Preparation Of Explosive Co-crystals By Pneumatic Atomization And Molecular Dynamics Simulation

In order to meet the requirements of the development of insensitive high explosive,explosive co-crystal technology combines two or more different types of explosive molecules in the same crystal lattice through inter-molecular interactions to develop novel explosives with better overall performance.At present,the explosive co-crystal technology focuses on two aspects of theoretical simulation and experimental preparation.This article starts from these two aspects.On the one hand,the structural stability and co-crystal mechanism of binary co-crystal were analyzed by molecular dynamics simulation based on CL-20/TNT and CL-20/TNT/DNB co-crystal models,and the feasibility of ternary co-crystal formation was predicted and studied.On the other hand,the CL-20/TNT co-crystal was prepared by pneumatic atomization spray crystallization method.Based on this method,a pneumatic relative spray method was proposed,and the feasibility of the method was also verified by the preparation of the CL-20/TNT co-crystal.Finally,from the molecular design to the experimental preparation,an exploratory study of the ternary co-crystal was carried out to provide new ideas and new directions for co-crystal preparation.The main contents of this paper are as follows:(1)The MS software was used to build the CL-20/TNT co-crystal structure and the simulation was performed.The results show that: compared with CL-20 and TNT single components,the binding energy of CL-20/TNT co-crystal structure is relatively large,indicating that the co-crystal structure has better thermodynamic stability.There is more binding energy between TNT and CL-20(0 0 2)and(1 1-1)crystal faces,which is favorable for the formation of co-crystal.As the temperature increases,the thermal sensitivity becomes higher.The C—H…O hydrogen bonding between molecules in CL-20/TNT co-crystalexplosive promotes the formation of co-crystal structure.(2)The CL-20/TNT/DNB co-crystal structure,blend structure of CL-20/TNT and CL-20/DNB,CL-20/TNT/DNB blends structure were constructed respectively.By comparing and analyzing the calculated results,it can be concluded that compared to the other two models,the binding energy of the CL-20/TNT/DNB co-crystal structure is greater,indicating that the thermodynamic stability of the structure is better.The co-crystal system also has a higher cohesive energy density,reflecting that the molecular structure of this system is relatively stable.The hydrogen bonding between the H and O atoms in the co-crystal system is relatively strong,which can reduce the sensitivity.By calculating the mechanical parameters,it can be predicted that the co-crystal system has excellent mechanical properties.(3)The CL-20/TNT co-crystal was obtained by pneumatic atomization spray crystallization method.For co-crystal samples,they were characterized using scanning electron microscope and tested using differential thermal analysis,infrared spectroscopy,and X-ray diffraction.It is enough to prove that this method changed the structure and characteristics of the raw material components.On this basis,the influence of jetting temperature and charging ratio on the quality of the explosive co-crystal was investigated.Taking into account the yield and quality of the co-crystal samples,the ideal co-crystal process conditions were obtained.(4)In order to solve the problem of insufficient contact and uneven particle size in the spray crystallization process,the pneumatic relative spray method was proposed.The working principle and influencing factors of the experimental process were also analyzed.The CL-20/TNT co-crystal was prepared by this method,and the co-crystal samples were characterized and tested.The results show that this method is suitable for the preparation of co-crystal explosives,and has the advantages of small product size,narrow particle size distribution and safe operation.(5)Starting from the preparation of binary co-crystal,according to the screening principle of co-crystal precursors and crystallization solvents,using common components as a bridge,the possible combinations of ternary co-crystal explosives were sought for moleculardesign.The ternary co-crystal was experimentally studied by spray crystallization method.The explosive samples were obtained on the basis of suitable experimental conditions,and they were characterized and tested to analyze the experimental effects of the three explosives together,providing a new direction for the exploration and development of co-crystal explosives.