Magnetically Aligned Fe₃O₄ Nanowires-Reduced Graphene Oxide for Gas Barrier, Microwave Absorption, and EMI Shielding

Abstract

Strengthening and functioning effects of Fe 3 O 4 nanowires (Fe 3 O 4 NWs)-reduced graphene oxide (FeNWs-rGO) hybrid on gas barrier, microwave absorption, and electromagnetic interference (EMI) shielding performance of epoxy (EP) composites were systematically evaluated. FeNWs-rGO hybrid was successfully prepared through dopamine (DA) derived onepot coprecipitation, associated with the synchronous surface reduction on GO. The in situ growth mechanism of Fe 3 O 4 NWs on rGO sheets was properly discussed, in which the DA/Fe 3+ /Fe 2+ molar ratio and pH value in the reaction solution were found to be the determining factors in obtaining high quality FeNWs-rGO with a large amount and long length of Fe 3 O 4 NWs. The magnetism feature of FeNWs-rGO endowed the possibility of controlling their distribution state in EP matrix under the action of external magnetic field. The oxygen transmission and moisture diffusion coefficients of EP composites with magnetically aligned FeNWs-rGO at the intensity of 35 mT were clearly reduced as much as 33.6% and 68.0% compared with those of EP composites with randomly distributed FeNWs-rGO, respectively. More importantly, EP composites with different FeNWs-rGO distributions exhibited obvious anisotropy in microwave absorption and EMI shielding performance. Specifically, when FeNWs-rGO was aligned vertical to the direction of incident wave, the remarkable microwave absorption and EMI shielding capabilities of EP composites were achieved at only 2.0 wt % loading content of FeNWs-rGO, mainly due to strong interfacial polarization effect induced by plentiful heterointerfaces and strengthened multiple reflections inside FeNWs-rGO sheets by maximizing their interaction area with the incident wave.

Superparamagnetic ZnFe2O4 Nanoparticles-Reduced Graphene Oxide-Polyurethane Resin Based Nanocomposites for Electromagnetic Interference Shielding Application

“…The increase in ionic radii, hopping length for the octahedral and tetrahedral site, tetrahedral and octahedral bond length, tetrahedral edge, and shared and unshared octahedral edge for prepared ZnFe2O4 nanoparticles with an increase in sonication time is associated with The magnetic characteristics of the superparamagnetic ZnFe 2 O 4 nanoparticles component in the developed nanocomposites provided a degree of magnetic loss such as natural resonance and eddy current loss. It improves the impedance matching between complex permittivity and permeability, which provides well absorption condition for elec-tromagnetic waves [95]. The improved electromagnetic wave shielding characteristics of the ZS100-RGO-PUR nanocomposite can be primarily attributed to the inclusive acts of magnetic loss, dielectric loss, and appropriate attenuation constant derived from various nanofillers in the matrix.…”

Designer Fe3O4@Ag Core–Shell Porous Nanospheres for Enhanced Electromagnetic Interference Shielding of Polymer Nanocomposites

“…This value is comparable with other reported values. [39][40][41][42] The presence of multiple pores in the Fe 3 O 4 @Ag core-shell PNSs contributes to internal reflection and absorption. [43] Essentially, the porosity increases the permittivity and enhances the impedance matching.…”

Hydrogel-based composites beyond the porous architectures for electromagnetic interference shielding

“…The design of porous structures plays a crucial role in improving EMI SE [81][82][83][84][85]. Compared with the ordered pore design of hydrogels, there has been a surge in research on aerogels with aligned pore structures [36,86,87]. In contrast to the disordered pore structures, ordered or aligned pore structures make aerogels highly anisotropic, which results in unique EMI shielding performance as well as mechanical properties.…”