Electrically conductive rubbery epoxy/diamine-functionalized graphene nanocomposites with improved mechanical properties

Simultaneous reduction and surface functionalization of graphene oxide (GO) was achieved by refluxing GO with a diamine, polyetheramine (D230) at 95 °C followed by thermal treatment at 120 °C. The D230-treated GO (GO-D230) exhibits a high electrical conductivity of 1.0 S/m, much higher than that of GO, due to the chemical and thermal reduction. The incorporation of GO-D230 significantly improves the electrical conductivity of epoxy, exhibiting a sharp transition from electrically insulating to conducting with a low percolation threshold of 0.78 vol%. With 2.7 vol% of GO-D230, the electrical conductivity of its epoxy nanocomposite is 1.0 × 10−4 S/m, nearly 11 orders of magnitude higher than that of neat epoxy; meanwhile, compared to the low Young's modulus and tensile strength of the rubbery epoxy, those of the nanocomposite are increased by 536% and 269%, respectively.