Molecular Design And Synthesis Of Boron-based Energetic Compounds

Due to the high calorific value,boron（B）can improve the explosive power,which make energetic materials based boron have good application prospects in initiating explosive and propellants.In the concept of"subversive energetic materials"proposed by the United States in 2014,in addition to the energetic materials such as metal hydrogen and total nitrogen compounds,the boron based energetic materials with high tension bond energy release characteristics are also included in the key development direction,pushing the boron based energetic materials to the research vent.However,the domestic research on boron based energetic materials is still in the initial stage,and the research on their energy release characteristics and their structure-activity relationship has not been widely carried out.In this paper,molecular design,performance prediction and preparation path are studied to provide new ideas and methods for the development of new boron based energetic materials.The main research work and conclusions are as follows:1.The structure design and performance prediction of borate ester energetic compounds are studied.Firstly,the structural advantages of borate ester energetic compounds are analyzed,and then the feasibility of synthesis is analyzed.Finally,based on the transesterification reaction and hydroxylated tetrazolium energetic compounds as ligands,10tetrazolium borate ester energetic compounds are designed.The density,heat of formation,impact sensitivity and detonation performance are calculated theoretically.The results show that:（1）the introduction of fluorine atoms can greatly increase the molecular density,and the density values of the designed fluoroborate ester energetic compounds are above 2.0 g/cm³;（2）The contribution to the molecular density value is-OCF₃>-CF₃>-NF₂>-CF（NO₂）₂.Although-OCF₃group contributes greatly to the density,its contribution to detonation performance is not as good as-NF₂group;（3）The detonation velocity values of 10 kinds of borate ester energetic compounds are all above 8000m/s.2.The structure design and performance prediction of cycloborane compounds are studied.The purpose is to explore the application prospect of cycloboroxyalkanes in the field of energetic materials,and to compare the differences between cycloborazones（boroxazines）and cycloborazones（boroxazines）in terms of energetic properties.The theoretical calculations of 7 kinds of energetic compounds of cycloboroxyalkanes and 3 kinds of cycloboroxyalkanes（borazines）are carried out.The results show that:（1）The density of cycloborane compounds is higher than that of cycloborazone（borazine）compounds,but the heat of formation is lower than that of cycloborazone（borazine）compounds,and the detonation velocity,detonation pressure and sensitivity of cycloborazone（borazine）energetic compounds are better than that of cycloborazone energetic compounds;（2）The predicted detonation performance of seven kinds of cycloboroxyalkane compounds is not very good,but in view of the high bond energy of B-O bond and the actual energy content characteristics of cycloboroxyalkane energetic compounds,it is necessary to further verify through experiments.3.The structure design and performance prediction of boron nitrogen heterocyclic energetic compounds are studied.Based on the basic idea of dipyrazole borane energetic transformation,15 kinds of diazole diborane compounds are designed,including 6 kinds of dipyrazole diborane energetic compounds,5 kinds of ditriazole diborane energetic compounds and 4 kinds of dipyrazole diboroflurane energetic compounds.The results show that:（1）The heat of formation of diazole diborane compounds is positive,while that of diazole diboroflurane compounds is negative,indicating that the introduction of B-F bond will reduce the heat of formation of compounds;The heat of formation of ditriazolyl diboranes is higher than that of dipyrazole diboranes;（2）The low detonation heat of boron fluoride energetic compounds indicates that the introduction of F atoms will reduce the heat of formation,but will increase the density,which has greater advantages in detonation velocity and detonation pressure.4.The structure design and performance prediction of ionic boron based energetic compounds are studied.With triazole,pyrazole and tetrazole energetic compounds as ligands,10 kinds of one to four coordinated anionic structures with boron atom as the center and B-N bond as the connection are designed.55 kinds of ionic energetic compounds are formed by combining with 5 kinds of cations such as ammonium,hydrazine,hydroxylamine,guanidine and aminoguanidine.Based on the rational design of anionic isobond reaction,the detonation properties of 55 ionic energetic chemical detonations are predicted.The calculation shows that 55 ionic energetic compounds all have excellent detonation velocity,detonation heat,detonation pressure and specific impulse value.The maximum detonation velocity is10093m/s,the maximum detonation heat value is 6935k J/kg,the maximum detonation pressure value is 54.98GPa,and the specific impulse value is 2055-2636N·s/kg;Compared with common energetic oxidants,the specific impulse values of hydrazine salts formed by anions A4,B1,B3,C1and C2 are greater than the specific impulse values of nitrohydrazine（HNF）（2493.12N·s/kg）,and the specific impulse values of ammonium salts corresponding to three series of anions A,B and C are greater than the specific impulse values of ammonium dinitrate（ADN）（2003.17 N·s/kg）.5.Some ionic boron based energetic compounds are synthesized.With 3-nitro-1,2,4-triazole as ligand,six kinds of boron based energetic ion salts are successfully synthesized through the high temperature reaction of alkali metal borohydride salt to form a two coordinated energetic anion with boron atom as the center and 3-nitro-1,2,4-triazole as ligand,and then reacted with sulfate containing ammonium,hydrazine,hydroxylamine,guanidine,aminoguanidine and other cations respectively.The single crystals of three kinds of boron based energetic ion salts are cultured and their crystal structures were analyzed.Compared with common energetic oxidants,the thermal stability of the six ionic salts is better than that of ammonium dinitrate（ADN）;The theoretical specific impulse values are greater than AP and ADN;Except potassium bis（3-nitro-1,2,4-triazolyl）borate,the other five energetic ionic salts have low mechanical sensitivity.It can be seen that these ionic salts can be used as high-energy oxidants in propellants.