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 (SE T ) 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 SE T 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 SiO 2 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.