We report on heat conduction properties of thermal interface materials withself-aligning "magnetic grapheme" fillers. Graphene enhanced nano-compositeswere synthesized by an inexpensive and scalable technique based on liquid-phaseexfoliation. Functionalization of graphene and few-layer-graphene flakes withFe3O4 nanoparticles allowed us to align the fillers in an external magneticfield during dispersion of the thermal paste to the connecting surfaces. Thefiller alignment results in a strong increase of the apparent thermalconductivity and thermal diffusivity through the layer of nano-compositeinserted between two metallic surfaces. The self-aligning "magnetic grapheme"fillers improve heat conduction in composites with both curing and non-curingmatrix materials. The thermal conductivity enhancement with the orientedfillers is a factor of two larger than that with the random fillers even at thelow ~1 wt. % of graphene loading. The real-life testing with computer chipsdemonstrated the temperature rise decrease by as much as 10oC with use of thenon-curing thermal interface material with ~1 wt. % of the oriented fillers.Our proof-of-concept experiments suggest that the thermal interface materialswith functionalized graphene and few-layer-graphene fillers, which can beoriented during the composite application to the surfaces, can lead to a newmethod of thermal management of advanced electronics.
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