Asymmetric electrical-magnetic composite foams with oriented cells fabricated by supercritical CO2 foaming and thermal stretching for efficient absorption dominated electromagnetic interference shielding

Asymmetric composite foams (TCFAs) based on thermoplastic polyurethane (TPU) containing carbon nanotubes (CNTs) and Fe 3 O 4 -decorated reduced graphene oxide (Fe 3 O 4 @rGO) electrical-magnetic dual networks with oriented cell structures and a silver layer were fabricated through supercritical carbon dioxide foaming, thermal stretching and a knife coating process. The oriented cells prolonged the electromagnetic (EM) wave transmission path and induced more multiple reflections, and the asymmetric silver layer enabled a special “absorption-reflection-reabsorption” mechanism, which contributed to a high electromagnetic interference (EMI) shielding effectiveness (SE) of 89.5 dB with an A value of 0.748 at a relatively low total filler content of 1.784 vol%. By regulating the oriented cell structure and the incorporation of asymmetric design, the TCFA-1 achieved 10 times improvement in EMI SE T with a low EMI SE R of 1.27 dB. This work offers new insights into the design and fabrication strategies for high performance absorption-dominated EMI shielding foams.