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 ~ 1 μm composite granules were formed comprised of sub-100 nm HMX crystals dispersed in the binder matrix. γ and δ 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.

Graphical abstractSingle-step production of cyclotetramethylene tetranitramine (HMX)-based nanocomposite granules was demonstrated by spray drying. Characterizations show that sub-100 nm HMX nanocrystals were produced and formed ~ 1 μm nanocomposite granules along with a polymer binder. This simple single-step method may serve as a cost-effective strategy to prepare and formulate nanocrystalline energetic materials.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Cyclotetramethylene tetranitramine (HMX) nanocrystals were produced and formulated into granules. ► This was demonstrated by spray drying of dissolved HMX and binder in acetone. ► The product was characterized by SEM, TEM, XRD and HPLC. ► This work demonstrated the broader application of spray drying for nanoenergetic materials.