Recent advances on the crystallization engineering of energetic materials

The safety properties and desirable detonation performance of energetic materials (EMs) are mutually exclusive, therefore, various strategies including the coating, doping, crystallization, and co-crystallization, are applied to achieve high-energy insensitive explosives with well-balanced energy and safety level. Among these strategies, the crystallization is the most commonly method owing to its low cost and facile process, through which the tuning of the particle size and morphology, adjust sensitivity of EMs by tailoring the processes conditions. As the control of the crystal particle size is difficult, the ultrasound and electrospray are introduced, and by use of the spray drying or spray-assisted electrospray methods, the spherical RDX, HMX, and CL-20 crystals with less defects is obtained. Moreover, the perfect spherical crystals are gained without agglomeration through employing polymeric additives in the crystallization process. In general, the crystallization with spray drying, electrospray, and ultrasound-assisted solvent/antisolvent are the optimal crystals preparation methods. The nano-crystals with narrow particle size distribution are less sensitive to external stimuli than irregular microcrystals, and defects are associated with hot spots, the safety and energy performance of EMs could be well balanced by crystallization.