Ion-Exchange Strategy toward Green Energetic Dinitramide Ionic Salts with Ultralow Hygroscopicity and Low Sensitivity

Developing chlorine-free oxidizers that simultaneously combine high energy, low mechanical sensitivity, and moisture resistance remains a major challenge for dinitramide-based energetic materials. Herein, two nitrogen-rich heterocyclic dinitramide salts, 3 and 6, were prepared through aqueous metathesis to investigate the influence of cation structure on their physicochemical and energetic properties. Compound 3 shows a decomposition onset temperature of 170 °C and a stepwise exothermic decomposition process, indicating relatively high thermal robustness. In contrast, compound 6 combines a measured density of 1.83 g cm-3 with a calculated detonation velocity of 8951 m s-1 and a detonation pressure of 35.9 GPa, comparable to those of RDX. No initiation was observed for either salt up to the maximum tested impact energy and friction load of 40 J and 360 N, respectively. Compound 6 also exhibits minimal moisture uptake after exposure to 55% relative humidity at 25 °C for 54 h. EXPLO5 calculations predict maximum specific impulses of 268.6 and 270.0 s for GAP- and NEPE-based formulations containing 45 and 65 wt % compound 6, respectively. These results demonstrate that nitrogen-rich heterocyclic cations provide an effective strategy for balancing the energetic performance, mechanical safety, and moisture resistance of dinitramide-based materials.