Magnetically-functionalized self-aligning graphene fillers for high-efficiency thermal management applications

We report on heat conduction properties of thermal interface materials with self-aligning "magnetic graphene" fillers. Graphene enhanced nano-composites were synthesized by an inexpensive and scalable technique based on liquid-phase exfoliation. Functionalization of graphene and few-layer-graphene flakes with Fe3O4 nanopartides allowed us to align the fillers in an external magnetic field during dispersion-of the thermal paste to the connecting surfaces. The filler alignment results in a strong increase of the apparent thermal conductivity and thermal diffusivity through the layer of nano-composite inserted between two metallic surfaces. The self-aligning "magnetic graphene" fillers improve heat conduction in composites with both curing and non-curing matrix materials. The thermal conductivity enhancement with the oriented fillers is a factor of two larger than that with the random fillers even at the low similar to 1 wt.% of graphene loading. The real-life testing with computer chips demonstrated the temperature rise decrease by as muchas 10 degrees C with use of the non-curing thermal interface material with similar to 1 wt.% of the oriented fillers. Our proof-of-concept experiments suggest that the thermal interface materials with functionalized graphene and few-layer-graphene fillers, which can be oriented during the composite application to the surfaces, can lead to a new method of thermal management of advanced electronics. (C) 2015 Elsevier Ltd. All rights reserved.