Nanoscale 2CL-20·HMX high explosive cocrystal synthesized by bead milling

Abstract

Energetic nanoscale 2CL-20·HMX, a cocrystal of CL-20 and HMX in a 2 : 1 molar ratio, was prepared by a novel method of bead milling an aqueous suspension of ε-CL-20 and β-HMX. The conversion of the coformers to the cocrystal form was monitored by powder X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis of specimens sampled at various milling times. Complete conversion to the cocrystal form was achieved by 60 minutes of milling. Rounded 2CL-20·HMX cocrystal particles with a mean size below 200 nm were produced. A mechanism for the conversion of the coformers to the cocrystalline form is postulated based on the experimental results. As an inherently safe manufacturing method, the aqueous bead milling process has great potential in advancing cocrystal research and applications in the field of energetic materials.