title: Exploring Sustainable Rocket Fuels: [Imidazolyl-Amine-BH2](+)-Cation-Based Ionic Liquids as Replacements for Toxic Hydrazine Derivatives.
abstract: The application of hypergolic ionic liquids as propellant fuels is a newly emerging area in the fields of chemistry and propulsion science. Herein, a new class of [imidazolyl-amine-BH2](+)-cation-based ionic liquids, which included fuel-rich anions, such as dicyanamide (N(CN)2(-)) and cyanoborohydride (BH3CN(-)) anions, were synthesized and characterized. As expected, all of the ionic liquids exhibited spontaneous combustion upon contact with the oxidizer 100 % HNO3. The densities of these ionic liquids varied from 0.99-1.12 g cm(-3), and the heats of formation, predicted based on Gaussian 09 calculations, were between -707.7 and 241.8 kJ mol(-1). Among them, the salt of compound 5, that is, (1-allyl-1H-imidazole-3-yl)-(trimethylamine)-dihydroboronium dicyanamide, exhibited the lowest viscosity (168 MPa s), good thermal properties (Tg <-70 °C, Td >130 °C), and the shortest ignition-delay time (18 ms) with 100 % HNO3. These ionic fuels, as "green" replacements for toxic hydrazine-derivatives, may have potential applications as bipropellant formulations.
authors.affiliation: Research Center of Energetic Material Genome Science, Institute of Chemical Materials, China Academy of Engineering Physics (CAEP), Mianyang, 621900, China.
authors.forename: Shi
authors.initials: S
authors.lastname: Huang
authors.affiliation: Research Center of Energetic Material Genome Science, Institute of Chemical Materials, China Academy of Engineering Physics (CAEP), Mianyang, 621900, China.
authors.forename: Xiujuan
authors.initials: X
authors.lastname: Qi
authors.affiliation: Research Center of Energetic Material Genome Science, Institute of Chemical Materials, China Academy of Engineering Physics (CAEP), Mianyang, 621900, China.
authors.forename: Wenquan
authors.initials: W
authors.lastname: Zhang
authors.affiliation: Research Center of Energetic Material Genome Science, Institute of Chemical Materials, China Academy of Engineering Physics (CAEP), Mianyang, 621900, China.
authors.forename: Tianlin
authors.initials: T
authors.lastname: Liu
authors.affiliation: Research Center of Energetic Material Genome Science, Institute of Chemical Materials, China Academy of Engineering Physics (CAEP), Mianyang, 621900, China. qinghuazhang@caep.cn.
authors.forename: Qinghua
authors.initials: Q
authors.lastname: Zhang
mesh_terms: D000588:Amines / Q000737:chemistry*; D000838:Anions / Q000737:chemistry; D002412:Cations / Q000737:chemistry; D053834:Explosive Agents / Q000138:chemical synthesis / Q000737:chemistry; D006834:Hydrazines / Q000737:chemistry*; D007093:Imidazoles / Q000737:chemistry*; D052578:Ionic Liquids / Q000737:chemistry*; D008962:Models, Theoretical; D014783:Viscosity
chemical_list: D000588:Amines; D000838:Anions; D002412:Cations; D053834:Explosive Agents; D006834:Hydrazines; D007093:Imidazoles; D052578:Ionic Liquids; C029899:imidazole
keywords: hydrazines; hypergolicity; ionic liquids; nitrogen heterocycles; propellants