Thermally conductive polymer foams with sodium-dodecyl-benzenesulfonate-surface-modified graphene nanoplatelets and carbon nanotubes: supercritical CO₂-induced foaming

Lightweight composite foams with high thermal conductivities are difficult to obtain owing to the trade-off between thermal conductivity and porosity. In this study, to improve the dispersion of graphene nanoplatelets (GNP) and multi-walled carbon nanotubes (MWNT) and the uniformity of pore size, sodium dodecyl benzenesulfonate (SDBS) can be used, which acts as a surface modification agent on GNP and MWNT and as a foam stabilizer on supercritical carbon dioxide (scCO₂) foaming. The mixed morphology composite (MMC) network leads to improved thermal conductivity, which is not significantly reduced after scCO₂ foaming. This may be attributed to the fact that the SDBS-assisted MMC networks of GNP and MWNT in polyamide 6 (PA6) are maintained after foaming with the homogeneous pores by scCO₂ and the SDBS stabilizer. Thus, the density of the composite decreases to 1.249g/cm³ after foaming. The resulting high-heat-dissipation composites possess lightweight properties and high thermal conductivities, which are promising for application as battery pack components in next-generation automobiles.