Reversibility of the Hydrogen Transfer in TKX-50 and Its Influence on Impact Sensitivity: An Exceptional Case from Common Energetic Materials,The Journal of Physical Chemistry C

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Reversibility of the Hydrogen Transfer in TKX-50 and Its Influence on Impact Sensitivity: An Exceptional Case from Common Energetic Materials
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2017-09-21 00:00:00 , DOI: 10.1021/acs.jpcc.7b07663
Zhipeng Lu _{1,

2} , Chaoyang Zhang ₁

Affiliation

Hydrogen transfer (HT) has been confirmed to possibly serve as a crucial step to initiate and control the decay of common energetic materials (EMs). Nevertheless, the case of currently thriving energetic ionic salts (EISs), as well as the difference in the HT influence on the properties and performances of common EMs and EISs, is poorly known. In this work, we carry out a comparative study of the HTs of dihydroxylammonium-5,5′-bistetrazole-1,1′-diolate (TKX-50) and β-1,3,5,7-tetranitro-1,3,5,7-tetrazocane (β-HMX), as the candidates of EISs and common EMs, respectively, by means of ab initio molecular dynamics simulations and climbing image nudged elastic band calculations, as well as powder X-ray diffraction (PXRD) detections. As a result, the HT in TKX-50 is found to be significantly different from that in β-HMX in many respects. The HT in TKX-50 can occur reversibly between the adjacent cations and anions as an intermolecular reaction. The HT is in fact a proton transfer and is energetically preferred as a first-step reaction with a relatively low energy barrier, instead of a rate-determining one for the entire decay of TKX-50. In comparison, with respect to HMX, the intermolecular HT unlikely takes place, while the intramolecular one, with a neutral H atom and a relatively high energy barrier, occurs as one of the possible rate-controlling steps toward the entire decomposition. More importantly, the reversible HT in TKX-50 implies a completely novel impact sensitivity mechanism for EMs; i.e., the external impact energy can partly be converted into the chemical energy stored first (when heating to approaching ignition) and dissipated by the chemical energy release subsequently (when cooling), which contributes to low impact sensitivity. This work provides an exception of a prior reaction favoring high impact safety of EMs, relative to those that mostly result in irreversible and disastrous consequences. Thus, this study hopefully extends the fields of both HT and EMs.

中文翻译：

TKX-50中氢转移的可逆性及其对撞击感度的影响：一种常见的含能材料案例

氢转移（HT）已被证实可能是引发和控制常见高能材料（EMs）衰减的关键步骤。然而，目前尚不清楚高能离子盐（EIS）蓬勃发展的情况以及HT对常见EM和EIS的性能和性能的影响的差异。在这项工作中，我们对5,5'-双四唑-1,1'-二醇盐（TKX-50）和β-1,3,5,7-tetranitro-1,3的二羟基di的HT进行了比较研究。，5,7-四唑烷（β-HMX），通过从头算起分别作为EIS和常见EM的候选对象分子动力学模拟和爬升图像微调的弹性带计算，以及粉末X射线衍射（PXRD）检测。结果，发现TKX-50中的HT在许多方面与β-HMX中的HT显着不同。作为分子间反应，TKX-50中的HT可在相邻的阳离子和阴离子之间可逆地发生。实际上，HT是质子转移，在能量上优选作为能量反应相对较低的第一步反应，而不是确定TKX-50整个衰变的速率。相比之下，就HMX而言，分子间HT不太可能发生，而具有中性H原子和相对较高的能垒的分子内HT是朝着整个分解过程可能的速率控制步骤之一。更重要的是，TKX-50中的可逆HT暗示了针对EM的全新的撞击敏感性机制；也就是说，外部冲击能可以部分转换为首先存储的化学能（当加热至接近点火时），然后通过随后释放的化学能（在冷却时）耗散，这导致较低的冲击敏感度。相对于大多数会导致不可逆转和灾难性后果的反应，这项工作提供了一个例外的反应，该反应有利于EM的高冲击安全性。因此，这项研究有望扩展HT和EM的领域。这会导致较低的冲击敏感度。相对于大多数会导致不可逆转和灾难性后果的反应，这项工作提供了一个例外的反应，该反应有利于EM的高冲击安全性。因此，这项研究有望扩展HT和EM的领域。这会导致较低的冲击敏感度。相对于大多数会导致不可逆转和灾难性后果的反应，这项工作提供了一个例外的反应，该反应有利于EM的高冲击安全性。因此，这项研究有望扩展HT和EM的领域。

更新日期：2017-09-21

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