Reducing Kapitza resistance of graphene-paraffin interfaces by alkyl functionalisation

Paraffin waxes are a promising material for heat storage. Improvement of the thermal conductivity can be obtained by adding graphene nanofillers, but interfacial thermal resistance (ITR) forms a problem. Reduction of ITR by functionalisation of the graphene was previously shown possible in the liquid state. For application in heat storage, the thermal properties in solid state are equally important. In the present study, the most optimal reduction of ITR in the solid state was shown for octyl functional groups; in both molten and solid samples, a striking reduction by 95% as compared to pristine graphene was achieved.