Tunable CoNi microstructures in flexible multilayered polymer films can shield electromagnetic radiation

Abstract

This paper highlights the outstanding electromagnetic shielding efficiency achieved by constructing layer-wise assembly of polymer films containing CoNi (cobalt-nickel) micro flowers, rods, and microspheres. Following a hydrothermal approach, various CoNi microstructures were synthesized from their metal salt precursors using wet chemistry followed by dispersing them in a PVDF matrix along with conducting multiwalled carbon nanotubes (MWNT) and subsequently hot-compressing them into thin flexible films (of thickness less than 1 mm). Few films were also prepared by dispersing only MWNTs in PVDF to construct a layer-wise assembly following an approach wherein a reflector spacer (PVDF/MWNT composites) is sandwiched between n (n = 0,1,2,3) absorbers (PVDF/CoNi/MWNT composites). The film thickness was adjusted in such a way that the total thickness of each assembly is ca. 0.9 mm. This strategy wherein a reflecting layer is sandwiched between the absorbing layers resulted in an excellent total shielding efficiency (SET) of −41 dB. By careful control of different layers in this layer-wise assembly, we managed to facilitate significant magnetic losses coupled with conducting losses. Therefore, this paper offers a replacement of conventional metallic shields with unique CoNi-based polymer composites for suppressing EM radiation.