Tailoring the properties of ADN using co-crystallisation

Abstract. Co-crystallisation is a technique that can alter the performance properties of existing energetic materials (EMs) by changing the physical and chemical properties of crystalline solids. Ammonium dinitramide or ADN is a white salt comprising ammonium ions and dinitramide ions. ADN is a powerful oxidising agent because it has a high oxygen content. It also has high nitrogen content and is a green propellant because it is halogen-free. However, is very hygroscopic and has a relatively low melting point. In terms of sensitivity, ADN has a low impact sensitivity compared to ammonium perchlorate (AP). The drawbacks are the main problem of using ADN. In the past decade, there have been several reports about co-crystals of energetic materials, but interestingly there are only three concerning co-crystals of ADN. Moreover, three of them successfully used neutral molecules as the co-formers. In this research, the first co-crystals of ADN with other energetic salts have been successfully synthesised via crystal engineering. The crystals were studied by single-crystal X-ray diffraction. The physiochemical and energetic properties, including density, thermal stability, hygroscopicity, impact sensitivity and calculated energetic performance (e.g., detonation velocities and detonation pressures) of ADN could be adjusted using crystal engineering. The new components exhibit favourable physical and energetic properties, which are improved over ADN.