▎ 摘　　要

Strengthening and functioning effects of Fe3O4 nanowires (Fe3O4 NWs)-reduced graphene oxide (FeNWs-rGO) hybrid on gas barrier, microwave absorption, and electromagnetic interference (EMI) shielding performance of epoxy (EP) composites were systematically evaluated. FeNWs-rGO hybrid was successfully prepared through dopamine (DA) derived one-pot coprecipitation, associated with the synchronous surface reduction on GO. The in situ growth mechanism of Fe3O4 NWs on rGO sheets was properly discussed, in which the DA/Fe3+/Fe2+ molar ratio and pH value in the reaction solution were found to be the determining factors in obtaining high quality FeNWs-rGO with a large amount and long length of Fe3O4 NWs. The magnetism feature of FeNWs-rGO endowed the possibility of controlling their distribution state in EP matrix under the action of external magnetic field. The oxygen transmission and moisture diffusion coefficients of EP composites with magnetically aligned FeNWs-rGO at the intensity of 35 mT were clearly reduced as much as 33.6% and 68.0% compared with those of EP composites with randomly distributed FeNWs-rGO, respectively. More importantly, EP composites with different FeNWs-rGO distributions exhibited obvious anisotropy in microwave absorption and EMI shielding performance. Specifically, when FeNWs-rGO was aligned vertical to the direction of incident wave, the remarkable microwave absorption and EMI shielding capabilities of EP composites were achieved at only 2.0 wt % loading content of FeNWs-rGO, mainly due to strong interfacial polarization effect induced by plentiful heterointerfaces and strengthened multiple reflections inside FeNWs-rGO sheets by maximizing their interaction area with the incident wave.