Effects of carboxymethylcellulose sodium on the morphology and properties of TKX-50, an insensitive high-energy explosive

Dihydroxylammonium 5,5ʹ-bistetrazole-1,1ʹ-diolate (TKX-50) is an energetic ionic salt with excellent properties of low mechanical sensitivity, environment-friendliness, and low toxicity. It meets the requirement of high insensitivity for military high-energy explosives. However, the poor crystal habit of TKX-50 in most solvents, as well as its poor adhesive ability with conventional binders, has limited its application. In the present work, we report a novel strategy to improve the morphology and surface property of TKX-50 using an environmentally friendly anionic polyelectrolyte, carboxymethylcellulose sodium (CMC), by the anti-solvent method. The scanning electron microscope analysis indicates that the morphology of TKX-50 was greatly altered in the presence of CMC, resulting in TKX-50 granules with low aspect ratios. Molecular dynamics simulation was conducted to explore the mechanism of such morphological change. It was found that the combined action of ethanol and CMC promoted the growth of (110) and (011), while the (020) still dominated the crystal growth, resulting in the low aspect ratio of TKX-50. The effects of CMC coating on the particle size of TKX-50 and the interaction between CMC and TKX-50 were investigated with the focused beam reflectance measurement and particle video microscope. Further characterization suggested that the highest coating efficiency (R) could be obtained at the CMC content of 4% with which granular TKX-50 crystals were produced. The non-isothermal kinetic study revealed that the CMC coating also improved the thermal stability of TKX-50. Our work has provided a novel method to improve the properties of TKX-50 for its practical application.