An effect of partial chemical modification of the surface of a single-walled carbon nanotube on its thermal conductivity is studied. Numerical simulation of heat transfer showed that partial hydrogenation (fluorination) of a nanotube (addition of hydrogen and fluorine atoms from its outer side) can lead to more than a tenfold decrease in thermal conductivity. When the length of the nanotube increases, its thermal conductivity increases in proportion to the logarithm of the length, whereas the proportionality coefficient decreases with an increase in density of hydrogen or fluorine atoms attached. A thermal conductivity reduction coefficient does not depend on the length of the nanotube, but depends on temperature (the lower the temperature, the stronger the decrease) and density of the attached atoms p . When p < 0.25, an increase in density monotonically decreases the thermal conductivity. A decrease is maximum, when density p is 0.25. If only one half of the nanotube is hydrogenated, this half has a lower thermal conductivity. Such a nanotube becomes anisotropic and can be used as a heat transfer rectifier with no more than two percent rectification efficiency.

Using the method of molecular dynamics, it is shown that thermophoresis of particles (atoms) inside single-walled carbon nanotubes (CNTs) is highly efficient. Placing a particle inside the CNT involved in heat transfer causes it to move in the direction of the heat flow at a constant speed, the value of which weakly depends on the length of the nanotube. The heat flow along the CNT leads to the formation of a constant thermophoresis force for the particles inside. The direction of this force coincides with the direction of heat transfer. The monatomic nature of the particle allowed us to numerically calculate this force and to determine the contribution to this force of interaction with each thermal phonon of the nanotube. It is shown that the magnitude of the force is almost completely determined by the interaction of the particle with long-wave bending phonons of the nanotube, which have a long free run path. Therefore, the speed of the particle movement and the value of the thermophoresis force depend weakly on the length of the nanotube, but are determined by the temperature difference at its ends. Because of this, the mode of thermophoresis of particles inside nanotubes is ballistic, not diffusive.