Understanding the Roles of Solution Chemistries and Functionalization on the Aggregation of Graphene-Based Nanomaterials Using Molecular Dynamic Simulations

Microscopic aggregation processes of graphene-related nanomaterials (GNs) (including graphene, graphene oxide, carbon nanotubes, carboxylic carbon nanotubes, fullerene, and fullerol) were explored by molecular dynamic (MD) simulations. The aggregation exhibited a strong dependence on solution chemistries and the presence of oxygen-containing functional groups, and the mechanisms were uncovered. The aggregate configurations observed in MD simulations were consistent with the results obtained using density functional theory calculations. Upon the aggregation, the configurations of the GNs were changed, and the electrical properties were affected. The statistics of the Brownian trajectories of the GNs were investigated and were found to vary in the presence of oxygen-containing functional groups and the pH conditions. In addition, the aggregation behavior of GNs was found to be size- and density-dependent, with the density affecting the aggregation efficiency and the size of the nanostructure. Overall, our studies provide a platform for investigating the aggregation of GNs in water, which can also be employed to investigate the behavior of other nanomaterials.