Tunable Electromagnetic Interference Research Articles

Carboxylate-Decorated Multiwalled Carbon Nanotube/Aramid Nanofiber Film for Tunable Electromagnetic Interference Shielding Performance and Rapid Electric Heating Capacity

Carboxylate-Decorated Multiwalled Carbon Nanotube/Aramid Nanofiber Film for Tunable Electromagnetic Interference Shielding Performance and Rapid Electric Heating Capacity

Effective fabrication of flexible nickel chains/acrylate composite pressure-sensitive adhesives with layered structure for tunable electromagnetic interference shielding

Effective fabrication of flexible nickel chains/acrylate composite pressure-sensitive adhesives with layered structure for tunable electromagnetic interference shielding

Robust flame-retardant, super mechanical laminate epoxy composites with tunable electromagnetic interference shielding

Considering the high strength, excellent heat resistance, and fast-curing properties of room temperature epoxy (EP), it has been extensively used in positioning, assembly, repair, sealing, potting, and other applications. However, lack of reasonable structural design and precise composition control, it is hard to accomplish 5G communication and resist harsh environments, which are urgently needed for practical applications. Therefore, a smart electromagnetic interference (EMI) device with strong designability has been prepared through a dipping/supplying and hand-laying/vacuum bag pressing, which could not only show excellent shielding effectiveness (SE) but also achieve tunable SE derived from the content of Ti3C2Tx. Meanwhile, thanks to the triangle understanding of composition, structure, and properties, we find a promising flame retardant (ammonium polyphosphate: APP). Our results display that with a V0 rating in the UL-94 test and the LOI value as high as 40% for AEP-RFT1.2, the peak heat release rate (pHRR) and total heat release (THR) of AEP-RFT1.2 are reduced by 77.6% and 51.3%, respectively. Besides, the resultant SE of AEP-RFT1.2 can surpass 30 dB in the X band, which is enough for commercial use. This work provides a facile and efficient strategy to fabricate robust flame retardancy, super mechanical strength, and tunable electromagnetic interference shielding room-temperature cured laminate epoxy composites, which also gives an avenue for industrial applications.

Tunable Electromagnetic Interference Shielding Properties of Binary Thermoplastic Composites Prepared by Reactive Microencapsulation

Tunable Electromagnetic Interference Shielding Properties of Binary Thermoplastic Composites Prepared by Reactive Microencapsulation

Functional Polyaniline/MXene/Cotton Fabrics with Acid/Alkali-Responsive and Tunable Electromagnetic Interference Shielding Performances.

Although two-dimensional transition-metal carbides (MXenes) and intrinsic conductive polymers have been combined to produce functional electromagnetic interference (EMI) shielding composites, acid/alkali-responsive EMI shielding textiles have not been reported. Herein, electrically conductive polyaniline (PANI)/MXene/cotton fabrics (PMCFs) are fabricated by an efficient vacuum filtration-assisted spray-coating method for acid/alkali-responsive and tunable EMI shielding applications on the basis of the high electrical conductivity of MXene sheets and the acid/alkali doping/de-doping feature of PANI nanowires. The as-prepared PMCF exhibits a sensitive ammonia response of 19.6% at an ammonia concentration of 200 ppm. The high EMI shielding efficiency of ∼54 dB is achieved by optimizing the decorated structure of the PANI/MXene coating on the cotton fabrics. More importantly, the PMCF can act adaptively as a "switch" for EMI shielding between the efficient strong shielding of 24 dB and the inefficient weak shielding of 15 dB driven by the stimulation of hydrogen chloride and ammonia vapors. This multifunctional fabric would possess promising applications for intelligent garments, flexible electronic sensors, and smart electromagnetic wave response in special environments.

From materials to components: 3D-printed architected honeycombs toward high-performance and tunable electromagnetic interference shielding

With booming development of 5G communications and electronic devices, electromagnetic waves (EMWs) radiation pollution has aroused much concern on public, and great efforts are being made to develop the high-performance electromagnetic interference shielding (EMI SE) materials. However, inherent deficiencies of traditionally processing technology restrain the current materials to fabricate desirable architectures for SE applications. Herein, taking full advantages of 3D printing in free-construction, architected honeycombs featuring lightweight and high-efficient EMI SE are designed with polylactic acid (PLA) as matrix, and graphene nanosheets and carbon nanotubes hybrids (GNs/CNTs) as functional fillers . The optimal printed material shows a high electrical conductivity up to 110.8 S/m and outstanding EMI SE property of 53.5 dB, far exceeding the standard of commercially shielding materials (20 dB). More encouragingly, this work makes a deep insight into the intrinsic connection of porous structure of 3D-printed components on shielding mechanism, which reveals that as the pore size is far less than a certain proportion of incident wavelength (λ/5), the components exhibit a good reconcilability on the lightweight (0.4–1.0 g/cm 3 ) and high-performance EMI SE (35–45 dB). From fundamental materials to desirable components, this breakthrough lays a solid foundation for the free-construction of diversified architectures in EMI SE applications. • The strong conductive networks are constructed by the hybridization of graphene nanosheets and carbon nanotubes. • The hybrid networks endow the 3D-printed components with superior electromagnetic interference shielding (∼53.5 dB). • The diameter of porous structures should be less than the 1/5 of incident wavelength (λ) to shield electromagnetic waves. • The 3D-printed honeycombs exhibit a good reconcilability on lightweight and electromagnetic interference shielding.

Self-assembled 3D-microstructured dual carbon black filled polymer nanocomposite-coated fabric for tunable electromagnetic interference shielding

Dual carbon black (CB) was used to create self-assembled three-dimensional (3D)-microstructured polymer nanocomposite by a simple solution mixing process. A mechanical stirrer was employed for uniform dispersion and minimizing CB aggregates sizes in the viscous blended medium of hydrolyzed polyvinyl alcohol (PVA) and natural rubber latex (NRL). A stable 3D-microstructural architecture was obtained when an extremely high volume fraction (0.54) of dual CB was used. 3D-microstructured polymer nanocomposite was then applied on the cotton fabric and characterized for the final performance of electromagnetic interference (EMI) shielding effectiveness. The morphological and microstructural analysis revealed that dual CB at a particular ratio of 10:90 (smaller:larger) could provide excellent electrical conductivity (>1.5 S/cm) as well as EMI shielding when assessed against a frequency range of 8.2–12.4 GHz. A durable ultra-thin layer (100 µm) of nanocomposite was sufficient to achieve tunable >31 dB shielding effectiveness.

Ultrathin and Mechanically Robust Mussel Byssus‐Inspired MXene@Aramid Nanofibers Materials with Superior Endurance in Harsh Environments for Tunable EMI Shielding Performance

AbstractReducing the fire hazards caused by high power electromagnetic (EM) waves and maintaining operational status of EM interference (EMI) shielding devices in harsh environments have caught increasing eyesight. In this paper, a series of promising EMI shielding materials with mussel byssus‐inspired structure are accomplished via an efficient vacuum‐assisted filtration approach. The flexible multilayered MXene@ANF nacres reveal superior mechanical property compared with both self‐supporting MXene film and MXene@ANF mixture film. Meanwhile, these nacres exhibit both exceeding and tunable EMI shielding effectiveness (EMI SE) of 40–60 dB in 8.2–12.4 GHz with a thickness of ≈20 µm and the absolute SE (SSEt) accomplishes 36641.94 dB·cm2 g−1. Besides, the exceeding thermal insulation of ANF offers the MXene nacres with an outstanding flame‐stopping capacity, and it can still block 99.99% EM waves after 2 min burning. Furthermore, MXene nacres perform superior endurance in harsh environment and retain EMI SE of 42 dB after the ultralow temperature damage. The EMI SE and fire safety of MXene@ANF with two typical structures, composite films and foam, are also systematically investigated. Therefore, this work is promising to fabricate tunable EMI shielding products with low fire hazards and high endurance in harsh environments.

Ultrahigh and Tunable Electromagnetic Interference Shielding Performance of PVDF Composite Induced by Nano-Micro Cellular Structure.

Lightweight and efficient electromagnetic interference (EMI) shielding materials play a vital role in protecting high-precision electronic devices and human health. Porous PVDF/CNTs/urchin-like Ni composites with different cell sizes from nanoscale to microscale were fabricated through one-step supercritical carbon dioxide (CO2) foaming. The electrical conductivity and electromagnetic interference (EMI) shielding performance of the composites with different cell sizes were examined in detail. The results indicated that the nanoscale cell structure diminishes the EMI shielding performance of the composite, whereas the microscale cell structure with an appropriate size is beneficial for improving the EMI shielding performance. A maximum EMI shielding effectiveness (SE) of 43.4 dB was achieved by the composite foams which is about twice that of the solid composite. Furthermore, as the supercritical CO2 foaming process reduces the density of the composite by 25–50%, the EMI SSE (specific shielding effectiveness)/t(thickness) of the composite reaches 402 dB/(g/cm2), which is the highest value of polymer foam obtained to the best of the authors’ knowledge. Finally, compression tests were performed to show that the composites still maintained excellent mechanical properties after the supercritical CO2 foaming process.

Scalable Production of Bioinspired Mxene/Black Phosphorene Nanocoatings for Hydrophobic and Fire-Safe Textiles with Tunable Electromagnetic Interference and Exceeding Thermal Management

Scalable Production of Bioinspired Mxene/Black Phosphorene Nanocoatings for Hydrophobic and Fire-Safe Textiles with Tunable Electromagnetic Interference and Exceeding Thermal Management

Integrated hierarchical macrostructures of flexible basalt fiber composites with tunable electromagnetic interference (EMI) shielding and rapid electrothermal response

Adjustable and durable EMI shielding fabrics with excellent mechanical performance are urgently required owing to the rapid growing of electronics in industrial, military and aerospace fields. Herein, a highly flexible and durable conductive basalt fabric (BF) composite was firstly fabricated by integrating Ti 3 C 2 T x nanosheets and conformal natural rubber-Ti 3 C 2 T x layer via a facile spray-drying method. The effects of the natural rubber outlayer with or without Ti 3 C 2 T x nanosheets on the composite are examined to determine the optimal composition and structure. The Ti 3 C 2 T x nanosheets form a continuous and compact nacre lamellar coating on the surface of the external BF fibers, resulting in the main EMI shielding function. Especially, the conductive natural rubber-Ti 3 C 2 T x (TNR) outlayer could not only protect the inner Ti 3 C 2 T x coating, but also form conductive connections between conductive BF fibers. The resultant EMI shielding basalt fabrics possess hierarchical macrostructures, which could even obtain an ideal EMI SE value of 41.53 dB. Besides, the TNR outlayer could also fasten the fabric structure and protect the conductive network, which led to negligible decreases after repeatedly bending to 10.0 mm radius for 200 cycles (99.0% retention), sonication for 30 min (98.8% retention) and peeling for 200 cycles (94.4% retention). Moreover, such fabrics also showed outstanding electro-thermal property. Even if applied a low voltage of 4 V, the temperature would immediately reach up to over 70 °C, which also possess excellent cycling stability. Consequently, this work reveals an effective and facial technology for preparing a much more competitive EMI shielding fabric. • EMI shielding basalt fiber composites were developed with hierarchical structure. • Multilayer coating was prepared by the spray-drying technique. • The resultant textile possesses adjustable EMI shielding performance and rapid electrothermal response. • The resultant textile exhibits superior durability under continous external forces.

Polyurethane/polydopamine/graphene auxetic composite foam with high-efficient and tunable electromagnetic interference shielding performance

In this work, two kinds of auxetic composite foams of polyurethane (PU) with polydopamine (PDA) and graphene (GR) (PU/PDA/GR) were prepared by dip-coating and ultrasonic immersing, then followed by triaxial compression-heating process. The electromagnetic interference (EMI) shielding effectiveness (SE) value of the PU/PDA/GR auxetic composite foam with a Poisson's ratio of −2.36 from PU foam with open cellular structure reaches 59.75 dB, which is 8.9 times of the positive Poisson's ratio composite foam with the same GR content. Furthermore, the relationship of the EMI shielding performance of auxetic foam with different forms of reentrant structure was studied for the first time, in which the absolute value of negative Poisson's ratio was used to quantitatively describe the difference of the reentrant structure in the obtained auxetic foam. The larger the absolute value of negative Poisson's ratio is, the better the EMI shielding performance of the composite foam is. The high absorption EMI SE and the existence of reentrant structure are the key factors for the high EMI shielding performance of the auxetic composite foam. In addition, it is found that the EMI SE of the auxetic foam can be adjusted via simple heating treatment, showing that the auxetic composite foam may be used as a temperature-regulated EMI shielding material in the future.

Direct Ink Writing of Highly Conductive MXene Frames for Tunable Electromagnetic Interference Shielding and Electromagnetic Wave-Induced Thermochromism

Highlights3D printing of MXene frames with tunable electromagnetic interference shielding efficiency is demonstrated.Highly conductive MXene frames are reinforced by cross-linking with aluminum ions.Electromagnetic wave is visualized by electromagnetic-thermochromic MXene patterns.The highly integrated and miniaturized next-generation electronic products call for high-performance electromagnetic interference (EMI) shielding materials to assure the normal operation of their closely assembled components. However, the most current techniques are not adequate for the fabrication of shielding materials with programmable structure and controllable shielding efficiency. Herein, we demonstrate the direct ink writing of robust and highly conductive Ti3C2Tx MXene frames with customizable structures by using MXene/AlOOH inks for tunable EMI shielding and electromagnetic wave-induced thermochromism applications. The as-printed frames are reinforced by immersing in AlCl3/HCl solution to remove the electrically insulating AlOOH nanoparticles, as well as cross-link the MXene sheets and fuse the filament interfaces with aluminum ions. After freeze-drying, the resultant robust and porous MXene frames exhibit tunable EMI shielding efficiencies in the range of 25–80 dB with the highest electrical conductivity of 5323 S m−1. Furthermore, an electromagnetic wave-induced thermochromic MXene pattern is assembled by coating and curing with thermochromic polydimethylsiloxane on a printed MXene pattern, and its color can be changed from blue to red under the high-intensity electromagnetic irradiation. This work demonstrates a direct ink printing of customizable EMI frames and patterns for tuning EMI shielding efficiency and visualizing electromagnetic waves.

Investigation on the structural quality dependent electromagnetic interference shielding performance of few-layer and lamellar Nb2CTx MXene nanostructures

Tunable Electromagnetic Interference (EMI) shielding behaviors of 2D MXene (Nb2CTx) were explored via different exfoliation conditions. Stacked, lamellar few-layer, oxygen-related surface functional groups, and structural defects along with oxidative products of Nb2CTx were identified by tuning chemical etching conditions during one-step exfoliation process. Exfoliation of Nb2CTx with a tightly packed stacked structure remarked at lower etching times. The unpacking of Nb2CTx into lamellar morphology followed by separated few-layer Nb2CTx remarked at moderate etching time, whereas structural misalignment, defects, and oxidation of Nb2CTx occurred during prolonged chemical etching times. Synergistic effect of one-step extracted few-layers and lamellar structured Nb2CTx favorably enrich the assembly of multiple electrical conductive pathways responsible for absorption dominated EMI shielding performance in X- and Ku-band region. The assembled wax nanocomposites with 80% of Nb2CTx loading exfoliated at 100 h etching time at a thickness of 1 mm exhibited EMI shielding effectiveness of about 44.09 ± 1.99 dB at 12 GHz, and its EMI attenuation mechanism explained by conduction and eddy current loss. The combined action of few-layer and lamellar Nb2CTx nanostructures could be interesting for making novel shielding materials; open a new avenue for niobium series in the MXene family for elaborated applications.

Magnetic Ti3C2Tx/Fe3O4/Aramid nanofibers composite paper with tunable electromagnetic interference shielding performance

Increasingly popularity of electronic devices and wireless apparatus requires advanced materials to cope with severe electromagnetic wave pollution. Herein, magnetic EM wave shielding material, Ti3C2Tx/Fe3O4/aramid nanofibers composite paper, composed of low-dimensional Ti3C2Tx flakes and carboxylation Fe3O4 nanoparticles, was developed via vacuum-assisted filtration. At the meanwhile, uniform dispersion of components was achieved to overcome magnetic through ingenious electrostatic force regulation originated from negative functional groups. The Ti3C2Tx/Fe3O4/aramid nanofibers composite paper exhibited suitable magnetic performance, outstanding electrical conductivity, and excellent electromagnetic interference shielding performance. Moreover, the Ti3C2Tx/Fe3O4/aramid nanofibers composite paper demonstrated favorable mechanical properties, whose tensile strength and Young’s modulus reached 132.2 ± 2.1 MPa and 5.23 ± 0.14 GPa, respectively. The combination of electromagnetic shielding capacity (derived from Ti3C2Tx flakes, carboxylation Fe3O4 nanoparticles) and mechanical properties (derived from aramid nanofibers) provided feasible strategy in fabricating advanced EMI shielding composite with astonishing comprehensive performance.

Highly stretchable graphene/polydimethylsiloxane composite lattices with tailored structure for strain-tolerant EMI shielding performance

The fast-growing wearable and portable electronics bring imperative demand for high-performance stretchable electromagnetic interference (EMI) shielding materials to tackle the issue of electromagnetic (EM) wave pollution. In this work, highly stretchable and conductive graphene/polydimethylsiloxane lattices are fabricated through a facile 3D printing technique. Benefiting from the unique 3D interconnected and robust conductive network, the resultant composite lattices deliver excellent stretchability of 130%, tunable EMI shielding effectiveness (SE) as high as 45 dB, along with exceptional durability, showing over 90% retention of EMI SE even after 200 cycles of repeated stretching and releasing at strains up to 100%. In addition, the composite lattices exhibit outstanding shielding stability, because the deformation of lattice structure effectively shares the external strain, and the filaments perpendicular to the loading direction act as stabilizing layers preventing the steep resistance changes. The exceptional combination of mechanical properties and EMI shielding performance of the composite lattice provide a brand new perspective for next-generation flexible and stretchable electronics.

Temperature and strain-induced tunable electromagnetic interference shielding in polydimethylsiloxane/multi-walled carbon nanotube composites with temperature-sensitive microspheres

Herein, the elastomer composites with temperature and strain-induced tunable electromagnetic interference (EMI) shielding effectiveness (SE) were successfully obtained by introducing temperature-sensitive microspheres (TSM) into the mixture of polydimethylsiloxane/multi-walled carbon nanotube (PDMS/CNT). The EMI shielding performance of the composites under different temperature and compression strain was evaluated carefully to investigate the mechanism of temperature and strain-induced regulation on EMI shielding. The TSM particles in the PDMS/TSM/CNT composites could be easily adjusted by specific temperature and strain, which resulted in the rearrangement of CNT conductive network and exhibited different electrical conductivity and EMI shielding performance. For temperature-induced regulation, the EMI SE of the composites decreased after being treated at 120 °C and then partly recovered at 150 °C. For strain-induced regulation, the EMI SE of the composites was reduced after being compressed 70%. Furthermore, the strain-induced reduction of the composites could partly recover once heating at 120 °C again.

Strategy for constructing electromagnetic interference shielding and flame retarding synergistic network in poly (butylene succinate) and thermoplastic polyurethane multilayered composites

Fabricating electromagnetic interference (EMI) shielding materials with excellent flame retarding properties is significant to attenuate undesirable electromagnetic waves caused by electronic devices and simultaneously improve the flame safety of the electronic components. Herein, a novel EMI shielding composite with multilayered structure was fabricated at a low particle loading via layer-multiplying coextrusion technology. Especially, within the multilayered composites, poly (butylene succinate) (PBS) filled with carbon nanotubes (CNTs) was used to construct conducting layer while thermoplastic polyurethane (TPU) filled with intumescent flame retardants (IFRs) and CNTs was used to construct synergistic flame-retarding layer. The content of CNTs and IFRs in the whole system were below 4 wt% and 20 wt%, respectively. Morphological observation demonstrated the alternating multilayered structure and the selective distribution of IFRs and CNTs. Besides, by tailoring the layer numbers, the composites showed tunable EMI shielding and flame retarding performances. With regard to EMI shielding performance, the absorption-dominated average EMI shielding effectiveness (SE) values of both 8- and 16-layer specimens exceeded 30 dB in the range of 8.2–12.4 GHz. Furthermore, superior flame retardancy with prompt self-extinguishment and anti-dripping was achieved in these specimens owning to the production of continuous and foaming carbonaceous structure among layers. Especially the 8-layer specimen, the UL-94 rating was categorized in V-0. Consequently, this work provided a promising and facile route to fabricate polymeric composites simultaneously possessing excellent EMI shielding and flame-retarding properties to fulfill the stringent requirements in practical application.

Homogeneous silver nanoparticles decorating 3D carbon nanotube sponges as flexible high-performance electromagnetic shielding composite materials

Nowadays flexible high-performance electromagnetic interference (EMI) shielding materials are greatly demanded in military and daily purpose. To yield high shielding effectiveness (SE), the traditional metallic EMI materials always require a large mass of loading in a composite matrix, which is uneconomic and harmful to the mechanical property of the materials. Herein the homogeneous decoration of Ag nanoparticles on a light-weight and robust carbon nanotube sponge (CNTS) based 3D conductive scaffold is introduced. The flexible Ag/CNTS/PDMS composites exhibit an extremely high and tunable EMI shielding performance with improved mechanical strength and high conductivity. The maximum EMI SE is measured to be even greater than 90 dB in the X-band (8–12 GHz) with a low loading of Ag (3%, wt %) and CNTS (4%, wt %). In addition, the 3D inter-connected pore structure enables EM waves to reflect multiple times inside the Ag/CNTS hybrids which results in a strong absorption ability. The total EMI shielding property can be further conveniently controlled by tuning the Ag-deposition parameters as well as the thickness of the sample. The current approach successfully avoids the dispersion problem of the fillers and will be of great importance in development of high-performance EMI shielding materials.

Mechanically robust ANF/MXene composite films with tunable electromagnetic interference shielding performance

MXene-based materials have been widely studied recently for effective electromagnetic interference (EMI) shielding due to the prominent intrinsic electrical conductivity. Nevertheless, the poor mechanical performance of pure MXene films limits the practical application in EMI shielding. Thus, we integrate MXene with aramid nanofiber (ANF) to develop a composite film with layered structure through a simple vacuum-assisted filtration method. The resulting ANF/MXene (20/80) composite exhibits a high electrical conductivity of 879.0 S/cm, EMI shielding effectiveness (SE) of 40.6 dB and specific SE (SSE/t, SE divided by the density and thickness) of 50,491 dB∙cm2∙g−1 with an ultrathin thickness of 3.2 μm. Furthermore, the ANF/MXene (60/40) realizes a balance between mechanical properties and EMI shielding performance with the strength of 201.3 MPa and SE of 28.1 dB, which enables the ANF/MXene composite films as promising EMI shielding materials with excellent mechanical robustness.