Wool-Ball-Type Core-Dual-Shell FeCo@SiO₂@MWCNTs Microcubes for Screening Electromagnetic Interference

Engineered nanostructure-reinforced lightweight polymer composites with superior electromagnetic (EM) shielding effectiveness (SET) are widely employed in high-end applications such as aerospace and microelectronic devices. Recently, carbon nanotube-based three-dimensional nanostructures have shown enormous potential due to unmatched processability, mechanical, and electronic properties. In this study, we present for the first time, highly permeable FeCo-based core-double shell wool-ball-type microcubes chemically enclosed by dielectric silica and conducting multiwalled carbon nanotubes (MWCNTs) sequentially; the resulting reinforced nanocomposites with low filler loading produced superior SET of −35 dB at 18 GHz for a specimen of 3 mm thickness. The excellent dispersion of microstructures in the soft matrix owing to the encapsulation of hard FeCo magnets by MWCNTs ensures low density and excellent flexibility for high-precision applications. The nanoengineered core-dual shell strategy for fabricating magnetic-dielectric-conducting microcubes ensures strong magnetic loss, coupled with dielectric and conduction loss, respectively, from SiO2 and MWCNT shells. This approach, being unique in terms of nanofabrication and subsequent formulation of lightweight flexible composites, demonstrates a highly efficient way toward designing advanced nanocomposites for cutting-edge shielding application.