The performance of a high explosive is measured by its detonation velocity (v D (km sec À1 )) and detonation pressure (P CJ (kbar)). These parameters are determined by the oxygen balance (OB CO ), [1a] density (1), and heat of formation (DH f ), [1b] the higher the oxygen balance, density, and heat of formation, the better the performance. The energy of traditional polynitro compounds (Scheme 1) is primarily derived from the combustion of the carbon backbone using the oxygen carried by the nitro group. [2] For modern polynitro compounds (Scheme 2), the performance is enhanced not only by an excellent oxygen balance but also by a ring/cage strain which improves both the heat of formation and density. [4] Recently, a new class of energetic compounds containing a large fraction of nitrogen has been investigated. [5][6][7][8] These "high-nitrogen" compounds form a unique class of energetic materials [5a, 9] whose energy is derived from their very high positive heat of formation rather than from the combustion of the carbon backbone or the ring/cage strain (Scheme 3). The high heat of formation is directly attributable to the large number of inherently energetic NÀN and CÀN bonds.High-nitrogen compounds containing polyazides possess even higher heats of formation because their energy content rapidly increases with the number of energetic azido groups in the molecule. However, they are notorious for their extreme sensitivity [10a] to spark, friction, and impact (H 50 ) [10b] as well as poor thermal stability, [10a, 11, 12] so their applications are very limited. Examples include 3,6-diazido-1,2,4,5-tetrazine [13] and cyanuric azide (2,4,6-triazido-1,3,5-triazine; [14] Scheme 4).

No abstract

No abstract

This paper describes the explosive sensitivity and performance properties of two novel high-nitrogen materials, 3,6-bis-nitroguanyl-1,2,4,5-tetrazine (1, (NQ 2 Tz)) and its corresponding bistriaminoguanidinium salt (2, (TAG) 2 (NQ) 2 Tz)). These materials exhibit very low pressure dependence in burning rate. Flash pyrolysis/FTIR spectroscopy was performed, and insight into this interesting burning behavior was obtained. Our studies indicate that 1 and 2 exhibit highly promising energetic materials properties.

Advances in sample nebulization and injection technology have significantly reduced the volume of solution required for trace impurity analysis in plutonium and uranium materials. Correspondingly, we have designed and tested a novel chip-based microfluidic platform, containing a 100-µL or 20-µL solid-phase microextraction column, packed by centrifugation, which supports nuclear material mass and solution volume reductions of 90% or more compared to standard methods. Quantitative recovery of 28 trace elements in uranium was demonstrated using a UTEVA chromatographic resin column, and trace element recovery from thorium (a surrogate for plutonium) was similarly demonstrated using anion exchange resin AG MP-1. Of nine materials tested, compatibility of polyvinyl chloride (PVC), polypropylene (PP), and polytetrafluoroethylene (PTFE) chips with the strong nitric acid media was highest. The microcolumns can be incorporated into a variety of devices and systems, and can be loaded with other solid-phase resins for trace element assay in high-purity metals.