Cocrystal Desensitization And Simulation Study Of High Energy CL-20 Explosive

The application of cocrystal technology in the field of energetic materials provides an effective way to solve the contradiction between energy and sensitivity of energetic materials.At the same time,co-crystallization can also adjust some of the physical and chemical properties of the original material,such as hygroscopicity,solubility,melting point and so on.Hexanitrohexaazaisowurtzitane(CL-20)is receiving more and more attention due to its extremely high energy levels.The Cocrystal materials surrounding CL-20 explosive are also being developed,reflecting the characteristics of high-energy insensitive high-quality explosive.In this paper,the preparation and simulation of high-energy CL-20 cocrystal explosives are carried out.The main research contents and results are as follows:(1)The computer simulation was applied to the study of the cocrystal mechanism,and the internal interaction of the cocrystal explosive was explored from a micro perspective.The surface electrostatic potential energy of CL-20 and the ligand material was analyzed by Materials Studio 5.0 software,and the results showed that the mutual attraction of electrostatic potential between groups helped form non-covalent bonding forces between molecules.At the same time,the energy differences between the raw materials and the cocrystal system were analyzed.The results showed that the energy level of the cocrystal was lower,and the co-crystallization is a thermodynamically favorable process.Finally,Crystal Explorer 3.1 software was used to analyze the intermolecular interaction types of a series of CL-20 cocrystal explosives and distinguished the areas of action,which laid the groundwork for the subsequent development of CL-20 cocrystal explosives.(2)Combining"Nano Desensitization"and"Cocrystal Desensitization",by analogy with the cocrystal explosive prepared by the solvent evaporation method,the wet mechanical ball milling method had successfully prepared CL-20/TNT cocrystal explosive.with an average particle size of 115.9 nm.The sensitivity test showed that compared with CL-20 and CL-20/TNT mixture,the characteristic drop height of CL-20/TNT cocrystal explosive increases by26 cm and 20.8 cm respectively,greatly reduces the sensitivity of CL-20,and effectively improves the safety performance.This can be explained by the formation of hydrogen bonds between-NO₂ in CL-20 and-CH₃ in TNT,which enhances the stability of the crystal structure.Experiments had proved that wet mechanical ball milling can prepare nano-scale cocrystal explosives in large quantities,and provides an effective method for industrialized large-scale preparation of cocrystal explosives.(3)The"energetic ion salt"was introduced into the preparation of CL-20 cocrystal explosive.CL-20/TKX-50 cocrystal explosive was successfully prepared by solvent-nonsolvent method.The characteristic drop height(H₅₀)of CL-20/TKX-50 cocrystal explosive is 34 cm,lower than that of TKX-50,but significantly higher than that of CL-20 and?-HMX,and also higher than that of mechanical mixture of CL-20 and TKX-50,effectively reducing the sensitivity of CL-20.The decrease of sensitivity was supposed to be due to the formation of hydrogen bond between-NO₂ in CL-20 and-NH₃⁺in TKX-50,which enhances the stability of the system structure.This indicates that energetic ionic salts can be used as high-quality ligands for CL-20 cocrystal explosives.(4)Based on the computer simulation and the analysis of the existing CL-20 series of cocrystal explosives,it was proposed that the symmetrical cyclic compounds with electron donor groups can be used as effective ligands for the preparation of CL-20 cocrystal explosives.2,6-Diaminotoluene,pyrazine,and 2,3,5,6-tetramethylpyrazine,which have electron-donating groups and have good symmetry,were selected for co-crystallization experiments with CL-20.Finally,CL-20/pyrazine and CL-20/2,3,5,6-tetramethylpyrazine cocrystal explosives were successfully prepared,which effectively reduced the sensitivity of CL-20.This provides new ideas for the development of more CL-20 cocrystal explosives.