Self-Driven Graphene Tearing and Peeling: A Fully Atomistic Molecular Dynamics Investigation
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MRS Advances © 2018 Materials Research Society DOI: 10.1557/adv.2018.120
Self-Driven Graphene Tearing and Peeling: A Fully Atomistic Molecular Dynamics Investigation Alexandre F. Fonseca1 and Douglas S. Galvão1,2 1 Applied Physics Department, Institute of Physics “Gleb Wataghin”, University of Campinas UNICAMP, Campinas, São Paulo, CEP 13083-859, Brazil.
2
Center for Computational Engineering and Sciences, UNICAMP, Campinas, São Paulo, Brazil.
ABSTRACT
In spite of years of intense research, graphene continues to produce surprising results. Recently, it was experimentally observed that under certain conditions graphene can selfdrive its tearing and peeling from substrates. This process can generate long, micrometer sized, folded nanoribbons without the action of any external forces. Also, during this cracking-like propagation process, the width of the graphene folded ribbon continuously decreases and the process only stops when the width reaches about few hundreds nanometers in size. It is believed that interplay between the strain energy of folded regions, breaking of carbon-carbon covalent bonds, and adhesion of graphene-graphene and graphene-substrate are the most fundamental features of this process, although the detailed mechanisms at atomic scale remain unclear. In order to gain further insights on these processes we carried out fully atomistic reactive molecular dynamics simulations using the AIREBO potential as available in the LAMMPS computational package. Although the reported tearing/peeling experimental observations were only to micrometer sized structures, our results showed that they could also occur at nanometer scale. Our preliminary results suggest that the graphene tearing/peeling process originates from thermal energy fluctuations that results in broken bonds, followed by strain release that creates a local elastic wave that can either reinforce the process, similar to a whip cracking propagation, or undermine it by producing carbon dangling bonds that evolve to the formation of bonds between the two layers of graphene. As the process continues in time and the folded graphene decreases in width, the carbon-carbon bonds at the ribbon edge and interlayer bonds get less stressed, thermal fluctuations become unable to break them and the process stops.
INTRODUCTION Graphene became a paradigm of the ideal two-dimensional material. Owning one of the most desirable combination of physical, chemical and structural properties [13], graphene and its derivatives (for example, graphene-oxide [4], graphane [5] and graphyne [6]) are considered the ultimate nanostructures for diverse types of applications [7-9]. The special mechanical and structural properties of graphene have been explored in studies involving graphene-metal interfaces [10], strain engineering of its
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