Thermal Transport in 3D CNT-graphene and CNT-CNT Networks
Vikas Prakash (Case Western Reserve Univ), Jungkyu Park (Case Western )
Symposium in honor of Rod Clifton on the occasion of his 75th Birthday
Mon 2:40 - 4:00
Salomon 101
Rapid progress in the synthesis and processing of materials on nanometer length scale has provided exciting new possibilities for combining carbon nanotubes (1D) and graphene (2D) to develop novel 3D nanostructured materials. In this talk, we will present results of a MD study using AIREBO interatomic potential to analyze thermal transport in SWCNT-graphene junctions, which combine single layer graphene floors and (6, 6) SWCNT columns. Two possible junction types are studied to investigate the effect of sp2 and sp3 hybridization on thermal transport at the SWCNT-graphene junctions. Reverse Non-Equilibrium Molecular Dynamics simulation is used to obtain both in-plane as well as out-of-plane thermal conductivity in the two types of CNT-graphene structures as a function of interpillar distance and pillar height and analyze the role of the interface thermal boundary resistance at the SWCNT-graphene junctions. We also estimate the phonon densities of states in the carbon nanotube column, graphene floor, and SWCNT-graphene junctions, in order to better understand thermal transport in the carbon nanotube-graphene junctions. In addition to pillared SWCNT-graphene structures, we investigate thermal transport in CNT-CNT network structures. We employ the Polymer Consistent Force Field to analyze phonon scattering in the branched carbon nanotube structures using the phonon wave packet method. Atom coordinates of a (6, 6) SWCNT are carefully manipulated to create three different CNT-CNT junctions with 45, 60, and 90 degree branch angles. Phonon dispersion relations and eigenvectors for each phonon modes are calculated from 1,000 unit cells of (6, 6) SWCNT using small displacement method and used to create wave packets on branched carbon nanotube structures. Four phonon modes, i.e. the longitudinal acoustic, twisting, transverse acoustic, and the radial breathing mode, are employed to study phonon energy transfer through the various CNT-CNT junctions.