A brief review on electrospun polymer derived carbon fibers for EMI shielding applications

Off/on switchable smart electromagnetic interference shielding aerogel

In this work, composite electrospun fibers containing innovative bioactive glass nanoparticles were produced and characterized. Poly(ε-caprolactone), benign solvents, and sol-gel B- and Cu-doped bioactive glass powders were used to fabricate fibrous scaffolds. The retention of bioactive glass nanoparticles in the polymer matrix, the electrospinnability of this novel solution and the obtained electrospun composites were extensively characterized. As a result, composite electrospun fibers characterized by biocompatibility, bioactivity, and exhibiting overall properties adequate for both hard and soft tissue engineering applications, have been produced. The addition of these bioactive glass nanoparticles was, indeed, able to impart bioactive properties to the fibers. Cell culture studies show promising results, demonstrating proliferation and growth of cells on the composite fibers. Wettability, degradation rate, and mechanical performance were also tested and are in line with previous results.

Binder-free anodes composed of electrospun carbon fibers were prepared for lithium-ion batteries. Nickel−cobalt binary hydroxide (Ni−Co(OH)2) was coprecipitated on the electrospun carbon fibers to form a hierarchical structure with Ni−Co(OH)2 nanoflakes vertically attached on the fiber surface. When the composite fibers were annealed in air, Ni−Co(OH)2 nanoflakes were converted to NiCo2O4 nanosheets at 300°C. Further increasing the annealing temperature to 400°C resulted in the aggregation of NiCo2O4 on the fiber surface, causing the loss of NiCo2O4 nanostructures. When used as anodes, the composite fibers exhibited the higher specific capacity than the pristine carbon fibers. This was attributed to the hierarchical structure of the composite fibers in which the high surface area and rich mesopores of Ni−Co compounds provided easily accessible ion transport across electrolyte/electrode interfaces and additional lithium storage, respectively. Additionally, Ni−Co compounds possessed the high theoretical capacities. By contrast, the interconnected carbon fibers served as a conductive path for charge transfer. They also acted as a buffer to alleviate the Ni−Co-compound volume expansion and contraction during discharging and charging. Among all the samples, the composite fibers annealed at 300°C exhibited the highest capacity of 734 mAh g−1 at a current density of 150 mA g−1.

Double layered design for electromagnetic interference shielding with ultra-low reflection features: PDMS including carbon fibre on top and graphene on bottom

Functionalized magnetic iron oxide/polyacrylonitrile composite electrospun fibers as effective chromium (VI) adsorbents for water purification

Electrospun carbon fibers embedded with core–shell TiC@TiO[formula omitted] nanostructures and their epoxy composites for potential EMI shielding in the Ku band

Poly(glycerol-sebacate) (PGS) and poly(epsilon caprolactone) (PCL) have been widely investigated for biomedical applications in combination with the electrospinning process. Among others, one advantage of this blend is its suitability to be processed with benign solvents for electrospinning. In this work, the suitability of PGS/PCL polymers for the fabrication of composite fibers incorporating bioactive glass (BG) particles was investigated. Composite electrospun fibers containing silicate or borosilicate glass particles (13-93 and 13-93BS, respectively) were obtained and characterized. Neat PCL and PCL composite electrospun fibers were used as control to investigate the possible effect of the presence of PGS and the influence of the bioactive glass particles. In fact, with the addition of PGS an increase in the average fiber diameter was observed, while in all the composite fibers, the presence of BG particles induced an increase in the fiber diameter distribution, without changing significantly the average fiber diameter. Results confirmed that the blended fibers are hydrophilic, while the addition of BG particles does not affect fiber wettability. Degradation test and acellular bioactivity test highlight the release of the BG particles from all composite fibers, relevant for all applications related to therapeutic ion release, i.e., wound healing. Because of weak interface between the incorporated BG particles and the polymeric fibers, mechanical properties were not improved in the composite fibers. Promising results were obtained from preliminary biological tests for potential use of the developed mats for soft tissue engineering applications.

Deformation processes of ultrahigh porous multiwalled carbon nanotubes/polycarbonate composite fibers prepared by electrospinning

This work involved the preparation of composite fibers from a mixture solution of 8% (w/v) of polyarylonitrile (PAN) containing silver (Ag) particles via a redox reaction and activated carbon (AC) using dimethyl formamide (DMF) as a solvent. The AC content was varied at concentrations of 0, 1, 2, 3, 4, and 5% (w/v). The electrospun composite fibers (ECFs) were prepared by using the electrospinning technique. The surface morphology and content of Ag particles of ECFs were determined by using field emission scanning electron microscopy (FE-SEM) and X-ray fluorescent spectroscopy (XRF) methods, respectively. Moreover, the viscosity and conductivity of spinning solutions were investigated as well. The viscosity of spinning solution increased from 45 to 54 Pa. s with the addition of AC particles from 0 to 4 % w/v and then suddenly dropped to 36 Pa. s at 5 % w/v of AC. The conductivity of spinning solutions decreased from 540 to 139 µS cm-1 when the amount of AC increased from 0 to 5% (w/v). ECFs had rough and porous surfaces with fiber diameters in the range of 200-250 nm. The size of fibers decreased with increasing of bead fibers as the dosage of AC increased.

Synthesis and characterization of tigecycline-loaded sericin/poly(vinyl alcohol) composite fibers via electrospinning as antibacterial wound dressings

Synthesis, characterizations, and biocompatibility evaluation of polycaprolactone–MXene electrospun fibers

Silver electroless plating on aminated graphene oxide-based cotton fabric for electromagnetic interference shielding and bioactivity

Electromagnetic Interference (EMI) shielding materials commonly refers to how effective the material in limiting the passage of electromagnetic radiation into the devices. This undesired interference may cause disturbances to the performance of the any electrical systems. Thus, with effective EMI shielding materials, electromagnetic radiations are blocked with barriers made of conductive materials. In military field, the operation of certain communication equipments such as radar system can be interfered by disturbances due to the electromagnetic radiation emitted by external sources. This paper presents the investigations on non-metal materials which are Polyvinyl Chloride (PVC) and carbon fiber composite as EMI shielding materials in building construction. These shielding materials are placed in the concrete block which casted based on the standard wall building of grade 30. These customized structures are proven to reduce signal penetration significantly in the high frequency range up to 2.4 GHz.

Chapter 6 - Nanocellulose-based composites for EMI shielding applications

With the rapid development of electronic equipment, electromagnetic interference and electromagnetic radiation pollution have become serious problems, because excessive electromagnetic interference will not only affect normal operation of electronic equipment but also do great harm to human health. In general, an ideal material for microwave absorption with the characteristics of high reflection loss (RL) intensity, wide effective absorption band (EAB), thin thickness, and lightweight could effectively consume electromagnetic wave (EMW) energy. Therefore, it is crucial to search for such an ideal microwave absorption material to deal with the electromagnetic radiation pollution. Two-dimensional (2D) carbon/nitride MXene has received more and more attention in recent years, because excellent electrical conductivity and rich surface-functional groups in MXene show positive effects on electromagnetic wave absorption. However, as a non-magnetic material with only dielectric loss, MXene exhibits obvious impedance mismatch, which greatly limits its practical applications. Combining MXene with magnetic materials becomes a hotspot for the exploration of ideal microwave absorption materials. As a typical ferrite, Fe<sub>3</sub>O<sub>4</sub> shows excellent soft magnetic properties such as high saturation magnetization, high chemical stability, and simple preparation. In this paper, the 2D Fe<sub>3</sub>O<sub>4</sub>@Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> composite is successfully prepared by hydrothermal method and simple electrostatic adsorption process. The Fe<sub>3</sub>O<sub>4</sub> nanoparticles are uniformly anchored on the surface of large-sized monolayer Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub>, which effectively reduces the stacking of MXene. By regulating the proportion of magnetic materials, the microwave absorption performance of 2D Fe<sub>3</sub>O<sub>4</sub>@Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> composite is investigated. With the content of Fe<sub>3</sub>O<sub>4</sub> nanoparticles in the 2D Fe<sub>3</sub>O<sub>4</sub>@Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> composite increasing from 4 mg to 8 mg, the microwave absorption performance is enhanced obviously. This is caused by the abundant Fe<sub>3</sub>O<sub>4</sub>/Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> interface, scattering channels, point defect, charge density difference in 2D Fe<sub>3</sub>O<sub>4</sub>@Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> composite, and the optimized impedance matching. The minimum reflection loss (RL<sub>min</sub>) of 2D Fe<sub>3</sub>O<sub>4</sub>@Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> composite reaches –69.31 dB at a frequency of 16.19 GHz, and the effective absorption band (EAB) achieves 3.39 GHz. With the content of Fe<sub>3</sub>O<sub>4</sub> nanoparticles further increasing to 10 mg, the microwave absorption performance shows a decreasing trend. Excessive Fe<sub>3</sub>O<sub>4</sub> nanoparticles in the 2D Fe<sub>3</sub>O<sub>4</sub>@Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> composite lead to the decrease of electrical conductivity and thus the impedance dis-matching and dielectric loss decreasing, which leads the microwave absorption performance to decrease. Radar scattering cross section (RCS) is a physical quantity that evaluates the intensity of the scattered echo energy in the intercepted electromagnetic wave energy. The results of the RCS simulation can be applied to real objects which have been widely utilized in radar wave stealth. Its multi-angle simulation results can be used as an important basis for evaluating the stealth capability of microwave-absorbing material. The RCS simulations show that the average RCS value of 2D Fe<sub>3</sub>O<sub>4</sub>@Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> composite is over –47.92 dBm<sup>2</sup> at an incidence angle of 25°, demonstrating its excellent radar wave absorption performance. This study provides new ideas for improving and practically using two-dimensional and magnetic materials in the microwave absorption field and gives a new path to the subsequent development of microwave-absorbing composites.