Roughening for Strengthening and Toughening in Monolayer Carbon Based Composites

Three-dimensional (3D) aggregation of graphene is dramatically weak and brittle due primarily to the prevailing interlayer van der Waals interaction. In this report, motivated by the recent success in synthesis of monolayer amorphous carbon (MAC) sheets, we demonstrate that outstanding strength and large plastic-like strain can be achieved in layered 3D MAC composites. Both surface roughening and the ultracompliant nature of MACs count for the high strength and gradual failure in 3D MAC. Such properties are not seen when intact graphene or multiple stacked MACs are used as building blocks for 3D composites. This work demonstrates a counterintuitive mechanism that surface roughening due to initial defects and low rigidity may help to realize superb mechanical properties in 3D aggregation of monolayer carbon.