基于H2O2的自燃离子液体设计合成及性能调控

Ionic liquid propellants may overcome the shortcomings of hydrazine-based propellants such as high volatility and strong carcinogens, and become the potential power of aerospace. Currently, the oxidizers used in ionic liquid propellants are HNO3 or N2O4. Compared with HNO3 or N2O4, H2O2 is more environment-benign since it decomposes as H2O and O2. The H2O2-based ionic liquid propellants possess the advantages in fuels and oxidizer so as to be the more environment-benign and effective propellants. However, the common hypergolic ionic liquids cannot spontaneously ignite with H2O2 as the relatively low oxidation ability of H2O2. Two key points are critically necessary for the study of H2O2-based ionic liquid propellants: (1) design and synthesis of H2O2-based hypergolic ionic liquids; (2) mechanism of the hypergolic reactions between ionic liquids and H2O2, and ignition property regulations. Based on the above problem, this project is proposed to design and synthesize the BH-functionalized hypergolic ionic liquids, and the investigations as follows: The resulting ionic liquids are fully characterized and measured to obtain the relationship between ionic liquid structures and properties. The mechanism of hypergolic reactions is conducted based on the in-situ measurements and real-time monitoring. With the above knowledge, the excellent ignite properties of ionic liquids could be obtained by changing the anion and (or) cation structures of the BH-functionalized ionic liquid so as to achieve the goal of developing new green and efficient hypergolic propellants.

离子液体推进剂可弥补肼类推进剂易挥发、强致癌的劣势，成为一类新型航天动力。目前该研究体系的氧化剂为HNO3或N2O4，与之相比，H2O2环境友好(分解产物为H2O和O2)，H2O2基离子液体推进剂可同时实现在燃料和氧化剂方面的优势，具有更彻底的环保和高效性。但是，H2O2氧化性相对较弱，传统离子液体不能与H2O2发生自燃反应，因此，H2O2基离子液体推进剂研究迫切需要解决两个关键问题：(1) H2O2基自燃离子液体的设计合成；(2) 离子液体与H2O2的自燃反应机理及点火性能调控。针对以上问题，并结合前期探索，本项目拟设计合成富含B-H基团的自燃离子液体，通过离子液体的全面结构表征和性质测定，揭示其结构-物性内在关系；并通过B-H功能化离子液体与H2O2自燃反应的在线测定和实时监控，解析该类离子液体的自燃机理，实现离子液体阴、阳离子结构设计对点火性能的调控，推进绿色高效推进剂的快速发展。

H2O2基离子液体自燃推进剂可在氧化剂和燃料方面同时实现无毒害性，是一类新型的绿色高能自燃推进剂。但由于H2O2的氧化性较弱，存在传统离子液体与之接触无法实现自燃的难题。本项分别以阴、阳离子为基础，设计合成富含B-H基团的离子液体，探讨B-H功能化离子液体的结构性质关系，研究B-H功能化离子液体与H2O2的点火性能和自燃机理。主要的创新性成果如下：（1）设计合成了三类B-H簇阴离子（[B12H12]2-、[B10H10]2-和[B6H7]-）基自燃离子液体，其点火延迟时间提升到近乎极限值（1 ms）。经光谱分析并结合量化计算，证实B-H簇结构具有很好的水热稳定性，解决了常规B-H结构水热稳定性差的问题。簇状结构还有助于提高化合物的密度和能量，其高比冲区间有利于发动机的设计、减少运行过程中能量的损失。（2）设计合成了金属（Cu2+，Ni2+，Zn2+）配位自燃离子液体。结果显示，重金属离子的引入使得[B12H12]2-类配合物具有较高的密度（> 1.2g cm-3）、熔点和热稳定性（Td > 220 °C）。与未引入金属离子的自燃离子液体相比，该类配合物在中心金属离子的催化作用下，具有更优的点火性能（1-19 ms）。（3）提出了阴阳离子共修饰型的B-H多唑基自燃离子液体设计。将阴阳离子同时修饰上“着火点”B-H基团和“能量点”多唑基团，使得阴阳离子能够同时起到调控物性和点火性能的作用，克服了以往阴阳离子单一起效的不足，拓宽了自燃离子液体的设计广度。（4）鉴于富碘离子对H2O2具有强催化分解作用，设计合成了富碘盐促进剂复合B-H基自燃离子液体。结果表明，比冲值随着氧化剂含量的提高呈现先增加后减小的趋势。与H2O2的点火测试发现，纯氨硼烷化合物点火延迟时间为256 ms，加入促进剂1,3-二甲基-2,4-二碘咪唑盐离子液体后，点火延迟时间缩短至50 ms，充分证实了富碘盐可有效提高H2O2基自然离子液体推进剂的点火性能。