▎ 摘　　要

Two-dimension (2D) graphene-like nanosheets with small thickness and large lateral size attract tremendous attention in the application of high-K materials. In this paper, 2D aluminum oxide coated reduced graphene oxide nanosheet (Al2O3@rGO) were fabricated via bottom-up method in expectation of being a kind of promising dielectric filler. Polyimide (PI) based composites filled by different Al2O3@rGO contents were prepared via in-situ polymerization. The characterization results of the composites indicate that strong filler-matrix bonding contributes to improve the compatibility of Al2O3@rGO in PI. Besides, the orientation of Al2O3@rGO nanosheets in the composites is detected by SAXS and SEM. For the composites, the dielectric behaviors, thermal stabilities and mechanical properties were investigated. The results show that the composites possess high dielectric constant and low dielectric loss. Additionally, the composites have good electrical insulation properties. Furthermore, the enhancements in thermal stabilities and mechanical properties of the composites are also observed attribute to the strong interactions between PI and Al2O3@rGO. Consequently, it is hoped that the composites would be possessing potential applications in flexible dielectric materials owing to its enhanced dielectric constant, thermal stabilities and mechanical performances.