Absorption-dominated electromagnetic interference shielding composite foam based on porous and bi-conductive network structures

Abstract

With the rapid development of electronic equipment and communication technology, it is urgent to develop composites with absorption-dominated and high electromagnetic interference shielding effectiveness (EMI SE) to prevent secondary pollution of electromagnetic (EM) waves. Herein, an effective strategy is employed to fabricate porous Ni-coated melamine foam (Ni@MF)/multi-walled carbon nanotubes (CNT)/temperature-sensitive microspheres (TSM)/polydimethylsiloxane (PDMS) composite foams with an absorption-dominated EMI shielding mechanism and high EMI SE at low filler loading. The bi-conductive network, including a high-efficiency Ni@MF sponge obtained by electroless plating and ordered arrangement and distribution of CNTs induced by the volume exclusion effect, endows the Ni@MF/CNT/TSM/PDMS composite foam with an extremely high conductivity of 2799.8 S m⁻¹ and excellent EMI SE of 45.3 dB with a low CNT loading of 3.0 wt%. The absorption coefficient (A) exceeding 0.72 indicates the absorption-dominated EMI shielding mechanism due to weakened impedance matching and diversiform dissipation mechanisms. What's more, the hydrophobicity, excellent mechanical properties, stable pH resistance and outstanding EMI shielding durability promote the composite foams to maintain impressive performance even in complex and harsh environments. This work establishes an efficient strategy for the absorption-dominated EMI shielding composite foams with a porous structure and bi-conductive network structure, which reveals prospective applications in intelligent electronic equipment and next-generation communication technologies.