Fluid Filling Impedes Thermal Conduction in Free-Standing, Single-Walled Carbon Nanotubes

Carbon nanotubes are an indispensable testbed for materials properties at the quasi 1D limit, and hold significant promise for use as thermal devices and nanofluidic conduits. While they enable exceptional heat and mass transfer, the interplay between these two of their attributes is largely unexplored territory. Here we use Raman spectroscopy to elucidate the effect of fluid filling on a nanotube’s thermal conductance. We study 17–200 μm long, free-standing segments of individual nanotubes in vacuum, reducing heat transfer pathways to the minimum. We show that a simple heat transfer equation based on Fourier’s law can be applied and extract an average thermal impedance of ~1x10^-3 K m/W due to water filling of a (17,9) nanotube. Our findings support confined fluids to enhance phonon scattering and thereby impede thermal conduction in these and related nanochannels.