Electrospray Crystallization for High-Quality Submicron-Sized Crystals

Nano‐ and submicron‐sized crystals are too small to contain inclusions and are, therefore, expected to have a higher internal quality compared to conventionally sized particles (several tens to hundreds of microns). Using electrospray crystallization, nano‐ and submicron‐sized crystals can be easily produced. With the aid of electrospray crystallization, a mist of ultrafine solution droplets is generated and subsequent solvent evaporation leads to crystallization of submicron‐sized crystals. Using cyclotrimethylene trinitramine (RDX) solutions in acetone, the conditions for a stable and continuous jet were established. At relatively small nozzle diameters and relatively low potential differences, hollow spheres of RDX crystals were observed. At a higher nozzle diameter and potential difference and in the region of a continuous jet, RDX crystals with an average size of around 400 nm could be produced. In order to test the quality of the submicron‐sized energetic material, impact and friction sensitivity tests were carried out. The test results indicate that the submicron‐sized product had reduced friction sensitivity, indicating a higher internal quality of the crystalline product. Electrospray crystallization is proposed as a method for creating high‐quality submicron‐sized crystals of the energetic material cyclotrimethylene trinitramine (RDX). The friction sensitivity of the obtained unagglomerated submicron‐sized crystals was lower than that of conventional RDX, indicating that they have a better internal quality.