Recently, graphene and carbon nanotubes (CNTs) promise considerable application potentials in the highly efficient thermal management of high-power devices because of their superb thermal conductivity (TC). However, the high electrical conductivity hampers their use in some fields where electrical insulating components are always required. Herein, to coordinate the thermal and electrical conductivity of CNT, fluorinated CNT (FCNT) was first used as a thermally conductive filler to prepare composite film with nanofibrillated celluloses (NFCs) via facile vacuum-assisted filtration. The obtained composite film shows a well-organized layered structure of the building blocks along the planar direction. Moreover, the one-dimensional structure of NFCs and the strong interaction of NFCs and FCNTs ensure sufficient connection between FCNT themselves and the reduced interfacial thermal resistance of NFCs/FCNTs, so that efficient heat transfer pathways can be well reserved, leading to simultaneous accessibility of high in-plane TC of 14.1 W m-1 K-1 and favorable electrical insulation property at an FCNT content of 35 wt %. Despite such a high FCNT loading, the strong interaction between NFCs and FCNTs enables the composite film to possess enhanced toughness, reliable mechanical strength, and flexibility. Therefore, we think that these outstanding comprehensive properties guarantee that the prepared composite film has promising applications in heat dissipation of next-generation portable and collapsible electronic devices.
Keywords: composite film; electrical insulation; fluorinated carbon nanotube; nanofibrillated celluloses; thermal conductivity.