Electromagnetic interference shielding properties of PMMA modified-Co0.5Zn0.5Fe2O4 − polyaniline composites

Nanocrystalline CoFe2O4 and Co0.5M0.5Fe2O4 (M = Mn, Ni, and Zn) ferrites were prepared by the solution combustion method using oxalyl dihydrazide as a fuel. These materials were characterized by several physicochemical techniques. X-ray diffraction (XRD) patterns indicate the cubic spinel structure of these ferrites. Field emission scanning electron microscopy (FESEM) images demonstrate the microporous nature of the materials because of the large amount of gas production during their synthesis. High resolution transmission electron microscopy (HRTEM) images show lattice fringes corresponding to the {220} and {311} planes of the spinel structure. Fourier transform infrared (FTIR) spectra exhibit absorption bands around the 500-600 cm-1 wavenumber region which are related to metal-oxygen bonds with tetrahedral coordination. Symmetric and asymmetric stretching and symmetric bending modes associated with tetrahedral and octahedral cations present in the spinel structures have been assessed by Raman spectroscopy. X-ray photoelectron spectroscopy (XPS) studies demonstrate the presence of Co2+, Mn2+, Ni2+, Zn2+, and Fe3+ in tetrahedral and octahedral coordinations in these ferrites. Co0.5Zn0.5Fe2O4 is observed to show the highest saturation magnetization among all these materials. The dielectric measurements reveal that the dielectric constant and loss values decrease with an increase in frequency and the ac conductivity increases at higher frequencies due to mobilization of the charge carriers.

MOF-derived CoNC@rGO/amine-rich@rGO/fluorinated-epoxy nanocomposites with EMI shielding, mechanical robustness, superamphiphobicity and long-term anticorrosion properties

Co-doped polyaniline composites for biological application: Morphological, functional, optical and antibacterial activities

With the increasing pollution of electromagnetic (EM) radiation, it is necessary to develop low-cost, renewable electromagnetic interference (EMI) shielding materials. Herein, wood-derived carbon (WC) materials for EMI shielding are prepared by one-step carbonization of renewable wood. With the increase in carbonization temperature, the conductivity and EMI performance of WC increase gradually. At the same carbonization temperature, the denser WC has better conductivity and higher EMI performance. In addition, due to the layered superimposed conductive channel structure, the WC in the vertical-section shows better EMI shielding performance than that in the cross-section. After excluding the influence of thickness and density, the specific EMI shielding effectiveness (SSE/t) value can be calculated to further optimize tree species. We further discuss the mechanism of the influence of the microstructure of WC on its EMI shielding properties. In addition, the lightweight WC EMI material also has good hydrophobicity and heat insulation properties, as well as good mechanical properties.

Summary: Polyaniline (PANI) composites were prepared with both unmodified and amine modified MWCNTs with and without BaTiO3 through in‐situ oxidative polymerization. Uniform coating of PANI on the MWCNTs and BaTiO3 surfaces was found which was evident from the Field Emission Scanning Electron Microscopic (FESEM) and High Resolution Transmission Electron Microscopic (HRTEM) images. The structure of pure and amine modified MWCNTs was identified by Fourier Transform Infrared Spectroscopy (FTIR). The thermal stability of the amine modified composite with BaTiO3 is higher than that of the unmodified composite because of the better affinity between modified MWCNTs and polymer matrix and due to the higher stability of barium titanate itself. The capacitance of amine modified MWCNTs and BaTiO3 composites was less than that of the pure MWCNTs composites but the thermal stability increased in amine modified MWCNTs and BaTiO3 composites with respect to the pure MWCNTs composites. The maximum capacitance and energy density values were found in MWCNT/PANI composites which were equal to 523.20 F/g and 142.83 Wh/kg respectively at a scan rate of 10mv/s. Maximum power density was found to be 5147.70 W/kg in the same composite at a scan rate of 200 mv/s.

Graphene/carbon fiber network constructed by co-carbonization strategy for functional integrated polyimide composites with enhanced electromagnetic shielding and thermal conductive properties

Silver (Ag)/carbonyl iron particles (CIPs) were prepared by electroless plating successfully to improve the electromagnetic interference (EMI) shielding and antioxidation properties of CIPs. The microstructure, phase composition, thermogravimetric (TG), electromagnetic and EMI shielding properties were analyzed respectively. Experimental results show that Ag particles were uniformly distributed on the surface of CIPs. TG results show the apparent weight gain temperature of Ag/CIPs was deferred compared with the weight gain temperature of CIPs. The total EMI SE value of Ag/CIPs/EP composite reaches about 36 dB with thickness 1.5 mm, which is far superior to the value of CIPs/EP composite. The EMI shielding result shows such Ag/CIPs composite material has an outstanding EMI shielding effect in the measured frequency band (8.2 GHz–12.4 GHz).

Cadmium sulfide nanoflowers (CdS-NF), nanorods (CdS-NR), and its nanocomposites with polyaniline (PANI) were successfully synthesized using facile chemical methods. Transmission electron microscopy (TEM) images confirmed the growth of CdS as nanoflowers and nanorods. High-resolution transmission electron microscopy (HRTEM) images showed clear lattice fringes, indicating good crystallinity of the CdS nanostructures and the formation of interface between PANI and CdS. The photocatalytic activity of CdS nanostructures and its composites was demonstrated for the degradation of methylene blue (MB) dye under visible light irradiation. The PANI/CdS nanocomposites showed enhancement in the photocatalytic activity as compared to bare CdS nanostructures, and it is attributed to efficient charge transfer between CdS and PANI. Photoluminescence study confirmed the enhancement in photogenerated electron–hole pairs separation in CdS nanostructures after the addition of PANI. The composite of PANI with CdS-NF exhibited larger improvement in the photodegradation efficiency over CdS-NF as compared to the improvement observed in PANI/CdS-NR over CdS-NR, which is attributed to the formation of more interfacial sites between PANI and CdS nanoflowers as compared to PANI and CdS nanorods. Our present work indicates that by carefully designing the semiconductor nanomaterial composites, the photocatalytic activity can be significantly enhanced.

A green and sustainable approach to recycle the waste iron rust into a valuable α modification of Fe2O3 via simple grinding and calcination for application in a hybrid supercapacitor is reported. The α-Fe2O3 was coupled with carbon nanofibers (CNFs) and conducting polymer, polyaniline (PANI), to form composite hybrid supercapacitor electrode materials. The conventional hydrothermal, electrospinning, and in-situ polymerization processes were used to prepare composites. Further, X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), scanning electron microscopy (SEM), and energy-dispersive x-ray (EDAX) spectroscopy were used to study the structural, morphological, and compositional properties of the as-synthesized α-Fe2O3 and its composites with CNF and PANI. The α-Fe2O3/CNF and α-Fe2O3/PANI composites, coated on carbon rod, were used as electrodes in a three-electrode system to study electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and galvanostatic charge–discharge (GCD) in 1 M H2SO4. The XRD studies revealed the formulation of iron rust into α-Fe2O3 modifications with an average of 28 nm crystallite size. Uniform dispersion of α-Fe2O3 over CNF of 400–500 nm diameter and excellent covering of PANI over α-Fe2O3 nanomaterials were the morphological features observed for α-Fe2O3 /CNF and α-Fe2O3 /PANI composites, respectively. The electrochemical studies on α-Fe2O3/PANI composites exhibit higher performance as against Fe2O3/CNF with respect to specific capacitance, 192 Fg−1 (88.88 Fg−1); energy density, 11.28 Whkg−1 (3.084 Whkg−1); power density, 162 Wkg−1 (69.39 Wkg−1); and capacitance retention of 80% (75%) after 5000 charge–discharge cycles. The heavy dispersion of α-Fe2O3 over long CNF and PANI fibers with intimate contact resulted in abundant active sites for electrochemical reactions leading to the obtained result. The rust-derived α-Fe2O3 with PANI offers excellent stability to act as a potential candidate for sustainable hybrid supercapacitor application.

Bridge-graphene connecting polymer composite with a distinctive segregated structure for simultaneously improving electromagnetic interference shielding and flame-retardant properties

A facile route was proposed to synthesize polyaniline (PANI) uniformly deposited on bagasse fiber (BF) via a one-step in situ polymerization of aniline in the dispersed system of BF. Correlations between the structural, electrical, and electromagnetic properties were extensively investigated. Scanning electron microscopy images confirm that the PANI was coated dominantly on the BF surface, indicating that the as-prepared BF/PANI composite adopted the natural and inexpensive BF as its core and the PANI as the shell. Fourier transform infrared spectra suggest significant interactions between the BF and PANI shell, and a high degree of doping in the PANI shell was achieved. X-ray diffraction results reveal that the crystallization of the PANI shell was improved. The dielectric behaviors are analyzed with respect to dielectric constant, loss tangent, and Cole-Cole plots. The BF/PANI composite exhibits superior electrical conductivity (2.01 ± 0.29 S·cm-1), which is higher than that of the pristine PANI with 1.35 ± 0.15 S·cm-1. The complex permittivity, electromagnetic interference (EMI), shielding effectiveness (SE) values, and attenuation constants of the BF/PANI composite were larger than those of the pristine PANI. The EMI shielding mechanisms of the composite were experimentally and theoretically analyzed. The absorption-dominated total EMI SE of 28.8 dB at a thickness of 0.4 mm indicates the usefulness of the composite for electromagnetic shielding. Moreover, detailed comparison of electrical and EMI shielding properties with respect to the BF/PANI, dedoped BF/PANI composite, and the pristine PANI indicate that the enhancement of electromagnetic properties for the BF/PANI composite was due to the improved conductivity and the core-shell architecture. Thus, the composite has potential commercial applications for high-performance electromagnetic shielding materials and also could be used as a conductive filler to endow polymers with electromagnetic shielding ability.

SmFeO3@(x)polyaniline composites with porous structure for efficient microwave-absorbing application

Enhanced photocatalytic performance of ZnSe/PANI nanocomposites for degradation of organic and inorganic pollutants

Effects of SiC fibers on microwave absorption and electromagnetic interference shielding properties of SiCf/SiCN composites

Improved dielectric and electromagnetic interference shielding properties of ferrocene-modified polycarbosilane derived SiC/C composite ceramics