A number of energetic ionic liquids (EILs) have been reported as promising hydrazine-replacement fuels for hypergolic rocket propulsion. However, most of these EILs were ignited using corrosive and hazardous concentrated fuming nitric acid. Very significant efforts were recently made to utilize “rocket grade” highly concentrated H₂O₂ (>90%) as a “green” alternative to fuming nitric acid and N₂O₄ oxidizers. Although “rocket grade” H₂O₂ is more challenging to use and less safe for storage than commercially available H₂O₂ (70%), the latter is not considered as a viable oxidizer for hypergolic propulsion. In this work, we focused on the development of novel iodine-rich promoters, capable of initiating hypergolic ignition reactions between a typical EIL fuel – 3-ethyl-1-methyl-1H-imidazol-3-ium cyanotrihydroborate – and H₂O₂. Among the prepared and evaluated promoters, the top performing [FcCH₂NEtMe₂ ⁺]₂[B₁₂I₁₂ ²⁻] compound 5 showed ignition delay times of 45 ms in the reaction of the tested EIL with H₂O₂ (70%) and 17 ms with H₂O₂ (95%). We believe that these findings provide a platform for the development and utilization of commercially available H₂O₂ as a potential “green” oxidizer for rocket propulsion.

New iodocuprate-containing ionic liquids with high thermostability were designed, prepared and evaluated as hypergolic reaction promoters between an energetic ionic fuel and a H₂O₂ “green” oxidizer.

A simple synthetic strategy for the preparation of high nitrogen content azo- and methylene bridged mixed energetic azoles was used. All new compounds were fully characterized by NMR and infrared spectroscopy, elemental analysis, and differential scanning calorimetry (DSC). In addition, the structures of energetic salts 7 and 10 were confirmed by single-crystal X-ray diffraction analysis. Detonation performances, calculated from heats of formation and experimental densities, thermal stabilities, and impact and friction sensitivities suggest possible applications in the field of insensitive energetic materials.