Aggregate structure of “single-nano buckydiamond” in gel and dried powder by differential scanning calorimetry and nitrogen adsorption

Gels and dried powders of the single-nano buckydiamond (SNBD) have been studied by means of differential scanning calorimetry (DSC) and gas adsorption methods. Nanophase of water (NPhW) was confirmed in SNBD hydrogel by DSC, wherein the characteristic feature at 265 K was observed and attributed to melting of NPhW. No such feature was observed in commercial agglutinate samples of detonation nanodiamond. The parameters of the DSC peak were independent on the method of the material preparation and reproducible to serve as a fingerprint of SNBD material itself. The same nanophase was found in dried powders of SNBD after they were equilibrated with water vapor in isopiestic experiments. Nitrogen adsorption isotherms of the dried powder demonstrated the presence of nano voids. The characteristic size and volume of the nano voids were almost equal to those of NPhW. Gels and dried powders were easily converted back into SNBD water dispersions. Based on DSC and adsorption data it was concluded that SNBD material, though originally divided into individual diamond crystals (d = 5.2 nm) in the water dispersion, forms stable porous networks as gel and dried powder. Formation of such networks could be explained in terms of Van der Waals or Coulombic interaction between the SNBD particles.