A Spectroscopic Study on the Reactivity of Boron Bearing Energetic Ionic Liquids in Levitated Droplets - Toward the Development of Boron-Fueled Engines
Abstract
Key Objective: The overall goal of this project is to explore experimentally the fundamental mechanisms involved in the reaction and ignition of prototype boron-based energetic ionic liquids (EILs) - 1-butyl-3-methylimidazolium dicyanoborohydride [BMIM] [DCBH] and 1-butyl-3- methylimidazolium dicyanamide [BMIM] [DCA] doped with passivated nanoparticles - in the presence of reactive and non-reactive gases under combustion like conditions. These findings will be applied to overcome previous limitations of boron-based combustion processes namely the formation of boron oxide (B2O3) and of metaboric acid (HOBO) Ð the thermodynamical sink of boron oxidation. Methodology/Techniques: These objectives are achieved by systematically initiating the reaction and ignition of boron-based EILs in levitated droplets employing a novel ultrasonic levitation device at combustion-relevant temperatures and pressures Ð an emerging laboratory technique, which has not been accessible in previous studies. To identify the products formed in these processes on line and in situ, the levitator incorporates three highly complementary detection schemes eventually revealing the complex reactions and ignition processes of boron-based energetic ionic liquids comprehensively: infrared (IR), Raman (Ra), and ultraviolet Ð visible (UV-VIS) spectroscopy. By conducting these experiments with levitated droplets of boron-bearing EILs and tracing the temporal evolution of the reactants and products on line and in situ spectroscopically, we extract versatile concepts on the decomposition and reaction mechanisms along with the products formed in these processes. These data are of crucial significance to understand boron-mediated combustion processes. Significance: Besides the basic scientific interest from the physical chemistry community (reaction mechanisms) to unravel the decomposition and reaction pathways of boron-based EILs in levitated droplets, the proposed studies have unprecedented implications to the fields of boron combustion chemistry, boron-based chemical propulsion systems, and also to the physicalorganic chemistry community to unravel fundamental decomposition mechanisms of complex organic molecules, to probe isomerization processes of organic transient species, to correlate distinct fragmentation mechanisms with the molecular structure of the molecule, and to advance insights into basic chemical structure and chemical bonding of carbon-, hydrogen-, oxygen-, and boron-bearing molecules formed in these processes. This presents a major challenge as no study has been conducted to date, in which the decomposition and reactions of levitated boron-bearing EILs have been explored on line and in situ in the liquid phase. ONR Relevance: Results from this proposal directly overlap with the goals of the Long Range Broad Agency Announcement for Navy and Marine Corps Science and Technology and with the Naval Science & Technology Strategy - Innovations for the Future on multiple levels. Here, the proposed research addresses the ONR Navel Science & Technology Focus Area Power and Energy connecting to the objective categories Efficient Power & Energy Systems and High Energy and Pulsed Power within the division of Naval Air Warfare and Weapons (Code 35). More specifically, the proposed research tackles subsections ÔfÕ (Energetic Materials) and ÔgÕ (Future Naval Capabilities (FNCs)) seeking to provide enhancements to capabilities identified as needs in the FNC technology gaps. This is achieved by advancing the fundamental understanding of the combustion of boron-based ionic liquids for future Navy use. It further helps to predict the performance and the response of boron-bearing energetic ionic liquids to heat and shock, and assists to model the time-dependence during the ignition stage of explosives.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jun 10, 2016
- Source ID
- N000141612078
Entities
People
- Ralf I Kaiser
Organizations
- Office of Naval Research
- United States Navy
- University of Hawaiʻi System