Single-step production and formulation of HMX nanocrystals

We assessed the feasibility of single-step production of nanocrystalline cyclotetramethylene tetranitramine (HMX)-based composite granules by spray drying. Acetone solution of HMX and a polymeric binder was spray-dried using a commercially available spray dryer equipped with a compressed gas nozzle. During spray drying both ingredients precipitated simultaneously under high degrees of supersaturation, conditions necessary for small crystal size. The product was characterized using focused ion beam coupled scanning electron microscopy (FIB-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and high-performance liquid chromatography (HPLC). We found that similar to 1 mu m composite granules were formed comprised of sub-100 nm HMX crystals dispersed in the binder matrix. gamma and delta polymorphs of HMX were found in the product. Due to its simplicity, the spray drying method lends itself to facile production of bulk quantities of a variety of nanocomposite energetics. (C) 2012 Elsevier B.V. All rights reserved.