Toward the design of robust multilayer graphene: mechanistic understanding of the role played by interlayer interactions

In the literature, while the mechanical responses of multilayer graphene have been investigated during uniaxial tensile stretch and nanoindentation tests, fundamental mechanisms for the effects of the number of layers (non-bonded interlayer interactions) are rarely explored and discussed. In this work, a series of molecular dynamics simulations was performed to bridge this gap. Our results revealed that for graphene samples under tensile stretch, stress–strain relations and Young’s moduli were insensitive to both the interlayer interactions and the number of graphene layers. Contrarily, during nanoindentation tests, layer thicknesses as well as interlayer interactions, play significant roles in determining the force–displacement curves, and thus Young’s moduli of multilayer graphene. Through analyzing strain distributions, the underlying mechanisms for these observations were proposed. While interlayer interactions have insignificant effects on the distribution of normal strains, they can initiate “strain shielding” for the distribution of shear strains. Hybrids of graphene/boron nitride sheets were then built as demonstrations to further validate these findings. The results obtained here not only provide fundamental insights into the role of interlayer interactions, but also shed lights on the design of mechanically robust multilayer graphene.