Mechanical properties of graphyne and its family – A molecular dynamics investigation

In this work a series of carbon allotropes related to graphene, called graphyne, graphdiyne, gaphene-3, graphene-4 and graphene-5 are constructed by connecting two adjacent hexagonal rings with different number of acetylenic linkages. Mechanical properties of these monolayer networks are investigated through acting tensile loads on the architectures and molecular dynamics simulations are performed to calculate the fracture strains and associated ultimate stresses. In the armchair loading case, the fracture strain remains nearly unchanged whereas the ultimate strength degrades gradually with longer acetylenic chains. In the zigzag loading situation, the ultimate strength remains nearly the same whereas the fracture strain improves by a little amount with longer acetylenic chains. Furthermore, Young’s moduli of all the investigated architectures are computed to analyze the material stiffness at the near equilibrium regime. The obtained results show that these structures are mechanically stable with high strength and stiffness. The unique mechanical property variations of graphyne family against armchair and zigzag loads suggest flexible designations towards functional use of this novel material, especially in the direction-dependent nanomechanical applications.