Investigation of the solid–liquid ternary phase diagrams of 2HNIW·HMX cocrystal

Abstract

The influence of temperature and solvent on the solid–liquid ternary phase diagrams of the 2HNIW·HMX cocrystal has been investigated. Ternary phase diagrams were constructed for the 2HNIW·HMX cocrystal in acetonitrile and ethyl acetate at 15 °C and 25 °C. HMX and HNIW showed inconsistent dissolution behavior and congruent dissolution behavior in acetonitrile and ethyl acetate, respectively. In the HMX–HNIW–acetonitrile system, the 2HNIW·HMX cocrystal has a narrow thermodynamically stable region at both temperatures. The cocrystal exhibits a wider thermodynamically stable region in the HMX–HNIW–ethyl acetate system. The results show that the choice of solvent has a crucial influence on the dissolution behavior of the cocrystal and the size and position of each region in the phase diagram, while the temperature has no apparent effect on the overall appearance of the phase diagram. By properly selecting the ratios, the 2HNIW·HMX cocrystal could be prepared by the isothermal slurry conversion crystallization method.