▎ 摘　　要

Graphene is generally used for conductive material; it can also be used as a key nanofiller for the insulation material of inverter motors. In this study, a series of polyimide (PI) films were prepared successfully by a conventional two-step polymerization method based on bis[3,5-dimethyl-4-(4-aminophenoxy)phenyl]methane as a diamine and 4,4-(hexafluoroisopropylidene)diphthalic anhydride as a dihydride with different weight percentage graphene oxide (GO) nanosheets as nanofillers. The dielectric constant (epsilon) and dielectric loss (tan ) of these films were measured. The results show good dielectric properties, especially an ultralow epsilon value of 1.41 at 1 MHz with 0.19% GO. This showed that the low epsilon value was caused by a high free volume led by the GO nanosheets and the CF bond. The structure and micromorphology of the PIs were characterized by X-ray diffraction and scanning electron microscopy. (c) 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41385.