Strategies For Achieving Balance Between Performance And Stability Of Energetic Materials

The detonation performance,stability and safety of energetic materials are of critical importance because they are decisive to the damage power,stockpile,and combat survivability of modern weapons,and are also decisive to national life and property safety during the civil engineering development process.Although the extremely high hazard and cost of the experimental research of energetic materials and the long-term lifecycle of their characterization,manufacturing,testing and inspection could be the excuses for the slow development of energetic materials,one more important reason preventing energetic materials from fast development is the contradiction between high detonation performance and high stability of energetic materials.High detonation performance of energetic materials relies on the large energy difference between the reactants and the reaction products,while high stability of energetic materials needs a high energy barrier to prevent the initiation of such reactions.The long-standing performance-stability contradiction issue of energetic materials is challenging chemists due to the extremely intricate causality.Subjected to significant demands of national defense and civil engineering,this thesis conducted systematic research on the structural stability,physicochemical parameters,and detonation performance of high-energy-density yet high-stability explosives,and presented quantitative strategies for balancing performance and sensitivity of energetic materials.The specific content can be summarized in the following aspects:（1）Through the systematic research of the physicochemical properties of highly stable energetic materials such as HNS,TATB,HMX,CL-20,and DATB,it is found that increasing the hydrogen bond content and hydrogen bond strength can improve the crystal structure stability of energetic materials,and the construction of bridged bond and non-planar heterocyclic ring/cage-like molecular structure can improve the thermal stability;By conducting quantum mechanical simulations for N₃C₂H₂,N₄C₁H₁,N₅^-and N₄^2-,the competitive mechanisms of basicity and dual-aromaticity in heterocyclic anions have been confirmed.It has been found that heterocyclic anions violate the law of acid-base neutralization reaction under high acidity conditions and do not undergo protonation,but enhance dual-aromaticity by intermolecular hydrogen bonding,thus significantly enhancing the stability of cyclic structure,providing theoretical basis for the preparation of new cyclic high/all-nitrogen ions.（2）Through the systematic research of the physicochemical properties of high performance energetic materials such as CL-20,HMX,HNB,BTNENA and RDX,it is confirmed that the nitrogen density,material density and oxygen balance are the most important physicochemical characteristics that affect the detonation performance,and the mechanism of physicochemical characteristics such as crystal stacking mode,molecular backbone,and functional groups on detonation performance is found.（3）Through high-throughput quantum mechanical calculations and machine studies of energetic materials,it is found that molecular mass,bridged bond and non-planar heterocyclic/cage-like molecular structure can simultaneously promote detonation performance and stability of energetic materials.It is revealed that oxygen balance,hydrogen bonding and hydrogen bonding strength are the most important physicochemical characteristics that cause the contradiction between high performance and high stability of energetic materials.A quantitative strategy for balancing the performance and stability of energetic materials is proposed;Through the principle of maximum hydrogen bond and molecular dynamics simulation,stable molecular clusters of eutectic TATB/CL-20 and new eutectic tetrazole energy content Co N₄ are constructed,respectively.Symmetry is introduced into the molecular clusters of Co N₄by traversing each crystal group using the minimum energy principle,and the theoretical crystal structure is constructed.The final stable crystal structure is used to predict detonation performance and stability,and the results show that the Co N₄ crystal has comparable performance with CL-20 and HMX as well as fair stability.