Thermodynamics of the formation of water dispersions of graphene and water solutions of the nanostructures based on graphene and gold nanoparticles

The thermodynamics of the formation of water dispersions of graphene and water solutions of the nanostructures based on graphene and gold nanoparticles was studied by the method of differential scanning calorimetry. It is found that the initial process of ultradispergation of nanofillers in water leads to disordering of the thermodynamic systems, which is accompanied by decrease in the specific heat capacity and an increase in the free energy in the both systems. It was first established that process of formation of nanocomposites by evaporation of water leads to a decrease in the entropy and free energy, that is, to the ordering in both thermodynamic systems as a result of the self-aggregation of nanofillers in a dilute water solution. In the water solutions of the nanostructures based on graphene and gold nanoparticles an additional effect of sedimentation of gold nanoparticles in water discovered, which accompanied by a more intense decrease in excess enthalpy, excess entropy and excess free energy compared to water dispersions of the graphene.