Abstract: Single-wall carbon nanotubes (SWCNTs) have attracted significant attention as a thermal management material because of their high thermal conductivity and excellent thermal stability. However, decreasing the great thermal contact resistance at the tube-tube junctions of SWCNT assemblies is a prerequisite for its practical applications. We report a strategy to address this issue by welding the junctions of SWCNTs together and introducing hexagonal boron nitride (h-BN) encapsulating layers to the surface of the SWCNT bundles. By changing the partial pressure of the BN precursor in a two-step atmospheric-pressure chemical vapor deposition process, amorphous BN nanoparticles and crystalline h-BN were deposited to weld and encapsulate the SWCNT network in sequence. The introduction of the BN led to an in-plane thermal conductivity ∼ 3.8 times higher than that of the SWCNT film, as measured by optothermal Raman method. Molecular dynamics simulations demonstrate that the BN welding and encapsulating facilitate thermal transport by reducing thermal resistance at the tube-tube junctions. Our work brings new insights into facilitating the heat transport in low-dimensional nanomaterial assemblies through structural design.

Key words: Single-wall carbon nanotubes, Boron nitride, Chemical vapor deposition, Thermal conductivity, Encapsulation