Mechanical behaviors of graphene-derived layer-by-layer materials

The graphene-derived materials share the same layer-by-layer hierarchical structures. The in-plane mechanical properties of graphene sheet, interlayer shear properties and graphene sheet size are the dominated factors to determine their mechanical properties. The in-plane tensile and interlayer shear properties of graphene sheet with different types of functional groups and topological defects are studied. Because of the interlayer crosslink, the interlayer shear properties are significantly improved. However, the functional groups serves as defects which weaken the in-plane mechanical properties of graphene sheet. By considering the in-plane deformation of graphene sheet and interlayer shear, a deformable tension-shear chain (DTS) model is proposed to describe the mechanical behaviors of graphene-derived materials. The optimum concentrations of the functional groups in graphene sheet to maximize the stiffness and strength of graphene-derived materials are deduced, which are dependent on the graphene sheet size and type of functional groups.