One-step rapid preparation of CL-20/TNT co-crystal assembly and spheroidized coating based on droplet microfluidic technology

Energetic materials pose challenges in preparation and handling due to their contradictory properties of high-energy and low-sensitivity. The emergence of co-crystal explosives is a new opportunity to change this situation. If the co-crystal explosive is coated into spherical particles with uniform particle size distribution, this contradiction can be further reduced. Therefore, binder-coated hexanitrohexaazaisowurtzitane/2,4,6-trinitrotoluene (CL-20/TNT) co-crystal microspheres were prepared by droplet microfluidic technology in this work. The coating effects of different binder formulations of nitrocellulose (NC) and NC/fluorine rubber (F2604) on the co-crystal spheres were studied. The scanning electron microscopy (SEM) results showed that the use of droplet microfluidic technology with the above binders can provide co-crystal microspheres with regular spherical morphology, uniform particle size distribution and good dispersion. X-ray diffraction (XRD), fourier-transform infrared (FT-IR), differential scanning calorimetry (DSC) and thermo-gravimetric (TG) methods were employed to compare the properties of the co-crystal microspheres, raw material and pure co-crystal. The formation of CL-20/TNT co-crystal in the microspheres was confirmed, and the co-crystal microspheres exhibited better thermal stability than the raw material and pure co-crystal. In addition, the mechanical sensitivity and combustion performance of the co-crystal microspheres were further studied. The results showed that the co-crystal microspheres were more insensitive than CL-20 and pure co-crystal, and displayed excellent self-sustained combustion performance and theoretical detonation performance. This study provides a new method for the fast, simple and one-step preparation of CL-20/TNT co-crystal microspheres, with binder coating, uniform particle size distribution, and excellent performance level.(c) 2022 China Ordnance Society. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/).