Theoretical analysis of the hydration of C60 in normal and supercritical conditions

Thermodynamics of hydration of the C60 fullerene in normal and supercritical conditions is studied through the use of molecular dynamics simulations. The hydration free energy is calculated using the thermodynamic integration technique. It is observed that the hydrophobicity of the C60 in normal water is entropy-driven and characterized by a free energy of about 58 kJ mol−1. Our thermodynamic results indicate that this hydrophobic character is sensitively reduced in a supercritical state near of the critical point and that the solubility of the C60 can be found in the supercritical region by varying pressure and temperature. The simulations reveal that for pressures above 570 bar (at 673 K) and temperatures above 770 K (at pressures of 250 and 350 bar) the solubilization process becomes favorable. Structural and dynamical aspects of supercritical solutions were also analyzed.

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► Solubilization of C60 in supercritical water: In supercritical conditions C60 molecule becomes soluble.
► The solubility increases under higher thermodynamic conditions.
► The hydrophobicity of the C60 in normal water is entropic in nature.
► The solubilization process is more efficient with increasing pressure rather than temperature.