Thermal and dielectric properties of nanocomposites prepared from reactive graphene oxide and silicon‐containing cycloaliphatic diepoxide

Reactive graphene oxide (GO) with multiple carboxyls or hydroxyls was well dispersed in a liquid silicon-containing cycloaliphatic diepoxide. Upon heating the mixture gradually to 180 degrees C, GO was in situ copolymerized with diepoxide to produce novel graphene/epoxy nanocomposites with the GO contents varied from 0 to 5 wt%. Fourier transform infrared spectra demonstrate that the reactive groups of GO have participated in the polymerization reaction. The composites thus obtained have similar amorphous wide-angle X-ray diffraction patterns to the pure epoxy resin, whereas the peak at 9.54 degrees corresponding to GO aggregations is absent, indicating a homogeneous dispersion of GO within epoxy matrix, which is consistent with the scanning electron microscopy and transmission electron microscopy observations. The influence of the GO incorporation on dielectric properties, viscoelastic behaviors, glass transition temperatures, and thermal stability of GO/epoxy nanocomposites is systematically investigated by means of impedance analyzer, dynamic mechanical analysis, and thermal gravimetric analysis. The results show that the dielectric permittivities (k) of the samples significantly increase from 5.0 to 55 with the GO contents, and the k values are stable in the frequency range up to 1 MHz. The high dielectric permittivity and excellent dielectric stability are extremely important for the fabrication of high-performance electronic devices.