Enhanced thermal conductivity and isotropy of polymer composites by fabricating3Dnetwork structure from carbon-based materials

Graphene-based composite is promising as thermal interface material (TIM) due to its outstanding thermal properties. However, there are some bottlenecks to excellent performance, such as agglomeration of particles and undesirable voids between nanoplatelets. In this work, a composite with three-dimensional (3D) thermally conductive network has been assembled, which combines three kinds of nanofillers varying geometric dimensions. Thermal conductivity (TC) of composite with graphene nanoplatelets (GNPs) and carbon-nanotubes (CNTs) at a weight ratio of 3:1 is around 9% higher than that of GNP-based composite. By the introduction of carbon spheres (CSs), the TC is further increased by 28%. The enhanced thermal property further demonstrated by FLIR infrared camera is attributed to the formation of 3D heat conduction paths by GNPs, CNTs, and CSs, where the GNPs play the role of thermally conductive backbones. The other two components are introduced to attenuate the aggregation and strong thermal anisotropy. Moreover, the TC is confirmed nearly isotropic, which is different from most graphene-based TIMs because of the in-plane alignment. Our results indicate that the apparent synergy endows this 3D nanofiller great potential for heat dissipation applications requiring heat removal in two directions.