Enhanced Dielectric Constant, Ultralow Dielectric Loss, and High-Strength Imide-Functionalized Graphene Oxide/Hyperbranched Polyimide Nanocomposites

Abstract

We achieved for the first time the formation of a charge-transfer complex (CTC) between a novel hyperbranched polyimide (PI) and oligo-imide-functionalized graphene oxide (FGO), aiming for enhancing the dielectric properties of resulting PI–FGO nanocomposites. This novel hyperbranched PI was derived from a new diamine N1,N1′-(4,4′-oxybis(4,1-phenylene))bis(N1-(4-aminophenyl)benzene-1,4-diamine). The imide moieties were integrated on amine-FGO via a step-by-step condensation and thermal imidization approach. This FGO exhibited excellent compatibility with hyperbranched PI because of the formation of a CTC between two domains. In viscoelastic measurements, the dynamic storage modulus and glass-transition temperature of flexible PI–FGO nanocomposites increased linearly with increasing FGO contents. The synthesized nanocomposites revealed high mechanical properties with a tensile strength as high as 1.122 GPa. Thermogravimetric analysis demonstrates that these nanocomposite films exhibit high thermal stabilit...