Design And Characterization Of BH Hypergolic Ionic Liquids

Hypergolic propellants as a kind of propellant with chemical ignition,and have become an important power for rockets and spacecrafts.Although hydrazine and its derivatives possess high performance as propellant fuels,they are becoming less and less favorable because of high toxicity and strong carcinogenicity.Known as negligible vapor pressure,high thermal/chemical stabilities,adjustable structures and low toxicity,energetic ionic liquids?ILs?make up the deficiencies of hydrazine-based propellants,and could become an important research direction of green propellant fuels.In order to improve the specific impulse.Herein,the new ILs were designed and synthesized by introducing nitrogen heteroatom to the anions.The contents are as follows:Six[B₁₂H₁₁NH₃]?-based hypergolic ILs were prepared and confirmed by ¹H and¹³C NMR?IR?ESI-MS and EA.Their physicochemical properties,such as T_m?T_d????H_f?I_sp and t_id were measured or calculated.HILs?1?2?3?with substituents?-CH₃?-C₂H₅?-C₃H₇?showed good thermal stability up to 278.2 ^oC,and HILs?4?5?6?with substituents?-CH₂CH=CH₂?-CH₂C?CH?-CH₂C?N?exhibited high densities as 1.17?1.19?1.15 g·cm^-3,respectively.Compared with the corresponding[B₁₂H₁₂]^2--based salts,the target[B₁₂H₁₁NH₃]?-based salts exhibited:?1?higher HOF(-40.1¹073.0 J·g^-1)and I_sp?274.9²76.8 s?;?2?lower T_m?133.9²27.2 ^oC?.With the balanced properties(T_m,198.3 ^oC;HOF,1073.0 J·g^-1;I_sp,276.8 s),HIL 5 has potential applications as the additives and/or fuels of hypergolic bipropellants.Hydrotris?1,2,4-triazolyl?borate-based hypergolic ILs were designed and prepared.The results show that decomposition temperatures above 220°C,densities 1.13¹.22g·cm^-3,heats of formation 152.4⁴61.1 kJ·mol^-1,density specific impulses 358.2³62.5s·g·cm^-3.Hydrotris?1,2,4-triazolyl?borate-based ILs possess higher heat of formation and higher density specific impulse than the corresponding Dihydrobis?1,2,4-triazolyl?borate-based ILs.In short,[B₁₂H₁₁NH₃]?,Hydrotris?1,2,4-triazolyl?borate-based hypergolic ILs were obtained with the idea of specific impulse improvement.The resulting structures,phase transition temperatures,thermal stabilities,hypergolicity and specific impulse of ILs were measured?or calculated?and fully dicussed.It proves that the two series of ILs have the relatively high specific impulses,which provides the data support and scientific basis for the development of high-specific impulse hypergolic ILs.