Nanophase of water in nano-diamond gel

The nanosized water phase has been discovered while studying differential scanning calorimetry (DSC) of the aqueous gel of nano-diamond particles (diameter ca. 5 nm). Two endothermic peaks were observed in the DSC traces of frozen gel upon warming; a broad peak appeared at 265 K before the melting of bulk water, which is attributed to the melting of nanophase water adsorbed onto the surface of nano-diamond particles. The events can be reproduced in exothermic fashion upon cooling the same sample. The mass of nanophase water per one nano-diamond particle and the melting enthalpy of nanophase water were derived from the DSC data. Similar nanophase water was observed earlier in gels prepared from an aqueous dispersion of C-60 clusters with an average diameter of 68 nm, but the effect was not as distinct as with nano-diamond particles. These results demonstrate that DSC could be a versatile tool to study the stability of carbon nanoparticles in liquid media.