Self-folding and self-scrolling mechanisms of edge-deformed graphene sheets: a molecular dynamics study

Graphene-based nanofolds (GNFs) are edge-connected 2D stacked monolayers that originate from single-layer graphene. Graphene-based nanoscrolls (GNSs) are nanomaterials with geometry resembling graphene layers rolled up into a spiral (papyrus-like) form. Both GNS and GNF structures induce significant changes in the mechanical and optoelectronic properties of single-layer graphene, aggregating new functionalities in carbon-based applications. Here, we carried out fully atomistic reactive (ReaxFF) molecular dynamics simulations to study the self-folding and self-scrolling mechanisms of edge-deformed graphene sheets. We adopted initial armchair edge-scrolled graphene (AESG( , )) structures with similar (or different) twist angles ( , ) in each edge, mimicking the initial configuration that was experimentally developed to form biscrolled sheets. The results showed that AESG(0, 2π) and AESG(2π, 2π) evolved to single-folded and two-folded fully stacked morphologies, respectively. As a general trend, for twist angles higher than 2π, the self-deformation process of AESG morphologies yields GNSs. Edge twist angles lower than π are not enough for triggering the self-deformation processes. In the AESG(0, 3π) and AESG(3π, 3π) cases, after a relaxation period, their morphology transition towards GNSs occurred rapidly. In the AESG(3π, 3π) dynamics, a metastable biscroll was formed by the interplay between the left- and right-sided partial scrolling while forming a unique GNS. At high-temperature perturbations, the edge folding and scrolling transitions to GNFs and GNSs occurred within an ultrafast time-period. Remarkably, the AESG(2π, 3π) evolved to a dual state that combines folded and scrolled structures in a temperature-independent process. Graphene-based nanofolds (GNFs) are edge-connected 2D stacked monolayers that originate from single-layer graphene.