A Novel Spherulitic Self-Assembly Strategy for Organic Explosives: Modifying the Hydrogen Bonds by Polymeric Additives in Emulsion Crystallization

A novel strategy to prepare spherical crystals of 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) has been developed by introducing polymeric additives into the antisolvent emulsion crystallization. The spherical crystals are induced by modifying the intermolecular hydrogen bonds network of LLM-105. The results show that the concentration of polyvinylpyrrolidone (PVP), which acts as a polymeric additive, is a crucial factor to get quite different morphologies of LLM-105 crystal products. X-like shaped crystals have been produced in the absence of PVP. In contrast, spherical crystals have been obtained in the presence of PVP. Importantly, LLM-105 spherulites with a mean particle size of 78.0 μm can be obtained by adding a proper amount of PVP, which has a narrow size distribution (CV = 31.2). In addition, time-resolved morphological evolution processes of X-like shaped and spherical crystals have been performed. Meanwhile, 1H NMR experiments also have been conducted to understand the intermolecular hydro...