Improved Electromagnetic Interference Shielding Response of Polyaniline Containing Magnetic Nano-ferrites

Improvement of electromagnetic interference (EMI) shielding materials with miniaturization of devices is an important area of research in various applications like communication, electronic warfare, defense, and different civilian applications. Nano-crystalline ferrite, MFe2O4 (M = Ni, Zn, and Co), powders have been synthesized by sol-gel citrate nitrate precursor method. The crystalline size of samples was found in the range of 20-45 nm as analyzed by XRD and TEM analysis. Polyaniline/ferrite nano-composites with 50 wt% were synthesized by mechanical blending. The structural and magnetic properties of the nano-particles were characterized by using Rietveld analysis of powder X-ray diffraction and vibrating sample magnetometer (VSM) respectively. Using the Rietveld refinement, the goodness of fit, interatomic distance, Bragg contribution, and R factors have been determined. Ferrites and their nano-composites, under applied magnetic field up to 20 KOe, exhibited the hysteresis loops of ferromagnetic nature with maximum saturation magnetization of 51.68 emu/g shown by CoFe2O4. The electromagnetic shielding parameters (various shielding effectiveness and reflection loss) and microwave absorbing properties were measured in X band frequency region (8.2-12.2 GHz). Nano-composites show promising and enhanced EMI shielding behavior with overall highest SE value of 52 dB shown by CoFe2O4 composite

Efficient Electrode Material based on Carbon Cloth Supported Polyaniline/Reduced Graphene Oxide Composites for Supercapacitor Application

Nowadays, world energy infrastructure is being stretched due to imbalance between energy production and energy consumption; renewable & sustainable energy storage and conversion techniques could resolve this issue. Thus global energy requirements, limited availability of fossil fuels and environmental crisis drive the expansion of alternative or non- conventional energy sources with high energy and power densities. Electrochemical capacitors or supercapacitors, with a combined form of high power density and energy density, have acquired a stunning acceptance towards the field of electrochemical energy storage. Supercapacitors are used in electric vehicles, mobile phones, digital cameras, wearable devices, portable devices and uninterruptible power supplies (UPS) etc. Here, we have reported the binder free carbon cloth supported polyaniline/reduced graphene oxide (PRGO) composite hydrogel as a high performance supercapacitor electrode synthesized by a facile chemical polymerization method using phytic acid (PA). The electrochemical performance of binder free carbon cloth based PRGO composite hydrogel electrode has been analysed using cyclic voltammetry (CV), and galvanostatic charge-discharge (GCD) techniques. The high specific capacitance (CS) ~ 235.32 F g-1 has been obtained for the PRGO composite hydrogel @cc in 1 M H2SO4. The electrochemical results show that the binder free carbon cloth based PRGO composite hydrogel electrode is a promising candidate for supercapacitors

Efficient Electrode Material based on Carbon Cloth Supported Polyaniline/Reduced Graphene Oxide Composites for Supercapacitor Application

68-74Nowadays, world energy infrastructure is being stretched due to imbalance between energy production and energy consumption; renewable & sustainable energy storage and conversion techniques could resolve this issue. Thus global energy requirements, limited availability of fossil fuels and environmental crisis drive the expansion of alternative or non- conventional energy sources with high energy and power densities. Electrochemical capacitors or supercapacitors, with a combined form of high power density and energy density, have acquired a stunning acceptance towards the field of electrochemical energy storage. Supercapacitors are used in electric vehicles, mobile phones, digital cameras, wearable devices, portable devices and uninterruptible power supplies (UPS) etc. Here, we have reported the binder free carbon cloth supported polyaniline/reduced graphene oxide (PRGO) composite hydrogel as a high performance supercapacitor electrode synthesized by a facile chemical polymerization method using phytic acid (PA). The electrochemical performance of binder free carbon cloth based PRGO composite hydrogel electrode has been analysed using cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) techniques. The high specific capacitance (CS) ~ 235.32 F/g has been obtained for the PRGO composite hydrogel @cc in 1 M H2SO4. The electrochemical results show that the binder free carbon cloth based PRGO composite hydrogel electrode is a promising candidate for supercapacitors

Shielding and dielectric properties of sulfonic acid-doped π-conjugated polymer in 8.2–12.4 GHz frequency range

This article deals with dielectric and electromagnetic interference shielding properties of the polyaniline doped with dodecyl benzene sulfonic acid (DBSA) synthesized by microemulsion polymerization of aniline in aqueous solution of DBSA. Dielectric constant and shielding effectiveness due to absorption (SEA) were calculated using S-parameter obtained from the vector network analyzer in 8.2–12.4 GHz frequency range. Maximum SEA of 26 dB (>99%) was achieved for polymer sample. The real part ε′ of complex permittivity shows small variation, whereas the imaginary part ε″ is found to decrease with the increase in frequency. Different formulations have been performed to see the effect of monomer to dopant ratio on intrinsic properties of polyaniline. Further characterization of polymer was carried out by UV–visible and thermal gravimetric analysis, whereas the conductivity measurements were carried out by the four-probe method

Synthesis of ferrofluid based nanoarchitectured polypyrrole composites and its application for electromagnetic shielding

The monodispersion of magnetic nanoparticles in conducting polymer is the prerequisite to make a high quality composite for tunable electromagnetic interference (EMI) shielding. To meet this challenge, we have designed and synthesized ferrofluid based nanoarchitectured polypyrrole composites containing Fe3O4 (8-12 nm) via in situ oxidative polymerization. To tune the microwave signals, polypyrrole composites (PFF) with different monomer/ferrofluid weight ratios have been prepared and characterized in microwave frequency domain. A maximum shielding effectiveness value of SEA(max)) = 20.4 dB (similar to 99% attenuation) due to the absorption of microwave has been observed in the frequency range of 12.4-18 GHz and attenuation level varied with ferrofluid loading. The electrical conductivity of PFF composite is of the order of 10(-2) S cm(-1) order and having superparamagnetic nature with saturation magnetization (M-s) of 5.5 emu g(-1). The lightweight PFF composites with high attenuations can provide full control over the atomic structure and are favorable for the practical EMI shielding application for commercial electronic appliances

Conjugated polymer nanocomposites: Synthesis, dielectric, and microwave absorption studies

Nanocomposites of polyaniline with barium ferrite and titanium dioxide (TiO2) are synthesized via in situ emulsion polymerization. The transmission electron microscopy (TEM) and high resolution TEM result shows the formation of array of nanoparticles encapsulated within the polymer chains during the synthesis process. The high value of microwave absorption, 58 dB (>99.999% attenuation) results from the combined effect of the nanoparticles and the polymer matrix. The amount of barium ferrite has the profound effect on permittivity (ε), permeability (μ), and microwave absorption of the nanocomposite. The contribution to the absorption value comes mainly due the magnetic losses (μ″) in barium ferrite and dielectric losses (ε″) in TiO2 and polyaniline