Tuning the Shape Anisotropy and Electromagnetic Screening Ability of Ultrahigh Magnetic Polymer and Surfactant-Capped FeCo Nanorods and Nanocubes in Soft Conducting Composites

Abstract

Herein, we demonstrate that very high electromagnetic (EM) shielding efficiency can be achieved by dispersing nanoengineered FeCo anisometric nanostructures in a poly(vinylidene difluoride) matrix in the presence of conductive nanofillers (multiwall carbon nanotubes, MWCNTs). The FeCo nanorods (∼800 nm) and nanocubes (∼100 nm) were fabricated by a facile surfactant and polymer-assisted one-pot borohydride reduction method. The growth mechanism depicted a two-directional growth for cubes, whereas for nanorods, a unidirectional growth pattern across the (110) plane was evident. A total shielding effectiveness (SE) of -44 dB at 18 GHz was achieved for a particular combination of FeCo nanorods and MWCNT, and for nanocube-based composites, it was found to be -39 dB at 18 GHz. It was observed from zero field cooled-field cooled curves that the samples displayed room temperature ferromagnetism. An excellent correlation between high aspect ratio FeCo nanorod and superior EM absorption (89%) was explored, pertaining to the fact that nanorods possessed higher magnetic saturation (177.1 emu/g) and coercivity (550 Oe) in contrast to the nanocubes with similar composition. Furthermore, theoretical insight into the mechanism revealed a high degree of interface scattering between conductive MWCNT and magnetic loss components, giving rise to an excellent synergy between magnetic and dielectric parts.

MnO2‐Magnetic Core‐Shell Structured Polyaniline Dependent Enhanced EMI Shielding Effectiveness: A Study of VRH Conduction

“…When the electromagnetic waves interact with magnetic particles, the magnetic domains or the spins starts to align along the direction of applied magnetic field or in a particular direction. This leads to increase magnetic losses in the shielding materials and hence attenuated the electromagnetic waves . Thus, the high conductivity of the prepared samples determines the dielectric loss and high permeability governs the magnetic loss along with structural heterogeneity, which collectively improves the shielding effectiveness through absorption, as can be depicted from equation (16).…”

Review on Shielding Mechanism and Structural Design of Electromagnetic Interference Shielding Composites

“…At present, the percolation value of electromagnetic shielding materials with a uniform structure is very high, and the electromagnetic shielding effectiveness was 20-30 dB, meeting the commercial conditions. [55][56][57][58][59] Therefore, the structural design of conductive polymers is a current research focus. To ensure good conductivity, we can reduce the percolation value of the material, reduce the production cost, and obtain good mechanical and electromagnetic shielding properties.…”

Synergistic Dual‐Atom Molecular Catalyst Derived from Low‐Temperature Pyrolyzed Heterobimetallic Macrocycle‐N4 Corrole Complex for Oxygen Reduction

“…Graphitic diffraction peaks at 2θ values of 26°, 42.8°, and 44.5° were attributed to the (002), (100), and (101) reflections of MWCNT, respectively, in all catalysts. Furthermore, additional small diffraction peaks at 43.9° and 45.0° observed in PhFCC-600 and PhFCC-700, might correspond to the presence of cobalt/iron metallic phases, [57][58][59][60] which were absent in catalysts obtained below 500 °C (PhFCC-400 and PhFCC-500; Figures 2a,c). Fourier-transform infrared (FT-IR) spectroscopy was also used to analyze the pyrolyzed catalysts, with the results shown in Figure S4, Supporting Information.…”