Molecular Dynamics Investigations of the Mechanical Properties of Heterogeneous Structures Composed of Graphene Sheets, Graphene Ribbons, and Boron Nitride Sheets

It is well known that monolayer/multilayer graphene possesses ultra-high elastic modulus and critical stress with intrinsic low toughness. In order to explore ways to reduce its brittleness, in this work we employ atomistic modeling to examine the mechanical properties of mono- and multilayers of graphene, nanoribbons, boron nitride and a range of combinations. Regardless of size, edge type exhibits a significant effect on the critical stress/strain, evidenced by the higher mechanical strength of zigzag compared to armchair ribbons, as well as the armchair direction in graphene sheets. Furthermore, our calculations show that with increasing number of layers the mechanical strength of graphene deviates from that of the monolayer sheet, while in contrast multilayer boron nitride sheets preserve the fracture point of the single layer. Based on these results, we explored a range of heterogeneous structures composed of graphene sheets, graphene nanoribbons, and boron nitride sheets. Under tensile stretch, components in these heterogeneous structures show asynchronous cracking behavior helping to improve the overall toughness. By analyzing interfacial binding/sliding between heterogeneous components, the underlying mechanisms are explored and improved compositions can be proposed.