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The exploration of environmentally friendly hypergolic combinations of ionic liquid fuels and hydrogen peroxide as an oxidizer offers opportunities to replace commonly used conventional toxic, corrosive and carcinogenic hydrazine-based liquid hypergolic combinations. Various research opportunities await regarding the detailed investigations of green hypergolic ionic liquids (HILs) with rocket grade hydrogen peroxide (RGHP, >85% H 2 O 2). In this work, the combustion of HILs 1-ethyl-3-methyl imidazolium cyanoborohydride ([EMIM][BH 3 CN]) and 1-allyl-3-ethyl imidazolium cyanoborohydride ([AEIM][BH 3 CN]), and HIL-additive mixtures with 95% H 2 O 2 has been investigated. A new additive, 1,3-dimethyl imidazolium copper iodide ([diMIM] n [Cu 2 I 3 ] n) was synthesized successfully; a structural investigation was performed through the use of single-crystal x-ray diffraction analysis through which a crystal density of 3.22 g/cm3 was revealed. The physicochemical properties (density, viscosity, and decomposition temperature) as well as performance parameters (ignition delay and specific impulse) of 2 to 15 wt% of [diMIM] n [Cu 2 I 3 ] n in [EMIM][BH 3 CN] were determined. A 15 wt% of [diMIM] n [Cu 2 I 3 ] n exhibited ignition delay time (IDT) values of 13 and 29 ms under fuel-rich and oxidizer-rich conditions, respectively; these IDT values are 100 times lower than those for [EMIM][BH 3 CN]. Interestingly, [diMIM] n [Cu 2 I 3 ] n -[EMIM][BH 3 CN] combinations revealed high density (>0.98 g/cm3), good thermal (>200 °C) and chemical stability, and 5.6–6.0% higher density specific impulse than those found for unsymmetrical dimethyl hydrazine. The additive-promoted hypergolic combustion of HIL with RGHP opens a new avenue to the replacement of conventional toxic hypergolic combinations. [ABSTRACT FROM AUTHOR]

• Hypergolic B H bond encased ionic liquids and zwitterionic fuels were synthesized. • The reactivity of hypergolic fuels with 95% H 2 O 2 was explored. • We investigate the hypergolic fuel blends for hybrid and bipropellant rocket applications. • Boron-based green fuels and hydrogen peroxide can be the alternatives for conventional toxic propellant combinations. Exploring novel green hypergolic fuels ignited with hydrogen peroxide (H 2 O 2) offers a number of opportunities in space propulsion with regard to replacing conventional toxic propellant combinations. The green hypergolic fuels, B H bond-rich zwitterions and ionic liquids (ILs) were synthesized; their hypergolic reactivity was investigated with 95% H 2 O 2. Remarkably, ammonia borane (AB) and 1-ethyl-3-methyl imidazolium borohydride ([EMIM][BH 4 ]) exhibited the lowest ignition delay times of 8.1 and 18.5 ms, respectively. For a comprehensive application, the reactivity of liquid and hybrid fuel blends were studied. A liquid fuel blend, [EMIM][BH 4 ] and methyl imidazolium borane (MIMB) (1:1, w/w) exhibited the ignition delay time of about 35 ms. Further, a solid hybrid fuel blend consisting of 40% AB-paraffin revealed a hypergolic ignition delay time of 9.2 ms. Additionally, the gas phase heat of formation and specific impulse were calculated using G09 and NASA-CEC-71 programs, respectively. The specific impulse of AB was 273 s, which is higher than the stated hypergolic zwitterions. Hence, the B H bond-rich zwitterions and ILs are promising choices for new generation green hypergolic liquid and hybrid rocket propulsion. [ABSTRACT FROM AUTHOR]