Sensitivity of thermal conductivity of carbon nanotubes to defect concentrations and heat-treatment

In the present work, we use reverse non-equilibrium molecular dynamics with adaptive intermolecular reactive empirical bond order interatomic potential to investigate sensitivity of thermal conductivity in (6, 6) single-walled carbon nanotubes (SWCNTs) to side-wall defects and high temperature heat-treatment. Effects of two side-wall defect types and their concentrations are evaluated: chemisorbed hydrogen adatoms on the SWCNT side wall and point vacancy defects. The results of the simulations indicate that the degree of hydrogenation and vacancy concentrations have very similar detrimental effects on the thermal conductivity of (6, 6) SWCNTs. Vacancy repair is evident with heat treatment, and heat-treatment temperatures of 3000 C for up to 22 ns are found to transform point vacancies into various non-hexagonal side-wall defects. The vacancy repair is accompanied by an approximately 10% increase in thermal conductivity. In addition, thermal conductivity measurements in both heat-treated and non-heat treated chemical vapor deposition grown multi-walled carbon nanotubes (MWCNTs) are reviewed. The results of the study suggest that thermal conductivity of carbon nanotubes (CNTs) can be drastically increased if measures are taken to remove common defects from the carbon nanotube side-walls.