Mechanical behavior of interlayer-bonded nanostructures obtained from bilayer graphene

We report a comprehensive computational study of the mechanical behavior of two-dimensional carbon-based nanostructures generated from CC interlayer bonding through chemical functionalization in bilayer graphene, based on molecular-dynamics simulations of uniaxial tensile deformation according to a reliable interatomic bond-order potential. These nanostructures range from superlattices of two-dimensional diamond-like nanodomains embedded in twisted bilayer graphene to fully interlayer-bonded graphene bilayers that constitute two-dimensional diamond-like films. We have analyzed in detail the fracture mechanisms of the nanostructures under tension as a function of the extent of interlayer bonding through chemical functionalization. In most cases, fracture is initiated at the interface between pristine graphene and interlayer-bonded two-dimensional diamond-like domains in the composite structure and subsequently propagates across the material leading to failure through brittle cleavage. However, beyond a certain density of interlayer bonds with specific spatial distribution, there is a transition to ductile failure with a structural response that is characterized by void formation and coalescence.