Study On The Synthesis And Stability Of Poly Nitrogen Energetic Compounds

Poly-nitrogen compounds have been developed rapidly in recent years as a new kind of energetic materials.They possess the characteristics of high nitrogen content,high positive heat of formation and eco-friendly products.They have been extensively used in high-energy insensitive explosives,low characteristic signal propellants and gas generators.However,due to the instability of poly-nitrogen compounds,the further researches have been restricted seriously.Therefore,the new research branches of energetic materials have been expanded into exploring the law of stability of poly-nitrogen compounds,searching new methods of stabilizing poly-nitrogen compounds.According to the idea of introducing extra forces to poly-nitrogen compound,a series of poly-nitrogen composite systems have been designed and synthesized.Their thermodynamic stabilities have been investigated by combination of theoretic and experimental methods.The synthesis and performaces of the graphene oxide?GO?doped 3D energetic metal organic framework?MOF-Cu?was investigated.TEM and XPS shows that the MOF-Cu can be connected with GO by the interaction between the Cu²⁺in MOF-Cu and the oxide-containing groups on GO.GO can increase the decomposition temperature of the MOF-Cu from 243?to 270?.Due to the thermal conductivity of GO,the decomposition of MOF-Cu is catalized,and the secondary decomposition is vanished.Moreover,both impact and electrostatic sensitivities of the MOF-Cu can be decreased by introducing GO,the more the GO,the low the sensitivities.The super molecules of nitroform,3-nitropyrazole,3,5-dinitro-1,2,4-triazole,5-nitro-2H-tetrazole and?-cyclodextrin were synthized,and their stabilities were investigated.¹H NMR shows that C-H···O hydrogen bonding is the main force of the formation of super molecules.DSC results shows that the super molecule of3-nitropyrazole and?-cyclodextrin has no melting point,the decomposition temperature of nitroform is increased from 17?to 167.1?.4-Dimethylaminophenylpentazole,4-methoxylphenylpentazoleand4-hydroxyphenylpentazoleweresynthesized.Thesinglecrystalof4-dimethylaminophenylpentazole was obtained,the phenyl and pentazole are not in one plane,?-?and C-H···N interactions are formed between each molecule.The thermodynamic stability of 4-dimethylaminophenylpentazole was investigated by combining FTIR and Raman spectra,the results shows that it decomposes violently at56?,and the rate of decomposition can be accelerated by temperature increasing.The decomposition mechanism of aryl pentazole was discussed,and the influence factors of the stability were elaborated.The stability of pentazole can be enhanced by electrophobic groups in p position,?-?and C-H···N interactions also have positive effect on increasing the stability.According to the?interaction,the composite systems of aryl pentazole?Ph-N₅?,pentazolate anion?N₅^-?and carbon nanotubes?CNTs?were investigated by computational analysis,thier thermodynamic stability and decomposition mechanism were investigated.Ph-N₅ and N₅^-can be adsorbed on the surface or in the cavity of CNTs,the former one is preferred.?7,7?CNT can capture Ph-N₅ in the cavity with the highest adsorption energy 44 kcal·mol^-1.The dissociation energy of N₅^-is increased from-8.0 kcal·mol^-1 to-39.6 kcal·mol^-1 by combining with CNTs.The composite system can't enhance thermodynamic stability of Ph-N₅ and N₅^-,but can protect them from photodecomposition and electric charges.The super molecule of 4-dimethylaminophenylpentazole and?-cyclodextrin was designed and synthesized.¹H NMR shows that 4-dimethylaminophenylpentazole can be capsulating in the cavity of?-cyclodextrin.DSC result shows that the decomposition temperature of 4-dimethylaminophenylpentazole is increased from 56?to 89?.In summary,many kinds of poly-nitrogen under different extra forces were designed and synthesized in this dissertation.Through a series of characterization methods,the structure characteristics and the performance characteristics of the new systems were investigated,and the influence factors of thermodynamic stability were revealed by exploring the properties both by experimental and theoretical methods.The investigation in this dissertation will provide new ideas for the further researches on poly-nitrogen compounds and play an important role in the development of poly-nitrogen and full nitrogen energetic materials.