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Rahm M.,KTH Royal Institute of Technology | Rahm M.,Competence Center for Energetic Materials | Dvinskikh S.V.,KTH Royal Institute of Technology | Furo I.,KTH Royal Institute of Technology | Brinck T.,KTH Royal Institute of Technology
Angewandte Chemie - International Edition | Year: 2011

Propeller propellant: The largest nitrogen oxide to date, trinitramide (TNA), has been prepared following extensive quantum chemical studies in which its kinetic stability and several physical properties were estimated. TNA was detected using IR and NMR spectroscopy. The compound is highly energetic and shows promise for cryogenic propulsion and as a reagent in high-energy-density material research. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.


Rahm M.,KTH Royal Institute of Technology | Rahm M.,Competence Center for Energetic Materials | Malmstrom E.,KTH Royal Institute of Technology | Eldsater C.,Swedish Defence Research Agency
Journal of Applied Polymer Science | Year: 2011

To enable future environmentally friendly access to space by means of solid rocket propulsion a viable replacement to the toxic ammonium perchlorate (AP) oxidizer is needed. Ammonium dinitramide (ADN) holds great promise as a green replacement. Unfortunately compatibility issues with many polymer binder systems have hampered the development of ADN-based formulations. Herein we present proof-of-concept of a polymer cure system based on hyperbranched copolymers of 3-ethyl-3-(hydroxymethyl)oxetane (TMPO) and tetrahydrofuran (THF). The partly alkyne-functionalized macromolecules were synthesized in a one-pot procedure. TMPO and THF are found to polymerize in exact ratios, indicating a kinetically controlled buildup of nonrandom composition copolymers. Several of the materials show excellent compatibility with ADN, and rapid curing of the energetic polyglycidyl azide polymer (GAP) have been demonstrated through 1,3-dipolar cycloaddition at 75°C. © 2011 Wiley Periodicals, Inc.


Rahm M.,KTH Royal Institute of Technology | Rahm M.,Competence Center for Energetic Materials | Brinck T.,KTH Royal Institute of Technology
Chemistry - A European Journal | Year: 2010

A thorough theoretical investigation of four promising green energetic materials is presented. The kinetic stability of the dinitramide, trinitrogen dioxide, pentazole, and oxopentazole anions has been evaluated in the gas phase and in solution by using highlevel ab initio and DFT calculations. Theoretical UV spectra, solid-state heats of formation, density, as well as propellant performance for the corresponding ammonium salts are reported. All calculated properties for dinitramide are in excellent agreement with experimental data. The stability of the trinitrogen dioxide anion is deemed sufficient to enable synthesis at low temperature, with a barrier for decomposition of approximately 27.5 kcal mol-1 in solution. Oxopentazolate is expected to be approximately 1200 times more stable than pentazolate in solution, with a barrier exceeding 30 kcal mol-1, which should enable handling at room temperature. All compounds are predicted to provide high specific impulses when combined with aluminum fuel and a polymeric binder, and rival or surpass the performance of a corresponding ammonium Perchlorate based propellant. The investigated substances are also excellent monopropellant candidates. Further study and attempted synthesis of these materials is merited. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.


Rahm M.,Competence Center for Energetic Materials | Rahm M.,KTH Royal Institute of Technology | Brinck T.,KTH Royal Institute of Technology
Journal of Physical Chemistry A | Year: 2010

Mechanistic pathways for the thermal decomposition of the solid-state energetic oxidizers ammonium dinitramide (ADN) and potassium dinitramide (KDN) have been deciphered by carefully considering previously performed experimental studies and using state of the art quantum chemical modeling of molecular clusters. Decomposition is governed by surface chemical processes, involving polarized (twisted) dinitramide anions of reduced stability. Under atmospheric and low-pressure conditions, the rate-determining step for the decomposition of these dinitramide salts is the dissociation into NO2 and NNO 2 radicals. The activation barriers for these steps are estimated to be 30 and 36 kcal/mol for ADN and KDN, respectively. The known stabilizing effect of water is explained by its hydrogen bonding ability, which counteracts polarization of surface dmitramides. The reactivity of ADN toward various chemical environments is likely explained through metastable decomposition radical, intermediates. Donation of hydrogen bonds, antioxidant character, and basicity are properties believed to correlate with a compound's ability to act as a stabilizer for dinitramide salts. © 2010 American Chemical. Society.


Rahm M.,KTH Royal Institute of Technology | Rahm M.,Competence Center for Energetic Materials | Tyrode E.,KTH Royal Institute of Technology | Brinck T.,KTH Royal Institute of Technology | Johnson C.M.,KTH Royal Institute of Technology
Journal of Physical Chemistry C | Year: 2011

Vibrational sum frequency spectroscopy (VSFS) and quantum chemical modeling have been employed to investigate the molecular surface structure of ammonium and potassium dinitramide (ADN and KDN) crystals. Identification of key vibrational modes was made possible by performing density functional theory calculations of molecular clusters. The surface of KDN was found to be partly covered with a thin layer of the decomposition product KNO3, which due to its low thickness was not detectable by infrared and Raman spectroscopy. In contrast, ADN exhibited an extremely inhomogeneous surface, on which polarized dinitramide anions were present, possibly together with a thin layer of NH4NO3. The intertwined use of theoretical and experimental tools proved indispensable in the analysis of these complex surfaces. The experimental verification of polarized and destabilized dinitramide anions stresses the importance of designing surface-active polymer support, stabilizers, and/or coating agents, in order to enable environmentally friendly ADN-based solid-rocket propulsion. © 2011 American Chemical Society.


PubMed | Competence Center for Energetic Materials
Type: Journal Article | Journal: The journal of physical chemistry. A | Year: 2010

Mechanistic pathways for the thermal decomposition of the solid-state energetic oxidizers ammonium dinitramide (ADN) and potassium dinitramide (KDN) have been deciphered by carefully considering previously performed experimental studies and using state of the art quantum chemical modeling of molecular clusters. Decomposition is governed by surface chemical processes, involving polarized (twisted) dinitramide anions of reduced stability. Under atmospheric and low-pressure conditions, the rate-determining step for the decomposition of these dinitramide salts is the dissociation into NO(2) and NNO(2)(-) radicals. The activation barriers for these steps are estimated to be 30 and 36 kcal/mol for ADN and KDN, respectively. The known stabilizing effect of water is explained by its hydrogen bonding ability, which counteracts polarization of surface dinitramides. The reactivity of ADN toward various chemical environments is likely explained through metastable decomposition radical intermediates. Donation of hydrogen bonds, antioxidant character, and basicity are properties believed to correlate with a compounds ability to act as a stabilizer for dinitramide salts.

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