▎ 摘　　要

The multifunctional epoxy (EP) composites based on three-dimensional interconnected graphene and carbon nanotubes (CNT) were prepared, in which this carbon network was designed by depositing reduced graphene oxide (rGO) and CNT onto the skeletons of polyurethane (PU) sponge via the layer-by-layer assembly. The hybrid rGO/CNT significantly changed the surface properties of PU, allowing a favorable infiltration of EP resin. The interconnected rGO/CNT contributes to suppress the cracks and arrest the mechanical failure, increasing the ultimate tensile strength by 52% at relatively low loading of 0.35 wt %. The rGO/CNT/PU@EP composite was provided with a good electrical conductivity of 0.01 S/cm, an ultralow percolation threshold of 0.0034 wt %, a gauge factor of 5.2, and the enhanced electromagnetic interference (EMI) shielding effectiveness even at extremely low loading. Simultaneous enhancement in mechanical, electrical, and EMI shielding properties makes the rGO/CNT/PU@EP composite have a promising application in the fields of aerospace, automobiles, and portable electronics.