Methylene-Bridged Melt-Castable Explosives with Enhanced Thermal Stability and Detonation Performance

The development of conventional melt-castable explosives is limited due to low decomposition temperature and modest detonation performance. This study successfully synthesized a series of melt-castable compounds by coupling 3,5-diamino-4-nitropyrazole with nitrogen-rich heterocycles via a methylene bridging strategy. Most of the synthesized compounds possess suitable melting points (Tm = 76.7–141.2 °C) for melt-castable processing, with decomposition temperatures all exceeding 233.3 °C. Their detonation velocities range from 7918 to 8676 m s–1, significantly surpassing that of TNT (Dv = 6881 m s–1). Particularly noteworthy is hydrazinium salt 9, which combines high thermal stability (Tm = 102.3 °C; Td = 273.1 °C) with excellent detonation performance (Dv = 8676 m s–1), comparable to that of RDX (Dv = 8795 m s–1). These results highlight its promising potential as a candidate material for advanced melt-castable explosive formulations.