Synthesis and hypergolic properties of flammable ionic liquids based on the cyano (1H-1,2,3-triazole-1-yl) dihydroborate anion

Abstract

A series of hypergolic ionic liquids (HILs) based on the cyano (1H-1,2,3-triazole-1-yl) dihydroborate anion were synthesized by introducing the {BH₂-CN} moiety into the 1,2,3-triazole anion. This introduction allowed us to improve the self-ignition property and decrease the viscosity of ionic fuels. The synthesized series of HILs exhibited wide liquid operating ranges (>220 °C), high densities (>1 g cm⁻³), low viscosities (as low as 22.48 cP), and ignition delay (ID) times as short as 5 ms by using white fuming nitric acid (WFNA) as the oxidizer. Furthermore, these HILs can be ignited upon contact with a 90 wt% H₂O₂ oxidizer in the presence of iodine.