Simultaneously strengthening, toughening, and conductivity improving for epoxy at ultralow carbonaceous filler content by constructing 3D nanostructures and sacrificial bonds

The combination of high strength , great toughness, and excellent electrical properties for conductive polymer composites is essential for their practical applications. Herein, we demonstrate a strategy to improve simultaneously the strength, toughness, and the electrical conductivity of epoxy resin. This strategy involves constructing compact 3D tannin non-covalent modified graphene/multi-walled carbon nanotube (MWCNT) hybrid network and introducing sacrificial bonds. As a result, with only 0.01 wt% the hybrid filler, the tensile strength , Young's modulus , elongation at break, the mode-I fracture toughness ( K IC ), and strain energy release rates ( G IC ) of the epoxy resin were increased by 23.3%, 44.6%, 41.2%, 114.6%, and 219.3%, respectively. This filler loading is 10 and 15 times lower to obtain comparable improvement in tensile strength and K IC compared with the lowest content reported to date. The composites also display excellent electrical properties in terms of an ultralow percolation threshold (~0.076 wt%).