Reactive Dynamics Study of Hypergolic Bipropellants: Monomethylhydrazine and Dinitrogen Tetroxide

• Published in: The Journal of Physical Chemistry B
• Main Authors: Liu, Yi, Zybin, Sergey V., Guo, Jiaqi, van Duin, Adri C. T., Goddard, William A., III
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: American Chemical Society 2012
• Subjects: Arctic
• Online Access: https://doi.org/10.1021/jp308351g

To gain an atomistic-level understanding on physical and chemical processes occurring at the interfaces of hypergolic propellants, we carried out the first reactive dynamic (ReaxFF) simulations to study the reactive hypergolic mixture of monomethylhydrazine (MMH) and dinitrogen tetroxide (NTO), in comparison with the ethanol (EtOH) and NTO mixture that is reactive but nonhypergolic. Our studies show that the MMH–NTO mixture releases energy more rapidly than the EtOH–NTO mixture upon mixing the fuels and oxidizers. We found that the major early chemical reactions between MMH and NTO are hydrogen abstractions and N–N bond scissions. The MMH–NTO mixture has more reaction channels than EtOH–NTO based on statistical analyses of chemical reaction events and channels at early stages of the dynamics. Analyzing the evolution of product distribution over reaction time shows that the oxidizer (NO_2) diffuses into the fuels (MMH or EtOH) for the occurrence of reactions, demonstrating the influence of physical mixing on chemical reactions. Our simulations suggest that effective hypergolic systems require fuels with low energy barriers of H abstractions and/or bond scissions and oxidizers with large diffusion mobility for efficient physical mixing. © 2012 American Chemical Society. Received: August 22, 2012. Revised: November 8, 2012. Published: November 13, 2012. This research received support from ARO (W911NF-05-1-0345; W911NF-08-1-0124), ONR (N00014-05-1-0778), and Los Alamos National Laboratory (LANL). Some computations in this work were carried out on the Army HPC system (the Arctic Region Supercomputer Center). We thank Dr. Betsy Rice and Larry Davis for their assistance. This work was also supported by "Shanghai Pujiang Talent" program (Grant No. 12PJ1406500), Science and Technology Commission of Shanghai Municipality, "Recruit Program of Global Expert" ("Thousands plan") in Shanghai, and the Open Grant of State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, P. R. ...