Ionic cocrystals (ICCs) hold significant potential to enhance performances for inorganic salts in fields of pharmaceuticals, photoelectricity, energetic materials, etc. However, the targeted design of ICCs with specific properties remains challenging. Herein, this work addresses the critical hygroscopicity of ammonium dinitramide (ADN), a vital green replacement for ammonium perchlorate (AP), by establishing the cooperative heterosynthon strategy. Specifically, improved binding energy in the cluster analysis revealed that moisture sensitivity originates from synergistic cation-anion interactions, which guided the identification of 3,4-diaminofurazan (DAF) as the optimal coformer through subsequent experimental screening. The resulting ADN/DAF cocrystal achieves unprecedented moisture resistance (critical relative humidity = 84.0% at 25 °C) among all ADN cocrystals, enables substitution for AP even surpassing ADN in specific impulse (272.25 s), and significantly enhances safety performance. Notably, this cocrystal demonstrates superior manufacturability: utilizing commercially available coformers and synthesizing via continuous flow production at the hectogram-scale with >88% yield. Therefore, this work presents an effective strategy for engineering moisture-resistant ionic cocrystals as well as showcasing high potential in applications for green energetic propellants.
Wang et al. (Sun,) studied this question.