2018/01/16 by Alexandre F. Fonseca, Fonseca, Alexandre F., Douglas S. Galvão +1
Materials Science · Chemistry · #Carbon Nanotubes in Composites #Graphene research and applications #Fullerene Chemistry and Applications
paper · pdf · doi:10.48550/arxiv.1801.05354
In spite of years of intense research, graphene continues to produce\nsurprising results. Recently, it was experimentally observed that under certain\nconditions graphene can self-drive its tearing and peeling from substrates.\nThis process can generate long, micrometer sized, folded nanoribbons without\nthe action of any external forces. Also, during this cracking-like propagation\nprocess, the width of the graphene folded ribbon continuously decreases and the\nprocess only stops when the width reaches about few hundreds nanometers in\nsize. It is believed that interplay between the strain energy of folded\nregions, breaking of carbon-carbon covalent bonds, and adhesion of\ngraphene-graphene and graphene-substrate are the most fundamental features of\nthis process, although the detailed mechanisms at atomic scale remain unclear.\nIn order to gain further insights on these processes we carried out fully\natomistic reactive molecular dynamics simulations using the AIREBO potential as\navailable in the LAMMPS computational package. Although the reported\ntearing/peeling experimental observations were only to micrometer sized\nstructures, our results showed that they could also occur at nanometer scale.\nOur preliminary results suggest that the graphene tearing/peeling process\noriginates from thermal energy fluctuations that results in broken bonds,\nfollowed by strain release that creates a local elastic wave that can either\nreinforce the process, similar to a whip cracking propagation, or undermine it\nby producing carbon dangling bonds that evolve to the formation of bonds\nbetween the two layers of graphene. As the process continues in time and the\nfolded graphene decreases in width, the carbon-carbon bonds at the ribbon edge\nand interlayer bonds get less stressed, thermal fluctuations become unable to\nbreak them and the process stops.\n