Controllable Preparation and Thermochemical Properties of Ultrafine FOX-7 by Microfluidic Crystallization Strategy

The 1,1-diamino-2,2-dinitroethylene (FOX-7) has been adopted in high-energy explosives. To further improve the thermal safety and detonation performance of FOX-7, a microfluidic crystallization platform with a swirl-shaped chip was employed to prepare ultrafine FOX-7. Results show that the crystal structure of FOX-7 could be precisely controlled by adjusting the operational parameters of microfluidic. The microfluidic techniques prepared superfine FOX-7 exhibit a consistent smaller particle size, narrower particle size distribution, reduced crystal defects, and enhanced sphericity structure. On the other hand, the thermochemical properties of FOX-7 are also improved. The thermal decomposition temperature and critical thermal explosion temperature of ultrafine FOX-7 are increased by 24.6 and 22.1 °C, respectively. The thermal stability, energy release efficiency, and combustion of the microfluidic recrystallization method prepared FOX-7 are greatly improved. This research presents a secure, effective, and eco-friendly methodology for the preparation and manipulation of ultrafine FOX-7 crystals.