Chemomechanics control of tearing paths in graphene

Abstract

Owing to its molecular membrane structure, tearing is the predominant fracture mode for a monolayer graphene. Yet, the tearing mechanics of monolayer graphene as a two-dimensional (2D) crystal remains poorly understood. Here, we performed molecular dynamics simulations with reactive force field to determine the fracture path of monolayer graphene under tearing. Our simulations revealed that the chemomechanical tearing conditions play a regulatory role on the edge structures of graphene nanoribbons (GNRs) produced by tearing. In vacuum, the resulting GNR features the armchair edge, whereas in the presence of chemical additives (such as oxygens) to the fracture surface, the resulting GNR edge changes from armchair to zigzag. In addition, due to the large in-plane stretching to out-of-plane bending stiffness ratio of monolayer graphene, tearing causes local bending at the crack tip, giving rise to a fracture mode mixity that also modulates the fracture path. In addition to provide an atomistic understanding of tearing mechanics of 2D crystal membranes, our findings shed light on chemomechanical engineering of GNRs with controlled edge structures.