Boron nanoparticles prepared by milling in the presence of a hypergolic energetic ionic liquid (EIL) are suspendable in the EIL and the EIL retains hypergolicity leading to the ignition of the boron. This approach allows for incorporation of a variety of nanoscale additives to improve EIL properties, such as energetic density and heat of combustion, while providing stability and safe handling of the nanomaterials.

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International audienceA total of 38 ionic liquids (19 of which are new) comprised of 13 cations, 1-propargyl-3-methyl-imidazolium, 1-allyl-3-methyl-imidazolium, 1,3-dimethyl-imidazolium, 1-ethyl-3-methyl-imidazolium, 1-butyl-3-methyl-imidazolium, 1-methoxyethyl-3-methyl-imidazolium, 1-methyl-4-butyl-1,2,4-triazolium, 1-methyl-4-allyl-1,2,4-triazolium, 1-methyl-4-amino-1,2,4-triazolium, N-butyl-N-methyl-pyrrolidinium, N-allyl-N-methyl-pyrrolidinium, N-allyl-pyridinium, and N-butyl-3-methyl-pyridinium, paired with three anions, dicyanamide, azide, and nitrocyanamide, have been prepared, characterized, and evaluated as potential hypergolic fuels by determining key physical, thermal, and ignition properties. The reactivity of these ionic liquids (32 liquids and 6 solids which melt below 100 degrees C) was strongly correlated to increased electron density in the cation, while small changes in physical properties had little effect beyond a certain threshold, suggesting that subtle changes in chemical reactivity can greatly influence the hypergolic ignition pathway

The structure of two different energetic ionic liquids and the nature of their binding to elemental boron surfaces were investigated by a combination of X-ray photoelectron spectroscopy, IR spectroscopy, zeta potential measurements, thermogravimetric analysis, and first-principles theory. It was found that both 1-methyl-4-amino-1,2,4-triazolium dicyanamide ([MAT][DCA]) and 1-butyl-3-methylimidazolium dicyanamide ([BMIM][DCA]) ionic liquids bind to boron well enough to resist removal by ultrasonic washing and to protect the boron surface from oxidation during air exposure of the washed powder. The data suggest that both the cation and the anion of the ionic liquids interact with the boron surface; however, for [MAT][DCA], the interaction of the cation appears to dominate, while for [BMIM][DCA] the interaction with the [DCA]− anion dominates. The difference is attributed to the binding of boron to the amino group of [MAT]+, and the amino group also appears to help bind a thicker ionic liquid (IL) capping layer.

Space-qualified lubricants: Graphene and graphene oxide (r-GO) can strongly improve the low-temperature performance of hypergolic ionic liquids by reduction of viscosity. Key to success is to match the graphene type to the specific ionic-liquid functionality.

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Azolium azolates from reactions of neutral azoles with 1,3-dimethyl-imidazolium-2-carboxylate, 1,2,3-trimethyl-imidazolium hydrogen carbonate, and N,N-dimethyl-pyrrolidinium hydrogen carbonate †

Figure 3. Ignition delay of graphene or r-GO dispersions in [MAT][DCA] versus temperature. Angewandte Chemie 3