Molecular Simulation of the Self-Agglomeration of Carbon Nanostructures in Various Chemical Environments

Self-assembly of carbon nanostructures in solutions provides a cost-effective means to synthesize uniform vertically-aligned nanostructures with specific morphologies including shapes such as wires, sheets and spherical particles. In addition to facilitating the synthesis of bulk carbon nanomaterial, a complete understanding of the agglomeration mechanics also provides a means to deposit uniform layers of carbon nanostructures on top of substrates to produce molecularly-tailored composites with specific mechanical properties. Self-assembly is a complex dynamical process that involves the interaction between the nanoparticle precursors, the transport properties of the individual precursor molecules as well as the precursor-solvent interactions. Depending on the chemical nature of the solvent used during the process various nanostructures of varying shapes and morphologies can be synthesized starting from individual buckyballs and nanotubes. However, despite its wide range of applications, there is a lack of understanding of the self-assembly of carbon nanoparticles. Some of the key factors that govern the agglomeration process are the π-π interaction of the aromatic carbon nanostructures and their interaction with the solvent molecules. A predictive model for self-assembly, that relates the above parameters to the morphology, therefore needs to account for the specific molecular interactions. We present molecular simulation results that incorporate the above effects and shows that the nature of association of the nanoparticle precursors determines the shape and size of the agglomerate. Furthermore, our results show the dependency of the agglomerate size on the concentration of precursors as well as the ambient temperature.