Controllable Explosion of Nanobomb by Modifying Nanocontainer and External Shocks

Abstract

The effects of physicochemical modification of carbon nanotubes (CNTs) on the explosion dynamics of a nanobomb, comprising nitromethane confined in CNTs, were investigated using nonequilibrium reactive molecular dynamics and density functional theory (DFT) calculations. CNTs with chirality, nitrogen-doping, and monovacancy defect were utilized. All modifications commonly reduced the time for nanobomb bursting under thermal shock and led to an overall similar reaction pathway. Bursting time of chirality-modified nanobomb was shortened by inferior mechanical property, whereas nitrogen-doping and monovacancy modification reduced the time by increased chemical reactivity (i.e., facilitated attachment of reaction intermediates to the nanocontainer). DFT calculations showed that nitrogen-doping and introducing monovacancy defects lowered the activation energy and heat of formation of the Stone−Wales defects and induced high binding energy of the intermediates, whereas chirality modification alone was ineffective. In addition, decomposition of the nanobomb was initiated via another two heating methods (i.e., electric spark and electromagnetic induction). Under a continuous electric field, bursting of nanobomb with electromagnetic induction was much faster due to oscillating frequency. This theoretical exploration of the effects of physicochemical modification of the nanocontainer and the explosion-initiation methods on the explosion of nanobombs provides in-depth understanding of a confined nanostructured high-energy material.

The role of electric field on decomposition of CL‐20/HMX cocrystal: A reactive molecular dynamics study

“…Two kinds of EFs were considered here, CEF and OEF. The OEF took the form employed in Jeon et al, 23…”

“…This, as well as the special advantage of ReaxFF in dealing with the simulation of reactions in large system, may be the main reasons for the wide use of ReaxFF to study the effect of EF on complex reactions 23,[38][39][40][41] and obtaining results comparable to experiments. 39 So, we believe that ReaxFF-lg force field can give a reasonable insights into the role of EF in the decomposition of the cocrystal.…”

“…These values, may higher than that used in real experiments, were used primarily to allow the simulation to finish in a reasonable time, and they are also within the range of the intensity used in previously reported simulations. [20][21][22][23] As a whole, both CEF and OEF can heat the system with different trends and increasing rates of temperature. Under CEF (Figure 2A), we can see a two-stage heating mechanism ascribed to continuous collision of fractured fragments and the exothermic heat in decomposition process, which is consistent with the case of nitromethane nanobomb 23 and the characteristics of electric spark initiated detonation process that EM is heated first and then self-ignited.…”

“…[20][21][22][23] As a whole, both CEF and OEF can heat the system with different trends and increasing rates of temperature. Under CEF (Figure 2A), we can see a two-stage heating mechanism ascribed to continuous collision of fractured fragments and the exothermic heat in decomposition process, which is consistent with the case of nitromethane nanobomb 23 and the characteristics of electric spark initiated detonation process that EM is heated first and then self-ignited. 43 In contrast, due to coupling with the IR mode of the molecules, the temperature of OEF immediately started to rise even at a lower intensity than CEF, as shown in Figure 2B,C.…”

“…17 As a matter of fact, the sensitivity of explosive is easily affected by external conditions. Evidences have suggested that external electric field (EF) plays important roles in chemical reactions 18 and ignition of EMs, such as increasing the sensitivity, 19 reducing bond activation energy, 20 accelerating decomposition, [21][22][23] and even initiating fast decomposition directly. 24 However, understanding of the roles of EF in decomposition of EMs is yet to be established and the detailed mechanism is scarce.…”