Taming the Hygroscopicity of ADN: Novel Energetic Dinitramide Salts with High Critical Relative Humidity

Abstract

Ammonium dinitramide (ADN) is a promising green energetic oxidizer but suffers from strong hygroscopicity, which limits its engineering applications. Herein, a cationic replacement strategy was adopted to synthesize two novel dinitramide energetic salts (2,5-DAF-DN and PDO–DN) from accessible raw materials via a mild process. This strategy profoundly alters the original hydrogen-bonding network of ADN, transforming it into a highly regular layered packing (for 2,5-DAF-DN) and a cage-like architecture (for PDO–DN), thereby significantly enhancing their structural stabilities. Consequently, the critical relative humidity (CRH) values of 2,5-DAF-DN and PDO–DN are 65% and 74%, respectively, showing significant improvements compared with ADN (CRH = 54%). Furthermore, both salts achieve a superior balance between a high-energy output and low mechanical sensitivity. With their mechanical sensitivities markedly reduced (impact sensitivity: >40 J; friction sensitivity: 240 N), they are established as highly promising candidates for solid propellant applications. Hirshfeld surface and electrostatic potential analyses reveal that strong hydrogen-bonding networks facilitate highly compact structures, thereby enhancing their thermal stability and insensitivity. This work verifies the potential of the assembly strategy of nitrogen-rich heterocyclic cations and dinitramide anions to improve the shortcomings of ADN, thereby providing valuable insights for the design of high-performance energetic materials.