Efficient Preparation of ADN/PDO Cocrystal and Characterization of the Structure and Properties

Herein，we develop a new method to prepare the ammonium dinitramide/pyrazine-1，4-dioxide（ADN/PDO）cocrystal，which is highly efficient and environmental-friendly due to utilizing the reaction crystallization with pure water as the solvent，and also comprehensively characterized its performance. The morphology and structure of the cocrystal were characterized by optical microscopy（OP），powder X-ray diffraction（PXRD），and single crystal X-ray diffraction（SXRD），respectively. In detail，the ADN/PDO cocrystal was prismatic and formed by the combination of ADN and PDO molecules at a molar ratio of 2∶1. Moreover，the ADN/PDO cocrystal belongs to the monoclinic crystal system with a space group of P21/c，owning a theoretical density of 1.779 g·cm-3 at room temperature. Furthermore，through the differential scanning calorimetric（DSC）measurement，it turned out that the melting point of the prepared ADN/PDO cocrystal is 113.3 ℃，which is 21.3 ℃ higher than that of ADN，and the decomposition temperature is slightly higher than that of ADN，demonstrating good thermal stability of the prepared ADN/PDO cocrystal. Then，the hygroscopicity of the prepared cocrystal，measured by the weight increment method，is significantly low at only 2.6%，while that of ADN is at 45%. In addition，calculated by the NASA CEA，the theoretical specific impulse of the cocrystal reaches 277.9 s while that of ADN is 197.5 s，demonstrating the high energy performance of the cocrystal. In conclusion，the reported method based on the reaction crystallization successfully enables the efficient production of a high-energy，low-hygroscopic ADN/PDO cocrystal，thereby facilitating the further assessment of its application performance. © 2024 Institute of Chemical Materials, China Academy of Engineering Physics. All rights reserved.