(536f) Mechanical Behavior and Properties of Graphene Nanomeshes

Hu, L., University of Massachusetts Amherst
Chen, M., University of Massachusetts, Amherst
Ramasubramaniam, A., University of Massachusetts Amherst
Maroudas, D., University of Massachusetts Amherst

Graphene nanomeshes (GNMs) are graphene-based metamaterials consisting of a periodic arrangement of nano-scale holes or pores in the graphene lattice with neck widths less than 10 nm, mimicking dense arrays of ordered nanoribbons.  Optimal design of GNMs toward enabling a broad range of technological applications requires the establishment of rigorous structure-property-function relationships in such engineered graphene nanostructures.

In this presentation, we report the results of a systematic computational study on the mechanical behavior and mechanical properties of GNMs based on molecular-statics and molecular-dynamics simulations of uniaxial tensile deformation tests using a reliable bond-order interatomic interaction potential.  Both the mechanical properties and the dynamical response to mechanical loading are determined as a function of the nanomesh architecture, namely, the lattice arrangement of the pores, as well as of the pore morphology, pore size, material density, and pore edge passivation.  To examine effects of pore morphology, we have studied both circular and elliptical pores, varying the ratio of the lengths of the major and minor axes in the elliptical pore shapes.  To examine effects of pore edge passivation, we have studied GNMs with both unpassivated and hydrogen-terminated pore edges.  For the numerous GNM structures examined, elastic moduli are computed and stress-strain curves are generated, which are used to determine the ultimate tensile strength, fracture strain, and toughness as a function of the GNM architectural, morphological, and physicochemical parameters listed above.  The structural responses of the GNMs during their deformation and fracture in the simulated mechanical deformation tests are analyzed in detail and the underlying mechanisms are characterized systematically.  We find that the GNM mechanical behavior undergoes a transition as the GNM density decreases, determine the critical density for the transition, and derive the dependence of this critical density on pore morphology and hydrogen pore edge termination.