| In this doctoral dissertation, a multi-length scale computational approach is utilized to address various aspects of processing and postprocessing of carbon nanotubes, their properties as a function of nanoscale morphology and defect structure, and their use in several small-size devices.; Chemical Vapor Deposition (CVD) of carbon nanotubes from a gas mixture consisting of methane and hydrogen in the presence of cobalt, nickel or iron catalytic particles in a cylindrical reactor is modeled at the reactor length scale and at atomic length scale. The reactor length-scale model is used to determine the gas-phase fields for temperature, velocity, and various species as well the surface-species coverages and the carbon nanotubes deposition rate. The model is further coupled with a Genetic Algorithm optimization code to determine the process parameters. A kinetic Monte Carlo atomic scale model is developed to simulate the carbon nanotubes growth and defect formation and to reveal the effect which the nominal and local processing conditions may have on the nanotubes morphology and growth rates.; Solubilization of the single-walled carbon nanotubes (SWCNTs) in toluene and the SWCNTs functionalized with poly (PmPV-DOctOPV) polymer in toluene is modeled using molecular dynamics simulations. The results obtained show that the solvation Gibbs free energy for the non-functionalized nanotubes in toluene is small but positive. The toluene solution which contains the PmPV-DOctOPV functionalized SWCNTs, on the other hand, is found to be stable and the type of functionalization can be used for separation of the SWCNT bundles into individual nanotubes.; The lattice contribution to thermal conductivity of SWCNTs is studied using the molecular dynamics based thermal current auto-correlation functions. The results obtained show that quite accurate lattice thermal conductivities can be obtained using computational cells considerably smaller than the phonon mean free path. Furthermore, the chirality is found to affect lattice thermal conductivity by as much as 20% at a comparable nanotube diameter.; Ab-initio density functional theory (DFT) and Green's function combined with the tight-binding method are used to determine the character of molecular-oxygen adsorption, and the effect of molecular-oxygen adsorption and the topological defects on the electrical conductance of SWCNTs. The computational results obtained show that oxygen molecules are physisorbed to the defect-free nanotube walls, but chemisorbed onto the walls containing topological defects. (Abstract shortened by UMI.)... |
