title: Single mode phonon energy transmission in functionalized carbon nanotubes.
abstract: Although the carbon nanotube (CNT) features superior thermal properties in its pristine form, the chemical functionalization often required for many applications of CNT inevitably degrades the structural integrity and affects the transport of energy carriers. In this article, the effect of the side wall functionalization on the phonon energy transmission along the symmetry axis of CNT is studied using the phonon wave packet method. Three different functional groups are studied: methyl (-CH(3)), vinyl (-C(2)H(3)), and carboxyl (-COOH). We find that, near Γ point of the Brillouin zone, acoustic phonons show ideal transmission, while the transmission of the optical phonons is strongly suppressed. A positive correlation between the energy transmission coefficient and the phonon group velocity is observed for both acoustic and optical phonon modes. On comparing the transmission due to functional groups with equivalent point mass defects on CNT, we find that the chemistry of the functional group, rather than its molecular mass, has a dominant role in determining phonon scattering, hence the transmission, at the defect sites.
authors.affiliation: Thermal Sciences and Materials Branch, Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright Patterson Air Force Base, Ohio 45433, USA. jonghoon.lee@wpafb.af.mil
authors.forename: Jonghoon
authors.initials: J
authors.lastname: Lee
authors.forename: Vikas
authors.initials: V
authors.lastname: Varshney
authors.forename: Ajit K
authors.initials: AK
authors.lastname: Roy
authors.forename: Barry L
authors.initials: BL
authors.lastname: Farmer
mesh_terms: D004735:Energy Transfer; D037742:Nanotubes, Carbon / Q000737:chemistry*; D060739:Phonons
chemical_list: D037742:Nanotubes, Carbon