Rearrangement and thermal decomposition of nitromethane confined inside an armchair (5, 5) single-walled carbon nanotube

In this work, the thermal decomposition and rearrangement of nitromethane (NMT) confined inside an armchair (5, 5) single-walled carbon nanotubes [CNT(5.5)] were investigated by using the ONIOM calculations in order to understand the confinement effect of CNT on the initial reactions of nitro-energetic compounds. We found that the activation energy barriers for the NMT-MNT (methyl nitrite) rearrangement, H-migration rearrangement and C-N homolytic dissociation were significantly decreased by the confinement effect of CNT(5, 5), suggesting that the CNT(5, 5) can promote the rearrangement and thermal decomposition reactions of the NMT. In both the isolated and confined cases, the C-N homolytic cleavage was kinetically favorable in view of the relatively low activation barrier. However, the energy barrier of the NMT-MNT rearrangement was lower than that of the H-migration rearrangement reaction due to their confinement in CNT(5, 5). Furthermore, the relative energies of the intermediates generated from the rearrangement and thermal decomposition were also modified by the confinement of CNT(5, 5).