1,3,4-oxadiazole Based Thermostable Energetic Materials: Synthesis and Structure-Property Relationship
The increasing demands from both military and civilian application inspired us to explore novel energetic materials with improved safety and energetic performance. Here a class of C-C bonds bridged polyazole energetic materials (based on 1,3,4-oxadiazole bridged polynitropyrazoles) was synthesized and fully characterized. Quantum computation (two-dimensional (2D)-fingerprint and relevant Hirshfeld surfaces) was performed to study the correlations between structures and physicochemical properties. Additionally, their energetic properties including detonation velocity, detonation pressure, sensitivity as well as thermal stability were fully characterized. Of these, compounds 3a and 3b possess excellent thermal stability (3a: Tdec = 338 °C; 3b: Tdec = 368 °C), desirable sensitivity (IS > 40 J, FS > 360 N) and higher energetic properties (3a: Dv = 8099 m s-1, P = 27.14 GPa; 3b: Dv = 8054 m s-1, P = 26.53 Gpa) than hexanitrostilbene (HNS) (a typical heat resistant explosive: Tdec = 318 °C; Dv = 7612 m s-1, P = 24.30 GPa; IS = 5 J, FS = 240 N). Compound 6b exhibits high decomposition temperature (Tdec = 265 °C), low sensitivity (IS = 30 J; FS = 360 N) and comparable detonation properties (Dv = 8710 m s-1, P = 32.75 Gpa) to RDX. Considering their desirable energetic properties, they could be applied in different classes of energetic materials such as heat resistant explosives (3a, 3b) and secondary explosive (6b), respectively.