AbstractThe solid‐solid phase transformation of ϵ‐CL‐20 induced by external conditions is one of the bottlenecks limiting the widespread applications of CL‐20‐based energetic materials. Herein, we report the investigation on the influence of solvent polarity on ϵ‐CL‐20 solid‐solid phase transformation behavior both theoretically and experimentally. Density functional theory (DFT) calculation was performed to evaluate the possibility of ϵ‐CL‐20 phase transformation induced by organic solvent molecules from the perspective of ϵ‐CL‐20 electronic structure and molecular structure variations. Additionally, experimental study of ϵ‐CL‐20 phase transformation induced by 1,2‐dichloroethane, ethanol, and methanol gas environment was conducted. Solvent with higher polarity was confirmed to significantly vary molecular surface electrostatic potential and molecular conformation of ϵ‐CL‐20 molecule. Furthermore, ϵ‐CL‐20 critical phase transformation temperature decreased when using inducing solvent with higher polarity. And the observed maximum phase transformation rate was the one induced by the highest polarity solvent. A four‐parameter model was established to describe the phase transformation process as a function of time based on the experimental results. Possible ϵ‐CL‐20 solid‐solid phase transformation mechanism was proposed. Hopefully, these results will be beneficial for the rational preparation and utilization of CL‐20‐based energetic materials.
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