Insights into the structural features of crumpling graphene nanoribbons†

The exploration of graphene nanoribbons (GNRs) offers promising prospects by leveraging their unique physical properties and expanding their versatile applications. Here, we investigate the crumpling behavior of GNRs via coarse-grained molecular dynamics (CG-MD) simulations. By systematically varying the size and geometry (i.e., width and the aspect ratio), we systematically examine the potential energy, configuration, mechanical state, and internal structure of crumpled GNRs in detail. Our findings indicate that as the size of GNRs increases, the self-adhering and self-folding behaviors during the crumpling process become more pronounced. Crumpled GNRs with large sizes exhibit greater adhesion energy but lower out-of-plane strain energy due to the formation of more planar regions and fewer sharp crumples compared to smaller GNRs. By evaluating the relative shape anisotropy and representative configuration during crumpling, we identify two aspect ratio-dependent crumpling modes for GNRs, namely the edge-bending-dominated (EBD) and sliding- and folding-dominated (SFD) crumpling modes, respectively. Notably, the width-dependent critical aspect ratio controlling the transition between these modes provides valuable insights into understanding and predicting the crumpling behavior of GNRs with varying geometries. Moreover, our assessment of curvature and stress distributions and the cross-sectional patterns of crumpled GNRs further reveals a reduction of mechanical heterogeneity with increased sheet size. Our study highlights the critical role of geometry in the crumpling behavior of GNRs, which has significant implications for the tailored design of crumpled ribbon-like sheet materials.