One-directional thermal transport in densely aligned single-wall carbon nanotube films

TL;DR

This study demonstrates nearly perfect unidirectional thermal transport in aligned carbon nanotube films, achieving high anisotropy and showing that heat conduction is dominated by individual nanotubes due to minimal intertube resistance.

Contribution

It provides the first detailed measurement of directional thermal conductivity in aligned CNT films, revealing that heat transport is primarily through individual nanotubes with negligible intertube resistance.

Findings

Thermal conductivity of 43 W/m·K in the alignment direction.

Record-high thermal anisotropy of 500.

Heat conduction dominated by individual CNTs, not intertube resistance.

Abstract

Individual carbon nanotubes (CNTs) possess extremely high thermal conductivities. However, the thermal conductivities and their anisotropy of macroscopic assemblies of CNTs have so far remained small. Here, we report results of directional thermal transport measurements on a nearly-perfectly aligned CNT film fabricated via controlled vacuum filtration. We found the thermal conductivity to be 43 +- 2.2 W m^-1 K^-1 with a record-high thermal anisotropy of 500. From the temperature dependence of the thermal conductivity and its agreement with the atomistic phonon transport calculation, we conclude that the effect of intertube thermal resistance on heat conduction in the alignment direction is negligible because of the large contact area between CNTs. These observations thus represent ideal unidirectional thermal transport, i.e., the thermal conductivity of the film is determined solely by that of individual CNTs.