2 h, indicating their outstanding mechanical robustness and chemical durability. This work opens a new window for designing and implementing ultrahigh-performance EMI shielding materials.

Hybrid structure of MWCNT/ferrite and GO incorporated composites for microwave shielding properties and their practical applications

To eliminate the increasing adverse effects of electromagnetic pollution in everyday life, the shielding abilities of ferrite nanoparticles, multiwalled carbon nanotubes, and graphene oxide based hybrid composites have been investigated. The conceivable applications of the best investigated shielding composite samples on wearable and construction materials were investigated. Zinc substituted nickel and cobalt ferrite nanoparticles were synthesized using a sol–gel method with average crystallite size of 15–20 nm and incorporated with MWCNT and MWCNT–GO in a 1 : 1 weight ratio. Detailed investigations have been done on the prepared nano-composites by using X-ray diffraction, scanning and transmission electron microscopy, Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis, magnetic hysteresis loops, and vector network analysis. The microwave shielding capacity of the multiwalled carbon nanotube-zinc doped cobalt ferrite–graphene oxide hybrid composite was significantly enhanced up to 81.6 dB for the thickness of 2.4 mm in the X-band frequency region. Such a high SE indicates attenuation of the entire incoming EM radiation, which corroborates the potential of these materials in terms of high efficiency, tuneable, stable, and lightweight shielding applications. The synthesized MWCNT–CZFO–GO nanocomposite was used as an absorbent and was incorporated with cotton fabric, camouflage fabric, cement, and gypsum for high-efficiency daily life radiation shielding applications. These incorporated shielding samples (52.3 dB for cement, 31.4 dB for gypsum, 40.8 dB for camouflage fabric, and 28.6 dB for cotton fabric) showed a high attenuation capacity with more than 99.999% attenuation of the incident EM radiation establishing a promising behaviour to neutralize the harmful effects of radiation in day-to-day life.

To eliminate the increasing adverse effects of electromagnetic pollution in everyday life, the shielding abilities of ferrite nanoparticles, multiwalled carbon nanotubes, and graphene oxide based hybrid composites have been investigated.

Preparation of Flexible Carbon Fiber Fabrics with Adjustable Surface Wettability for High-Efficiency Electromagnetic Interference Shielding

In the 5G era, for portable electronics to operate at high performance and low power levels, the incorporation of superior electromagnetic interference (EMI) shielding materials within the packages is of critical importance. A desirable wearable EMI shielding material is one that is lightweight, structurally flexible, air-permeable, and able to self-clean. To this end, a bioinspired electroless silver plating strategy and a one-step electrodeposition method are utilized to prepare an EMI shielding fabric (CEF-NF/PDA/Ag/50-30) that possesses these desirable properties. Porous CEF-NF mats with a spatially distributed silver coating create efficient pathways for electron movement and enable a remarkable conductivity of 370 S mm^-1. When tested within a frequency range of 8.2-12.4 GHz, this highly conductive fabric not only achieves an EMI shielding effectiveness (EMI SE of 101.27 dB at 5028 dB cm² g^-1) comparable to a very thin and light metal but also retains the unique properties of fabrics-being light, structurally flexible, and breathable. In addition, it exhibits a high contact angle (CA) of 156.4° with reversible surface wettability. After having been subjected to 1000 cycles of bending, the performance of the fabric only decreases minimally. This strategy potentially provides a novel way to design and manufacture an easily integrated EMI shielding fabric for flexible wearable devices.

EMI Shielding of the Hydrophobic, Flexible, Lightweight Carbonless Nano-Plate Composites

The cost-effective spray coated composite was successfully synthesis and characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and X-ray diffraction techniques. The one step synthetic strategy was used for the synthesis of nanoplates that have a crystalline nature. The composites are amorphous and hydrophobic with micron thickness (<400 m). The maximum contact angle showed by composite is 132.65° and have wetting energy of -49.32 mN m-1, spreading coefficient -122.12 mN m-1, and work of adhesion 23.48 mN m-1. The minimum thickness of synthesized nanoplate is 3 nm while the maximum sheet resistance, resistivity, and electrical conductivity of the composites are 11.890 ohm sq-1, 0.4399 Ω.cm-1, and 8.967 S.cm-1, respectively. The cobalt nanoplate coated non-woven carbon fabric (CoFC) possesses excellent sheet resistance, hydrophobic nature, and EMI shielding efficiency of 99.99964%. The composite can block above 99.9913% of incident radiation (X band). Hence, the composite can be utilized in application areas such as medical clothes, mobile phones, automobiles, aerospace, and military equipment.

Fabrication of 3D printed antimicrobial polycaprolactone scaffolds for tissue engineering applications

Synthetic polymers are widely employed for bone tissue engineering due to their tunable physical properties and biocompatibility. Inherently, most of these polymers display poor antimicrobial properties. Infection at the site of implantation is a major cause for failure or delay in bone healing process and the development of antimicrobial polymers is highly desired. In this study, silver nanoparticles (AgNps) were synthesized in polycaprolactone (PCL) solution by in-situ reduction and further extruded into PCL/AgNps filaments. Customized 3D structures were fabricated using the PCL/AgNps filaments through 3D printing technique. As demonstrated by scanning electron microscopy, the 3D printed scaffolds exhibited interconnected porous structures. Furthermore, X-ray photoelectron spectroscopy analysis revealed the reduction of silver ions. Transmission electron microscopy along with energy-dispersive X-ray spectroscopy analysis confirmed the formation of silver nanoparticles throughout the PCL matrix. In vitro enzymatic degradation studies showed that the PCL/AgNps scaffolds displayed 80% degradation in 20 days. The scaffolds were cytocompatible, as assessed using hFOB cells and their antibacterial activity was demonstrated on Escherichia coli. Due to their interconnected porous structure, mechanical and antibacterial properties, these cytocompatible multifunctional 3D printed PCL/AgNps scaffolds appear highly suitable for bone tissue engineering.

Polymer-Assisted Fabrication of Silver Nanowire Cellular Monoliths: Toward Hydrophobic and Ultraflexible High-Performance Electromagnetic Interference Shielding Materials

Metal nanofibers with excellent electrical conductivity and superior mechanical flexibility have great potentials for fabrication of lightweight, flexible, and high-performance electromagnetic interference (EMI) shielding architectures. The weak interactions and large contact resistance among the wires, however, hinder their assembly into robust and high-performance EMI shielding monoliths. In this work, we used low fractions of polymers to assist the construction of lightweight, flexible, and highly conductive silver nanowire (AgNW) cellular monoliths with significantly enhanced mechanical strength and EMI shielding effectiveness (SE). The normalized surface specific SE of our AgNW-based cellular monoliths can reach up to 20522 dB·cm²/g, outracing that of most shielding materials ever reported. Moreover, this robust conductive framework enabled the successful fabrication of hydrophobic, ultraflexible, and highly stretchable aerogel/polymer composites with outstanding EMI SE even at an extremely low AgNW content. Thus, this work demonstrated a facile and efficient strategy for assembling metal nanofiber-based functional high-performance EMI shielding architectures.

Wood-Inspired Anisotropic Cellulose Nanofibril Composite Sponges for Multifunctional Applications

Nanocellulose-based porous materials have been recently considered as ideal candidates in various applications. However, challenges on performances remain owing to the disorderly structure and the limited transport specificity. Herein, wood-inspired composite sponges consisting of cellulose nanofibrils (CNFs) and high-aspect-ratio silver nanowires (AgNWs) were generated with anisotropic properties by the directional freeze-drying. The obtained composite sponges exhibited attractive features, such as an excellent compressive stress of 24.5 kPa, low percolation threshold of 0.1 vol % AgNWs, and high electrical conductivity of 1.52 S/cm. Furthermore, the self-assembled ordered structure in the longitudinal direction and synergistic effect between CNFs and AgNWs benefited the sponge interesting anisotropic electrical conductivity, thermal diffusivity, ultrafast electrically induced heating (<5 s), sensitive pressure sensing (errors <0.26%), and electromagnetic interference (EMI) shielding for special practical demands. This multifunctional material inspired by natural woods is expected to broaden new applications as electronic devices for an intelligent switch or EMI shielding.

Highly Electroconductive Nanopapers Based on Nanocellulose and Copper Nanowires: A New Generation of Flexible and Sustainable Electrical Materials

Nowadays, the development of sustainable high-performance functional nanomaterials is in the spotlight. In this work, we report the preparation of a new generation of flexible and high electroconductive nanopapers based on nanofibrillated cellulose (NFC) and copper nanowires (CuNWs). Homogeneous red brick color nanopapers (thickness 30.2-36.4 μm) were obtained by mixing different amounts of NFC aqueous suspensions and CuNWs (1, 5, 10, 20, and 50 wt %), followed by vacuum filtration and drying. scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) analysis confirmed the incorporation of the different amounts of CuNWs, and their uniform and random distribution. All of the nanomaterials displayed good mechanical properties, viz., Young's modulus = 2.62-4.72 GPa, tensile strength = 30.2-70.6 MPa, and elongation at break = 2.3-4.1% for the nanopapers with 50 and 1 wt % of CuNWs mass fraction, respectively. The electrical conductivity of these materials strongly depends on the CuNW content, attaining a value of 5.43 × 10⁴ S·m^-1 for the nanopaper with a higher mass fraction. This is one of the highest values reported so far for nanocellulose-based conductive materials. Therefore, these nanopapers can be seen as an excellent inexpensive and green alternative to the current electroconductive materials for applications in electronic devices, energy storage, or sensors.

A Coral Reef-like Structure Fabricated on Cellulose Paper for Simultaneous Oil-Water Separation and Electromagnetic Shielding Protection

The functional design of paper-based material surfaces with renewable functions and environmentally friendly properties is prevalent nowadays. Herein, a superhydrophobic surface with a coral reef-like structure was prepared on filter paper by electroless copper plating, rapid silver nitrate etching, and facile 1-hexadecanethiol impregnation. After low-surface-energy thiol treatment, this unique coral reef-like structure surface showed excellent superhydrophobicity with a water contact angle of 163.8° and superoleophobicity with an oil contact angle of 0°, which could be used for oil-water separation and had a separation efficiency above 89.17% after 12 consecutive oil-water separations. Because the copper layer and silver nanostructure are both excellent conductive materials, the modified paper exhibited excellent electromagnetic shielding properties, and the electromagnetic interface shielding effectiveness exceeded 63 dB from 9 kHz to 1.5 GHz. The modified paper also had excellent self-cleaning properties and a better corrosion resistance. The unique three-dimensional interweaving structure between the cellulose fibers in the filter paper is fully utilized, and the substitution reaction between the silver ion and the copper coating produces a coral reef-like structure, which provides a new strategy for promoting the wide application of paper-based materials.

Ultra-fast heat dissipating aerogels derived from polyaniline anchored cellulose nanofibers as sustainable microwave absorbers

Electromagnetic (EM) pollution is ubiquitous and has soared to a great extent in the past few decades. The use of plant sourced cellulose nanofibers to fabricate sustainable and high performance electromagnetic shielding materials is foreseen as a green solution by the electronics industry to address this unseen pollutant. In this view, we report a facile and environmentally benign strategy to synthesize ultra-light and highly conductive aerogels derived from cellulose nanofibers (CNF) decorated with polyaniline (PANI) via a simple in-situ polymerization and subsequent freeze drying process devoid of any volatile organic solvents. The obtained conductive aerogels exhibited density as low as 0.01925 g/cc with a maximum EMI shielding value -32 dB in X band region. These porous shields demonstrated strong microwave absorption behavior (95 %) with minimal reflection (5 %) coupled with high specific EMI SE value ∼1667 dB.cm³. g^-1 which make these aerogels a potential candidate for use in telecommunication, military and defense applications.

Multi-layer silver nanowire/polyethylene terephthalate mesh structure for highly efficient transparent electromagnetic interference shielding

Electromagnetic interference protection in optoelectronic devices is challenging because of the dual requirements of optical transmittance and high shielding effectiveness (SE). Herein, we propose a novel silver nanowire (AgNW)/polyethylene terephthalate (PET) multi-layer mesh pattern structure for transparent electromagnetic shielding obtained via laser marking and transfer printing. A three-layer composite shielding film with an optical transmittance of 67.8% exhibits a SE of 44 dB at 10 GHz, which is superior to most of the reported transparent shielding films composed of AgNWs to date. The newly designed multi-layer composite structure can enhance the transparent shielding properties of the shielding film via optimization of the AgNW distribution and the shielding film structure. It is expected that this multi-layer mesh composite structure will have splendid application prospects in electromagnetic shielding films, which require both light transmittance and high SE.

Flexible and Ultrathin Waterproof Cellular Membranes Based on High-Conjunction Metal-Wrapped Polymer Nanofibers for Electromagnetic Interference Shielding

Ultrathin, lightweight, and flexible electromagnetic interference (EMI) shielding materials are urgently demanded to address EM radiation pollution. Efficient design to utilize the shields' microstructures is crucial yet remains highly challenging for maximum EMI shielding effectiveness (SE) while minimizing material consumption. Herein, novel cellular membranes are designed based on a facile polydopamine-assisted metal (copper or silver) deposition on electrospun polymer nanofibers. The membranes can efficiently exploit the high-conjunction cellular structures of metal and polymer nanofibers, and their interactions for excellent electrical conductivity, mechanical flexibility, and ultrahigh EMI shielding performance. EMI SE reaches more than 53 dB in an ultra-broadband frequency range at a membrane thickness of merely 2.5 µm and a density of 1.6 g cm^-3 , and an SE of 44.7 dB is accomplished at the lowest thickness of 1.2 µm. The normalized specific SE is up to 232 860 dB cm² g^-1 , significantly surpassing that of other shielding materials ever reported. More, integrated functionalities are discovered in the membrane, such as antibacterial, waterproof properties, excellent air permeability, high resistance to mechanical deformations and low-voltage uniform heating performance, offering strong potential for applications in aerospace and portable and wearable smart electronics.

A Multifunctional Smart Textile Derived from Merino Wool/Nylon Polymer Nanocomposites as Next Generation Microwave Absorber and Soft Touch Sensor

In recent times e-textiles have emerged as wonder safeguards due to the great potential background in space, military, healthcare, or portable electronics. As a result, widespread research and development have been done to make significant advancement in this field, but it still remains a key challenge to use one single product with multifunctional attributes with the past performance of key characteristics. In this work, phase-separated PEDOT:PSS ornamented with reduced graphene oxide (rGO) nanosheets, deposited on the newly fabricated ultralightweight, superhydrophobic, and mechanically enriched merino wool/nylon (W-N) composite textile followed by the dipping and drying strategy. The open edges-layered structure of rGO helping uniform deposition of PEDOTs clusters, which allows the formation of a stacked layer of PEDOTs/rGO-PEDOTs/PEDOTs for robust three-dimensional electrical transforming channel network within the W-N textile surface. These dip-coated multifunctional textiles show high electrical conductivities up to 90.5 S cm^-1 conjugated with a flexible electromagnetic interference shielding efficiency of 73.8 dB (in X-band) and in-plane thermal conductivity of 0.81 W/mK with a minimum thickness of 0.84 mm. This thin coating maintained the hydrophobicity (water contact angle of ∼150°) leading to an excellent EM protective cloth combined with real-life antenna performance under high mechanical or chemical tolerance. Interestingly, this multiuse textile can also act as an exceptional TASER Proof Textile (TPT) due to a short out of the electrical shock coming from the TASER by its unique conducting network architecture. Remarkably, this coated textile can get a response by the soft touch to lighten up the household bulb and could establish wireless communication via an HC-05 Bluetooth module as a textile-based touch switch. This developed fabric could perform as a new potentially scalable single product in intelligent smart garments, portable next-generation electronics, and the growing threat of EM pollution.

Ultralight, Flexible, and Biomimetic Nanocellulose/Silver Nanowire Aerogels for Electromagnetic Interference Shielding

Ultralight and highly flexible biopolymer aerogels, composed of biomimetic cellular microstructures formed from cellulose nanofibers and silver nanowires, are assembled via a convenient and facile freeze-casting method. The lamellar, honeycomb-like, and random porous scaffolds are successfully achieved by adjusting freezing approaches to modulate the relationships between microstructures and macroscopic mechanical and electromagnetic interference (EMI) shielding performances. Combining the shielding transformation arising from in situ compression and the controlled content of building units, the optimized lamellar porous biopolymer aerogels can show a very high EMI shielding effectiveness (SE), which exceeds 70 or 40 dB in the X-band while the density is merely 6.2 or 1.7 mg/cm³, respectively. The corresponding normalized surface specific SE (defined as the SE divided by the material density and thickness) is up to 178235 dB·cm²/g, far surpassing that of the so-far reported shielding materials. Antibacterial properties and hydrophobicity are also demonstrated extending the versatility and application potential of the biopolymer hybrid aerogels.

Flexible PEBAX/graphene electromagnetic shielding composite films with a negative pressure effect of resistance for pressure sensors applications

In the current work, we fabricated flexible poly(ether-block-amide) (PEBAX)/graphene composite films by a combination of facile melt blending and compression molding technique. The graphene content significantly affects the mechanical properties, electrical conductivity and electromagnetic interference (EMI) shielding performance. An electrically conductive percolation threshold of 1.75 vol% graphene was obtained in the PEBAX/graphene composites. With the introduction of 4.45 vol%, and 8.91 vol% graphene content, the average EMI SE of composite films could reach 16.6 and 30.7 dB, respectively. More interestingly, the PEBAX/graphene composite exhibited a nearly-linear negative pressure coefficient (NPC) effect of resistance with increasing outer pressure stimulation, which was attributed to the formation of more conductive pathways caused by the decreased distance between adjacent graphene. In addition, these composites demonstrated good sensing stability, recoverability and reproducibility after stabilization by cyclic pressure loading. The current study provides guidelines for the large-scale preparation of elastomer NPC sensors and smart EMI shielding devices.

Graphene/PEBAX composite films present high-efficiency EMI shielding properties and good sensitivity as well as sensing stability.