Hydride- and boron-free solid hypergolic H₂O₂-ignitophores

The race and competition in aerospace technologies based on environmentally friendly green propulsion systems with green fuels and oxidizers are attracting a significant attention. Development of hybrid propulsion systems that use a hypergolic fuel and green H₂O₂ oxidizer, capable of deep throttling and restarting from “cold”, is a very challenging task. Here, we describe a new synthetic approach for the synthesis and characterization of conceptually new hydride- and boron-free, and air/moisture stable solid H₂O₂-hypergols, based on Cu and Co complexes of bis(5-tetrazolyl) amine (H₂BTA) ligand. Among prepared and evaluated materials, the best performing compound [K₂(H₂O)₂Cu(BTA)₂]n (JD-4) was found to exhibit short ignition delay time of 7 ms (with H₂O₂, 97%), and high thermostability of 343 °C. Based on obtained ignition results, X-ray crystallography and HASEM software calculations, structure-hypergolic activity-relationship studies were conducted. We found that the electron density difference between Cu and BTA units should be in a specific range (~2) for these compounds to ignite, providing a valuable tool for further development of novel, green, solid fuels for propulsion systems.