Synergistic effects between carbon nanotube and anisotropy-shaped Ni in polyurethane sponge to improve electromagnetic interference shielding

Ingenious microstructural design and suitable multicomponent strategy remain challenging for efficient absorption-dominated electromagnetic interference (EMI) shielding materials with light weight, low filling levels and thin sample thickness. Herein, a flexible waterborne polyurethane (WPU)/dielectric carbon nanotube (CNT)/magnetic anisotropic Ni (chain or flower) EMI shielding composite sponge based on the unique shielding capsule structure was constructed by a dip-coating process. The results show that increasing the Ni (flower or chain) filler content significantly improves the electrical conductivity and EMI shielding properties of composites. The EMI shielding performances of WPU/CNT/8 wt% Ni flower-melamine foam (MF) and WPU/CNT/8 wt% Ni chain-MF are 42.8 and 46.7 dB, respectively, which exceed those of the composite sponge with only CNTs. The synergistic effect between CNTs and Ni (flower or chain) means that the main EMI shielding mechanism of the composite sponge comes from the absorption process. Importantly, owing to the protection of the WPU layer, the composites exhibit excellent EMI shielding effectiveness (SE) even under severe physical and chemical degradation. This research provides a simple synergistic approach for the design of novel, lightweight, and efficient EMI shielding composites, which show great promise for applications in portable and wearable electronic devices.