High electrical conductivity and π-π stacking interface design for tunable electromagnetic wave absorption composite foams

Carbon nanotube (CNT) composite materials with magnetic oxide modification are most commonly used as conductive structures in electromagnetic (EM) wave absorption composites, which are limited by low conductivity and interface performance. Inspired by the adhesion of bionic mussel structure and the similar structures of graphene, a porous heteroatom-doped nanostructure of carbon nanotube-Fe₃O₄/pyrolyzed polydopamine (PPD) was designed and a porous composite foam with resorcinol terephthalaldehyde resin was constructed by the salt template impregnation method. Benefiting from the π-π interactions and conductivity of PPD, the conductivity and mechanical properties of the composite increased by 74 times and 168%, respectively. Moreover, the minimum reflection loss of the resorcinol terephthalaldehyde resin foams (RTFs) was −33.0 dB, and the effective bandwidth reached 8.32 GHz because of the interfacial polarization of the PPD structure and conductivity loss derived from the network structure. This work offers a facile strategy to improve the absorption capacities, absorption broadband, and balance the composite mechanical and conductive properties.