Studies on CL-20/HMX (2:1) Cocrystal: A New Preparation Method and Structural and Thermokinetic Analysis

A new preparation method for CL-20/HMX (2:1) cocrystal has been established at the laboratory level that is amenable for scale up. Solvent evaporation from a saturated solution of the stoichiometric mixture in the presence of a high boiling antisolvent, comparatively a very efficient and cheaper method, yielded pure cocrystals. Cocrystals were well characterized by spectroscopic, thermoanalytical tools, X-ray diffraction, and microscopic techniques. A correlation of percentage of cocrystal formation with evaporation rate has been obtained through quantitative analysis using Raman spectrometry. An evaporation rate of <1 mL/min consistently produced pure cocrystal confirmed by Raman and powder X-ray diffraction analysis. Thermokinetic analysis suggests the cocrystal to be more stable than CL-20 with an energy of activation of 65 kcal/mol, higher than CL-20 but inferior to HMX. Significant augmentation in the values of k and A over CL-20 justified a faster decomposition rate. Enhanced insensitivity toward friction and impact forces and higher measured velocity of detonation indicate improved performance on incorporation into high explosive formulations.