New Mechanism For Slow Explosives

High explosives rich in carbon react far more slowly than those with less carbon—on the order of milliseconds, instead of nanoseconds. Scientists have believed that the detonation process is slower in the carbon-rich materials because of the formation of graphitic or diamond-like particles. But now, chemist M. Riad Manaa of Lawrence Livermore National Laboratory and colleagues have discovered an entirely different mechanism that may explain the relatively sluggish reaction of carbon-rich explosives (J. Am. Chem. Soc., DOI: 10.1021/ja808196e). Using both density functional-based tight-binding theory and molecular dynamics simulations, the group modeled the shock compression of a particularly insensitive explosive, 1,3,5-triamino-2,4,6-trinitrobenzene (TATB), and found that during the process, nitrogen-rich heterocyclic clusters form, slowing the reaction. These clusters remain intact for much of the simulation, which is "a testament to their resiliency toward further decomposition and further retardation of chemical activity," the authors write.