Tuning the Crystal Habits of Organic Explosives by Antisolvent Crystallization: The Case Study of 2,6-dimaino-3,5-dinitropyrazine-1-oxid (LLM-105)

Abstract

Crystallization is one of the most important methods in the crystal habit control of explosive products. For this study, the antisolvent crystallization experiments were carried out to tune the crystal habits of 2,6-dimaino-3,5-dinitropyrazine-1-oxid (LLM-105). Dimethyl sulphoxide (DMSO) was used as an organic solvent. Water, methanol, acetic acid, nitromethane, acetone, ethanol, methylene chloride, o-dichlorobenzene, and toluene were selected as antisolvents. The X-shaped, spherical cluster-like, rod-like, needle-like, and dendritic crystals were successfully produced by varying the kind of the antisolvent. These results manifested that the polarity and functional groups of antisolvent molecules played important roles in the crystal habits of LLM-105 explosive. The powder X-ray diffraction (PXRD) and Fourier transform infrared (FT-IR) measurements indicated that these antisolvents just tuned the crystal habit of LLM-105 but did not change the crystal structure. The differential scanning calorimetry (DSC) and thermogravimetry (TG) results of the obtained crystals showed that the crystal habits significantly affected the thermal properties. This study can contribute to the investigation of the mechanism of antisolvent-induced crystal habit modification and screen out the efficient antisolvents.