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Parmar SM, Depew DD, Wirz RE, Vaghjiani GL. Structural Properties of HEHN- and HAN-Based Ionic Liquid Mixtures: A Polarizable Molecular Dynamics Study. J Phys Chem B 2023; 127:8616-8633. [PMID: 37776252 DOI: 10.1021/acs.jpcb.3c02649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/02/2023]
Abstract
Molecular dynamics simulations of binary mixtures comprising 2-hydroxyethylhydrazinium nitrate (HEHN) and hydroxylammonium nitrate (HAN) were conducted using the polarizable APPLE&P force field to investigate fundamental properties of multimode propulsion (MMP) propellants. Calculated densities as a function of temperature were in good agreement with experiments and similar simulations. The structural properties of neat HEHN and HAN-HEHN provided insights into their inherent, protic nature. Radial distribution functions (RDFs) identified key hydrogen bonding sites located at N-H···O and O-H···O within a first solvation shell of approximately 2 Å. Angular distribution functions further affirmed the relatively strong nature of the hydrogen bonds with nearly linear directionality. The increased hydroxylammonium cation (HA+) mole fraction shows the influence of competitively strong hydrogen bonds on the overall hydrogen bond network. Dominant spatial motifs via three-dimensional distribution functions along with nearly nanosecond-long hydrogen bond lifetimes highlight the local bonding environment that may precede proton transfer reactions.
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Affiliation(s)
- Shehan M Parmar
- Department of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Daniel D Depew
- Department of Astronautical Engineering, University of Southern California, Los Angeles, California 90089, United States
| | - Richard E Wirz
- Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, Los Angeles, California 90095, United States
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Zhou W, Liu J, Chambreau SD, Vaghjiani GL. Molecular Dynamics Simulations, Reaction Pathway and Mechanism Dissection, and Kinetics Modeling of the Nitric Acid Oxidation of Dicyanamide and Dicyanoborohydride Anions. J Phys Chem B 2020; 124:11175-11188. [PMID: 33210915 DOI: 10.1021/acs.jpcb.0c07823] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Direct dynamics simulations of HNO3 with dicyanamide anion DCA- (i.e., N(CN)2-) and dicyanoborohydride anion DCBH- (i.e., BH2(CN)2-) were performed at the B3LYP/6-31+G(d) level of theory in an attempt to elucidate the primary and secondary reactions in the two reaction systems. Guided by trajectory results, reaction coordinates and potential energy diagrams were mapped out for the oxidation of DCA- and DCBH- by one and two HNO3 molecules, respectively, in the gas-phase and in the condensed-phase ionic liquids using the B3LYP/6-311++G(d,p) method. The oxidation of DCA- by HNO3 is initiated by proton transfer. The most important pathway leads to the formation of O2N-NHC(O)NCN-, and the latter reacts with a second HNO3 to produce O2N-NHC(O)NC(O)NH-NO2-(DNB-). The oxidation of DCBH- by HNO3 may follow a similar mechanism as that of DCA-, producing two analogue products: O2N-NHC(O)BH2CN- and O2N-NHC(O)BH2C(O)NH-NO2-. Moreover, two new, unique reaction pathways were discovered for DCBH- because of its boron-hydride group: (1) isomerization of DCBH- to CNBH2CN- and CNBH2NC- and (2) H2 elimination in which the proton in HNO3 combines with a hydride-H in DCBH-. The Rice-Ramsperger-Kassel-Marcus (RRKM) theory was utilized to calculate reaction kinetics and product branching ratios. The RRKM results indicate that the formation of DNB- is exclusively important in the oxidation of DCA-, whereas the same type of reaction is a minor channel in the oxidation of DCBH-. In the latter case, H2 elimination becomes dominating. The RRKM modeling also indicates that the oxidation rate constant of DCBH- is higher than that of DCA- by an order of magnitude. This rationalizes the enhanced preignition performance of DCBH- over DCA- with HNO3.
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Affiliation(s)
- Wenjing Zhou
- Department of Chemistry and Biochemistry, Queens College and the Graduate Center of the City University of New York, 65-30 Kissena Blvd., Queens, New York 11367, United States
| | - Jianbo Liu
- Department of Chemistry and Biochemistry, Queens College and the Graduate Center of the City University of New York, 65-30 Kissena Blvd., Queens, New York 11367, United States
| | - Steven D Chambreau
- Jacobs, Inc., Air Force Research Laboratory, Edwards AFB, California 93524, United States
| | - Ghanshyam L Vaghjiani
- In-Space Propulsion Branch, Rocket Propulsion Division, Aerospace Systems Directorate, Air Force Research Laboratory, AFRL/RQRS, Edwards AFB, California 93524, United States
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Thomas A, Chambreau SD, Vaghjiani GL. Ignition Delay Reduction with Sodium Addition to Imidazolium-Based Dicyanamide Ionic Liquid. J Phys Chem A 2019; 123:10-14. [PMID: 30543100 DOI: 10.1021/acs.jpca.8b08678] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A range of ionic liquids (ILs) have been synthesized and modeled to better understand the role of the cation in the ignition of hypergolic ionic liquids. Vogelhuber et al. have shown by density functional theory methods that the addition of sodium cations to an ionic liquid promotes ignition with white fuming nitric acid (WFNA) by lowering energy barriers. To validate this prediction, solid sodium dicyanamide (Na+DCA-) was added at various weight percents to 1-butyl-3-methylimidazolium dicyanamide (BMIM+DCA-). The ignition delay was measured for each mixture with WFNA. Overall, it was found that the Na+DCA- lowered the ignition delay by 11 ms at 7 wt %. The calculations done by Vogelhuber et al. appear to be consistent with this observation. The sodium cation may play a role by orienting the anion with the WFNA resulting in the favorable reaction energetics observed.
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Affiliation(s)
- Anna Thomas
- Department of Aeronautics and Astronautics , Stanford University , Stanford , California 94305 , United States
| | - Steven D Chambreau
- ERC Inc. , Air Force Research Laboratory, AFRL , Edwards Air Force Base , California 93524 , United States
| | - Ghanshyam L Vaghjiani
- Aerospace Systems Directorate , Air Force Research Laboratory, AFRL/RQRS , Edwards Air Force Base , California 93524 , United States
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Tian T, Hu X, Guan P, Wang S, Ding X. Density and thermodynamic performance of energetic ionic liquids based on 1-alkyl/esteryl-4-amino-1,2,4-triazolium. J Mol Liq 2017. [DOI: 10.1016/j.molliq.2017.09.024] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Chambreau SD, Koh CJ, Popolan-Vaida DM, Gallegos CJ, Hooper JB, Bedrov D, Vaghjiani GL, Leone SR. Flow-Tube Investigations of Hypergolic Reactions of a Dicyanamide Ionic Liquid Via Tunable Vacuum Ultraviolet Aerosol Mass Spectrometry. J Phys Chem A 2016; 120:8011-8023. [DOI: 10.1021/acs.jpca.6b06289] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | - Christine J. Koh
- Departments
of Chemistry and Physics, University of California, Berkeley, California 94720, United States
| | - Denisia M. Popolan-Vaida
- Departments
of Chemistry and Physics, University of California, Berkeley, California 94720, United States
- Chemical
Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Christopher J. Gallegos
- Propellants Branch,
Rocket Propulsion Division, Aerospace Systems Directorate, Air Force
Research Laboratory, AFRL/RQRP, Edwards
Air Force Base, California, 93524, United States
| | - Justin B. Hooper
- Department
of Materials Science and Engineering, University of Utah, 122 South Central
Campus Drive, Room 304, Salt Lake City, Utah 84112, United States
- Wasatch Molecular Inc., 825 North
300 West, Salt
Lake City, Utah 84103, United States
| | - Dmitry Bedrov
- Department
of Materials Science and Engineering, University of Utah, 122 South Central
Campus Drive, Room 304, Salt Lake City, Utah 84112, United States
- Wasatch Molecular Inc., 825 North
300 West, Salt
Lake City, Utah 84103, United States
| | - Ghanshyam L. Vaghjiani
- Propellants Branch,
Rocket Propulsion Division, Aerospace Systems Directorate, Air Force
Research Laboratory, AFRL/RQRP, Edwards
Air Force Base, California, 93524, United States
| | - Stephen R. Leone
- Departments
of Chemistry and Physics, University of California, Berkeley, California 94720, United States
- Chemical
Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
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Chapela GA, Guzmán O, Díaz-Herrera E, del Río F. Room temperature ionic liquids: A simple model. Effect of chain length and size of intermolecular potential on critical temperature. J Chem Phys 2015; 142:154508. [DOI: 10.1063/1.4917312] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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