Anchoring Carbon Nanotubes onto Polyimide-Derived Vertical Carbon as Supporter of Paraffin for Thermal Interface Materials with High Thermal Conductivity

Phase-change materials (PCMs) used as thermal interface materials suffer from the problems of low thermal conductivity and leakage during phase-change processes. Here, a carbon supporter with a vertical hierarchical thermal conductivity structure was designed and provided the PCMs for rapid heat transfer. The supporter of the PCMs was readily prepared from carbonization of commercial polyimide tape coated with carbon nanotubes. The as-obtained supporter was composed of vertical polyimide-derived carbon, in-situ-formed silicon carbide, and interwoven carbon nanotubes, forming a hierarchical thermally conductive nanostructure. In the vertical direction, the polyimide-carbonized straight carbon framework can reduce phonon scattering during heat transfer and greatly improve the thermal conductivity. The in-situ-formed silicon carbide fibers connected the carbon framework with carbon nanotubes, integrating the conductive pathways together. As for the function of the carbon nanotubes, PCMs like paraffin can be loaded in the interwoven networks with no leakage. Based on the above strategy, a shape-stable composite PCM with high thermal conductivity is obtained. When loading 50 wt.% paraffin wax, the composite PCM displayed a latent heat of 85.29 kJ kg −1 and maintained excellent shape stability, which can be used as a heat buffer for thermal interface materials. Moreover, due to the rational design of the thermally conductive pathways, the thermal conductivity of the composite PCM reached 3.3 W m −1 K −1 , 11.7 times higher than pure paraffin. The results show an effective yet facile strategy for building the thermally conductive pathways in thermal interface materials and hold promising applications. Graphical Abstract