The solid–liquid equilibrium behavior of ε-CL-20 in 10 pure solvents and its molecular mechanism

The solubility performance of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane has been investigated by the combination of experimental measurement, solvent parameter analysis, and molecular simulation methods. The solubility in 10 pure solvents at 293.15 K to 343.15 K was determined. It was found that the solubility in nine solvents increased with temperature, except for isoamyl propionate. However, it has the largest solubility in isoamyl propionate (4.36 × 10⁻² ∼ 5.39 × 10⁻²). Additionally, a correlation analysis was performed using four equations, which showed that the NRTL equation provided the best fit (overall average relative deviation = 3.74 %, overall coefficient of determination = 0.991). Moreover, the solvent effect was analyzed by Hansen solubility parameters, predicting good solubility in solvents with R_a(V) ≤ 12.47 MPa^0.5 or Δδ_t ≤ 7.77 MPa^0.5, indicating weak polarity of solvent and weak solvent–solvent intermolecular hydrogen bonds enhance dissolution. Furthermore, molecular electrostatic potential surface and radial distribution function analyses provided that weak hydrogen bonding C-H···O promotes dissolution.