Constructing Graphene and Carbon Nanotube “Artery–Vein” 3D Structures on the Surface of Carbon Fibers Using a Magnetic Field to Prepare High‐Strength, Multifunctional Composites

Incorporation of nanofillers in sizing agents typically imparts the intrinsic properties of nanofillers to carbon fiber (CF) composites. Therefore, in this study, ionic liquids (ILs) are combined with carbon nanotubes (CNTs), utilizing the cation–π and π–π interactions between ILs and graphene (G) to facilitate the incorporation of CNTs into the G layers, thereby achieving co‐dispersion assistance. Cobalt ferrite (CFO) is loaded onto G, which has the ability to be oriented on CFs under the influence of a magnetic field and is combined with CNTs to construct an “artery–vein” 3D structure. The uniformly dispersed and oriented 3D structure resulted in enhanced interfacial bonding, leading to a 71.06% improvement in the flexural properties of the prepared composites. Simultaneously, the constructed “artery–vein” 3D structure facilitates the efficient transport of phonons and electrons (“blood”). As a result, the thermal conductivity of the composite reached 2.1 W m −1 K −1 , representing a 101.9% improvement. At the same time, the electrical conductivity of the composite material in the orientation direction was 12.21 S/cm, and the electromagnetic interference shielding effectiveness (EMI SE) reached 42.45 dB. Therefore, this composite material has a broad application prospect in the fields of aerospace manufacturing, thermal management materials, and EMI shielding materials.