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Pi-stacked interactions in explosive crystals: buffers against external mechanical stimuli
Chaoyang Zhang1, Xiaochuan Wang, Hui Huang
1Laboratory of Material Chemistry, Institute of Chemical Materials, China Academy of Engineering Physics, P.O. Box 919-327, Mianyang, Sichuan, PR China 621900. zcy19710915@yahoo.com.cn
Journal of the American Chemical Society
|June 6, 2008
Summary
Pi-stacked interactions in explosives like TATB help buffer mechanical energy, reducing sensitivity. Planar pi-stacked structures effectively absorb impact, preventing detonation by converting mechanical energy into intermolecular forces.
Area of Science:
- Materials Science
- Computational Chemistry
- Chemical Engineering
Background:
- Explosive crystal packing influences sensitivity.
- Pi-stacked interactions are crucial in some energetic materials.
- Understanding these interactions is key to designing safer explosives.
Purpose of the Study:
- Investigate pi-stacked interactions in explosives under mechanical stress.
- Correlate pi-stacking structures with impact sensitivity.
- Elucidate the role of pi-stacking in buffering mechanical energy.
Main Methods:
- Molecular simulations of 2,4,6-trinitrobenzene-1,3,5-triamine (TATB) under slide and compression.
- Comparative analysis of TATB (planar pi-stacking), Fox-7 (wavelike pi-stacking), and HMX (no pi-stacking).
- Examining changes in electrostatic and van der Waals attractions.
Main Results:
- Layer sliding in TATB decreases electrostatic attraction while slightly decreasing vdW attraction.
- Compression along the c-axis in TATB increases vdW attraction as electrostatic attraction decreases.
- Planar pi-stacked structures effectively buffer mechanical stimuli by converting energy.
Conclusions:
- Pi-stacked structures, especially planar ones, enhance explosive safety by absorbing mechanical energy.
- This energy conversion into intermolecular forces prevents molecular vibration, hot spot formation, and detonation.
- Pi-stacking offers an additional mechanism for low sensitivity in explosives beyond stable molecular structures.
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