Performance of copper(II)-azide with hydrogen bonding as initiating explosive

Abstract

The development of high-performance initiating explosives through energetic complexes is considered a feasible way to satisfy military and civilian applications. Compared with other reported initiating explosives, copper(II)-azide is a more promising candidate due to its stronger initiation ability and green nature. However, its instability towards mechanical and electrostatic stimulation hinders its application. This study aimed to propose an effective strategy for stabilizing highly sensitive and explosive copper(II)-azide via hydrogen bonding with NH2-substituted ligands. Using this method, two highly energetic polymers, [Cu(MAT)(N3)2]n (CMA-1) and [Cu4(MAT)2(N3)8(H2O)]n (CMA-2), based on 1-methyl-5-aminotetrazole (MAT), were synthesized and confirmed by single-crystal x-ray diffraction. The experimental results showed that both CMA-1 and CMA-2 had improved thermal stability and reduced mechanical and electrostatic sensitivities to meet practical applications, demonstrating the feasibility of stabilizing the copper(II)-azide system through hydrogen bonds. Especially, combining a series of advantages, including nontoxic metal (Cu), high nitrogen content (62.5%), high thermal decomposition temperature (223.3 °C), good sensitivities (impact sensitivity = 1.0 J; friction sensitivity = 30 N; electrostatic spark sensitivity = 201.6 mJ), powerful ignition capability (minimum primary charge = 10 mg), and simple synthesis, CMA-2 exhibited comprehensive performance beyond those of all other initiating substances to date. In particular, the electrostatic spark sensitivity (201.6 mJ) is at least 720 times higher than that of the original CA powder (<0.28 mJ), making it a promising candidate for new-generation initiating explosive.