Graphene modification for preparation of stable nanofluids

International audienceCarbon-based nanomaterials, such as carbon nanotubes or graphene, are recognized to be excellentcandidates for high performance materials. Graphene which is a layer of sp2 hybridized carbon atomswith a thickness of only one atom possesses various magnificent properties that are not shared byother materials [1]. Their excellent intrinsic thermal properties have, in particular, led a stronginterest for heat transfer applications [2]. However, dispersion of such material in water to preparestable nanofluids is highly difficult. And the dispersion issue is pointed out to be the main reason forthe reported disappointing and contradictory results in term of performance of such nanofluids [3].Indeed carbon nanoparticles are usually strongly hydrophobic and tend to separate from the liquidmedium, aggregate and sediment. Graphene being a new material, its efficient and controlled surfacemodification is still challenging. Our paper proposes different ways to chemically modify theproperties of graphenic materials in order to increase their hydrophilic character improving that waytheir dispersion. Chemical reactivity of graphene upon the applied treatments was deeply analyzedbased on the carried out multi-scale characterization of the modified graphene. We will discussgraphene reactivity in comparison with other nanostructured carbon materials. Rheologicalproperties of the prepared graphene dispersions will be presented and discussed regarding thepractical use of such dispersions under flowing conditions for heat transfer applications