Nitramine-furoxan compounds, as a kind of energetic materials, have attracted great interest due to their outstanding detonation properties. Nevertheless, conventional molecular frameworks incorporating the 1,2,5-oxadiazole usually exhibit low thermal stability, which limits the practical application of these materials. To address this issue, the replacement of the 1,2,5-oxadiazole with 1,3,4- and 1,2,4-oxadiazole isomers in the nitramine-furoxan framework was employed to enhance the thermal stability. A novel high-performance compound, 3,5-bis(2-nitramino-1,3,4-oxadiazol-5-yl)-1,2,4-oxadiazole (compound 5) was designed and synthesized by cyclization of hydrazide and cyanogen bromide. It is characterized by the substitution of 1,2,4-and 1,3,4-oxadiazole rings for 1,2,5-oxadiazole rings. Simultaneously, three energetic ionic salts (compounds 6-8) were successfully synthesized. Strikingly, dinitroamine-oxadiazole compound 5 exhibits excellent thermal stability ( T d = 167 °C) compared to isomers I-III containing 1,2,5-oxadiazole (I: unstable in air; II: T d = 67 °C; III: T d = 101 °C), while maintaining outstanding detonation properties ( D = 9063 m⋅s -1 , P = 36.4 GPa) approaching those of HMX ( D =9144 m⋅s -1 , P = 39.2 GPa). Structure-property relationships highlight the synergistic effects of 1,2,4-oxadiazole and 1,3,4-oxadiazole in achieving next-generation HEDMs with high thermal stability and outstanding detonation property.
Xu et al. (Sun,) studied this question.