Preparation and characterization of core–shell structured FOX-7/F2602 PBX with improved thermal stability and reduced sensitivity

To improve thermal stability and security of energetic materials, the core–shell structured FOX-7 (1,1-diamino-2,2-dinitroethylene)/F2602 (fluoroelastomer) PBX (polymer bonded explosive) was prepared from recrystallized FOX-7 by a spray drying strategy. The morphology and crystal form of the recrystallized FOX-7 were retained, and the mean particle size of the FOX-7/F2602 PBX was apparently reduced from 39.72 µm of raw FOX-7 to 1.50 µm. SEM, TEM, and XPS analysis showed that F2602 was deposited on the surface of FOX-7 to form a core–shell structured composite. The formation mechanism of the core–shell composite was proposed. Compared with the recrystallized FOX-7 grains, the prepared FOX-7/F2602 PBX had higher apparent Ea and Tb, which signifies improved thermal stability and thermal safety. The impact sensitivity test showed that the critical height value (H50) of the FOX-7/F2602 composite had remarkable enhancement, indicating better mechanical security. This work provides a simple and effective method to prepare the core–shell structured energetic composite with enhanced safety performance.