The surface properties of 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane after partial solution in nitro esters

The thermophysical properties and surface structure of 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (TNCO) particles before and after their contact with liquid nitro esters were studied by differential scanning calorimetry and small-angle X-ray scattering. The thermophysical properties of TNCO changed after contact with nitro esters, and the temperature range of the transition from the β to δ polymorph broadened. This peculiarity was explained in terms of the fracton theory by changes in the heat capacity of particles related to the formation of nanoscale roughness with a fractal (scale-invariant) organization as a result of surface etching by solvents such as nitro esters, which are thermodynamically “bad” with respect to TNCO. The volume properties of particles did not change. The possibility of determining the fractal dimension of the surface of TNCO particles by differential scanning calorimetry was demonstrated. The rate of heating was then used as a “scale ruler” (“yardstick”), and the temperature range of the transition from the β to δ polymorph, as a measured parameter. The dimension of the surface fractal was also determined by an independent method (small-angle X-ray scattering). The results obtained by the two methods were closely similar.