Mechanical properties of graphene nanoribbons with disordered edges

Using density functional theory (DFT), we investigate mechanical properties and failure characteristics of chiral and achiral graphene nanoribbons. Specifically, we study the dependence of maximum strength, Young's modulus and failure pattern of nanoribbons on their widths, edge chirality and passivation. Besides investigating nanoribbons with perfect edges, nanoribbons with defective edges are considered and the impacts of the presence of Klein or edge pentagonal defects on the properties of nanoribbons are studied. Our DFT results show that as the width of achiral ribbons are reduced, their strength increases. Moreover, significant size effects on the Poisson's ratio of armchair ribbons and Young's modulus of zigzag ribbons are observed. The DFT modeling predicts that the presence of defects reduce the strength of chiral nanoribbons while defects might counter intuitively increase the Young's modulus of chiral nanoribbons. The first-principle simulations show that achiral nanoribbons always fail along a zigzag surface, however the failure pattern of chiral nanoribbons can be more complicated and be accompanied by the nucleation of other kind of defects such as pentagonal-heptagonal rings prior to failure. (C) 2014 Elsevier B. V. All rights reserved.