Study On Morphology Control And Crystal Structure Evolution Of TKX-50 Induced By Solvent

Energetic ion salts have become a research hotspot in various countries due to a series of advantages such as lower toxicity,higher enthalpy of formation and lower vapor pressure.Dihydroxylammonium 5,5'-bistetrazole-1,1'-diolate salt is a new type of high-energy,low-sensitivity energetic ion salt,referred to as TKX-50.The theoretical test density,detonation speed and detonation pressure of TKX-50 are 1.918 g cm^-33 and 9698 m s^-1,42Gpa,respectively,which can be a substitute for RDX and have a broad application prospect in propellant.This work aimed at the problems of low crystal quality and poor morphology existing in TKX-50,studied the factors affecting its crystallization behavior,and prepared the crystals with regular crystal morphology and excellent performance.At the same time,studied the structure evolution of TKX-50 in different solvent crystallization and tested the performance of the obtained new structure,which provided a strong experimental and theoretical basis for later application.The specific work of this article is as follows:?1?Select different crystallization methods such as cooling crystallization,evaporation crystallization,solvent-antisolvent etc.for different solvent systems to recrystallize Dihydroxylammonium 5,5'-bistetrazole-1,1'-diolate salt.The results showed that different types of solvents and crystallization methods had a great influence on the morphology of TKX-50 crystals.After recrystallization in different solvents,crystal shapes such as block-like,needle-like and short stick-like and flaky-like could be obtained.?2?Using Material Studio simulation software,predicted the crystal morphology of TKX-50 in single solvent water,dimethyl sulfoxide?DMSO?and binary solvent such as water/dimethyl sulfoxide,ethyl acetate/dimethyl sulfoxide,ethanol/dimethyl sulfoxide,dichloromethane/dimethyl sulfoxide,Acetone/methanol,acetone/ethyl acetate,acetone/isopropanol,acetone/dichloromethane,acetone/toluene,also in additives sodium laurylsulfonate,sodium dodecylbenzenesulfonate and Tween 20 system.The prediction results were in good agreement with the experimental results.?3?The performance of the block-like,needle-like and short stick-like crystals obtained in the three additive systems of sodium laurylsulfonate,sodium dodecylbenzenesulfonate and Tween 20 were tested.The results showed that the internal structure of three crystal morphologies was not changed,but the density and thermal stability were improved and superior to the raw materials,and had different degrees of impact on friction sensitivity and impact sensitivity.In particular,the short stick-like shape obtained in Tween 20 had the best thermal stability and the most complete internal structure with the density of 1.8887 g·cm^-3,H₅₀>100 cm and friction sensitivity of 0%,and the needle-like crystal morphology with the worst performance.The results indicated that the performance of the crystal had a great relationship with the morphology.?4?The TKX-50 was crystallized in 7 solvents through different solvent screening methods to obtain four solids and three single crystal structures[NH₂?CH₃?₂⁺][BTO^-]obtained in DMAC solvent,[NH₂?CH₃CH₂?₂⁺]₂[BTO^2-]obtained in DEF solvent and[NHOH?CH₃CCH₃?⁺][BTO^-]·H₂O obtained in acetone/methanol?volume ratio 1:1?,respectively.The crystal structure of the three crystals was determined by X single crystal ray diffraction method,and the energy properties of the three single crystal structures were calculated by EXPLO5 software.