Initiation and Decomposition of Green Energetic Materials

Recently there has been increased interest in high nitrogen content “green” energetic materials which are designed to produce relatively non-toxic decomposition products as part of a push to decrease the environmental impact of energetic materials through all phases of their existence. With the use of a T-Jump/Time-of-Flight Mass Spectrometer (T-Jump/TOFMS) capable of high heating rates (up to 106 K/s), and rapid sampling (resolution = 100 μs), we were able to probe the initiation and decomposition of these green energetics. The samples include 5-amino-1-methyl-1H-tetrazolium dinitramide (MeHAT_DN), 1,5-diamino-4-methyl-1H-tetrazolium dinitramide (MeDAT_DN), 1,5-diamino-1H-tetrazolium nitrate (DAT_N), 1,5-diamino-4-methyl-1H-tetrazolium azide (MeDAT_N3), and 5-aminotetrazolium dinitramide (HAT_DN), and were produced by the Kalpötke group of the Ludwig-Maximilian University of Munich. These materials have the commonality of a tetrazole containing cation species that is paired with a variety of anion structures. During rapid heating there are observed two competing breakdown mechanisms for the cation’s tetrazole ring. There does not appear to be a correlation between the ring breakdown mechanisms and decomposition temperature, but rather with the placement of functional groups along the tetrazole ring. Since the tetrazole structure is a large part of each of these materials, the neutral 5-amino-1H-tetrazole (5-AT) was also tested to compare the decomposition between neutral and ionic species. Decomposition temperature and reaction time within the mass spectrometer are also determined, and for a few materials with slower reaction rates, multiple mechanistic steps can be observed. In a complimentary study several of these materials were tested on a micro-DSC device developed at the National Institute of Standards and Technology (NIST). Due to its small size, this system allows for rapid heating of samples and further investigation of the decomposition temperature and calculation of kinetic parameters under high-heating conditions. Recently there has been increased interest in high nitrogen content “green” energetic materials which are designed to produce relatively non-toxic decomposition products as part of a push to decrease the environmental impact of energetic materials through all phases of their existence. With the use of a T-Jump/Time-of-Flight Mass Spectrometer (T-Jump/TOFMS) capable of high heating rates (up to 106 K/s), and rapid sampling (resolution = 100 μs), we were able to probe the initiation and decomposition of these green energetics. The samples include 5-amino-1-methyl-1H-tetrazolium dinitramide (MeHAT_DN), 1,5-diamino-4-methyl-1H-tetrazolium dinitramide (MeDAT_DN), 1,5-diamino-1H-tetrazolium nitrate (DAT_N), 1,5-diamino-4-methyl-1H-tetrazolium azide (MeDAT_N3), and 5-aminotetrazolium dinitramide (HAT_DN), and were produced by the Kalpötke group of the Ludwig-Maximilian University of Munich. These materials have the commonality of a tetrazole containing cation species that is paired with a variety of anion structures. During rapid heating there are observed two competing breakdown mechanisms for the cation’s tetrazole ring. There does not appear to be a correlation between the ring breakdown mechanisms and decomposition temperature, but rather with the placement of functional groups along the tetrazole ring. Since the tetrazole structure is a large part of each of these materials, the neutral 5-amino-1H-tetrazole (5-AT) was also tested to compare the decomposition between neutral and ionic species. Decomposition temperature and reaction time within the mass spectrometer are also determined, and for a few materials with slower reaction rates, multiple mechanistic steps can be observed. In a complimentary study several of these materials were tested on a micro-DSC device developed at the National Institute of Standards and Technology (NIST). Due to its small size, this system allows for rapid heating of samples and further investigation of the decomposition temperature and calculation of kinetic parameters under high-heating conditions.