Control of particle size and shape of ɛ-HNIW in Drowning-out crystallization

The particle size and shape of hexanitrohexaazaisowurtzitane (HNIW) crystals are investigated in drowning-out crystallization. Since the e{open}-HNIW crystals are re-constructively transformed from raw HNIW with polymorphic forms, which are crystallized out by drowning-out crystallization, the particle size and shape of e{open}-HNIW crystals are predominantly determined by the growth process during the phase transformation. Due to contradictory contributions of crystallization conditions on crystal particle size and shape, the crystal particle size and shape are controlled by the antisolvent feeding rate within a range of the antisolvent feeding rate from 0.1-1.0 mL/min at ambient temperature. In addition, the e{open}-HNIW crystals are detected by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy, the thermal energies related with the solid-state phase transition from e{open}-HNIW to γ-HNIW and decomposition of HNIW showing dramatic differences in crystal particle size owing to the significant changes in crystal density using differential scanning calorimetry (DSC) and X-ray diffraction.