Electromagnetic screening in soft conducting composite-containing ferrites: the key role of size and shape anisotropy

Abstract

Functional nanomaterial embedded lightweight polymer composites have drawn considerable attention across wide ranges of industrial applications. In addition to telecommunication and aerospace utilities, microwave absorbing materials must possess interesting properties that ensure excellent performance, from mechanical features to functionalities. Although conducting polymer composites containing magnetic nanofillers have been utilised widely, choosing the fillers from the library of nanoparticles and their effective dispersion inside the matrix may limit their usage in terms of performance, stability and durability. In order to overcome this bottleneck, herein we explored a facile bottom-up synthetic procedure to fabricate different shapes (spherical, cubic, cluster and flower, for example) and size-controlled Fe₃O₄ nanoparticles, and showed the effect of shape anisotropy and size on the above properties in a model polycarbonate (PC)/polyvinylidene difluoride (PVDF) blend with multiwalled carbon nanotubes as conducting nanofillers. The superior performance in terms of microwave attenuation and mechanical properties was reported for spherically shaped Fe₃O₄ nanomaterials. The excellent dispersibility of small-sized nanospheres was instrumental in the improved consolidated loss tangent values, attenuation constant, and impedance matching and skin depth, synergistically resulting in a shielding efficiency of −38 dB at 18 GHz.