▎ 摘　　要

With the development of renewable energy resources, polymer-based dielectric materials, as key components in energy storage devices with optimized dielectric property, high-temperature stability, and good processibility, are highly demanded. In this study, p-phenylenediamine (PPD)-modified and L-ascorbic acid (LAA)-reduced graphene oxide (NH2-CRG) nanosheets with significant chemical functionalization and significantly improved dispersity were prepared. Also, polyimide was chosen to be the polymer matrix due to its high-temperature resistance, chemical inertness, and excellent mechanical property. By incorporating NH2CRG into the PI polymer matrix via in situ polymerization, 0.8 wt % NH2-CRG/PI composite material with a dielectric constant as high as 839 and a breakdown strength of 80 kV center dot mm(-1) was obtained. Meanwhile, the 5 wt % weight loss temperature of 0.8 wt % NH2-CRG/PI witnessed a 17.6 degrees C increase compared to pure PI. This work provided a promising strategy to prepare graphenebased materials for high-dielectric applications and a realizable process of fabricating polymer-based dielectric composite materials.