Design of solvent systems for preparation of ε-CL-20 crystals with high sphericity assisted by molecular simulation†

Abstract

In this work, ε-CL-20 crystals with high sphericity, low sensitivity, and high true density were prepared in binary and ternary solvents using solvent–antisolvent recrystallization. The influence mechanisms of temperature, solvent type and solvent composition on crystal morphology were investigated through molecular dynamics simulations with modified attachment energy model. The results reveal that the crystals obtained in the ethyl acetate + chlorobenzene system at 313.15 K have the highest sphericity of 0.8630. The increase in temperature causes the crystals to become sharper. The crystals in ternary solvents retain morphological characteristics of those in the corresponding binary systems and the sphericities are between the two. In ternary systems, hydrogen bonding interactions are affected by the two antisolvents together, and van der Waals and electrostatic interactions can be influenced either by the combined effects of two antisolvents or predominantly by a single antisolvent. It is feasible to adjust interactions by changing growth environments. The temperature, solvent type and solvent composition can affect the diffusion behaviors of solvent molecules and the antisolvent molecules do not affect their mutual diffusion behaviors. This work provides valuable information for the design and optimization of the preparation process of spherical ε-CL-20 crystals.