The influence of the number of fluorine atoms on the properties of energetic materials

Developing high-energy, low-sensitivity energetic materials has long been a primary goal in this field. This article explores fluorine-containing energetic materials based on Density Functional Theory (DFT) calculations. The study examines the impact of the number of fluorine atoms on the stability, energy, and crystal stacking of energetic materials. The results show that with the increase of the number of fluorine atoms, the stability of energetic materials gradually decreases. However, 1,5-difluoro-2,4-dinitrobenzene (A2) showed abnormal behavior and better stability compared to 1-fluoro-2,4-dinitrobenzene (A1). With increasing fluorine atoms, the detonation velocity and pressure of energetic materials initially rise before declining. Energetic materials have varying nitrogen and oxygen contents, and the number of fluorine atoms in compounds with the highest detonation velocity and pressure also varies. The intermolecular interactions facilitated by fluorine atoms in crystal stacking include intermolecular hydrogen bonding and halogen bonding. These results can provide a theoretical basis for the design of future energetic or fluorinated materials. Compound A2 was synthesized through a one-step nitration process using 1,3-difluorobenzene as the raw material, and its structure was confirmed. Compound A2 demonstrates consistent safety characteristics as anticipated: a thermal decomposition temperature exceeding 400 °C, impact sensitivity of 50 J, and friction sensitivity of 360 N. It has been established that there is potential for coordinating high energy content with safety features in energetic materials.