Theoretical Studies On The Structures And Properties Of Novel Cyclic Fluorides

Fluorinated organic compounds are a kind of compounds with wide applications.Due to the strong oxidizing property and large density of the F atom,introduction of F atoms into the traditional CHON energetic compounds can increase their densities and oxygen balances.Therefore,organic fluorides have broad application prospects in energetic materials,and it is important to study their structures and properties.In this thesis,the molecular structures,thermodynamic properties,detonation performance and stability of cyclic organic fluorides are systematically studied using the density functional theory method,and some cyclic fluorides with good performance are recommended to conduct synthesis experiments.The main contents are as follows:1.Using three density functional theory methods?B3LYP,B3PW91 and M06-2X?and six basis sets,the theoretical densities of 35 cyclic fluorides are calculated by Monte Carlo statistical method in Chapter 2.Based on the geometries optimized at the B3PW91/6-31G*level,the theoretical densities are also predicted by the electrostatic potential parameter method.The theoretical densities are compared with the experimental crystal densities.It is found that the results of the M06-2X/6-31G*method exist the best correlation with the experimental values.The crystal densities of the cyclic fluorides can be conveniently and accurately predicted from the theoretical densities using the fitted equation.2.The molecular structures,thermodynamic properties,and detonation properties of 35cyclic fluorides are theoretically studied in Chapter 3.Compared with the results of Cheetah and EXPLO5,the modified K-J equation can accurately predict the detonation performance of cyclic fluorides.3.The cyclic fluorides?9,10,12,16,23,26,29,34?with relatively good detonation performance in previous chapter are selected and modified structurally in Chapter 4.The thermodynamic properties and detonation properties are studied at the M06-2X/6-31G*level.Introduction of groups such as-SF₅,-NF₂,-NO₂,-C?NO₂?₂NF₂,-C?NO₂?₂SF₅ moderately will improve the detonation performance of the cyclic fluorides.4.21 difluoroaminonitrobenzene derivatives are designed in Chapter 5.Using the M06-2X/6-31G*method,the molecular structures,thermodynamic properties,detonation properties and thermal stability are systematically studied.The Mulliken population of the N-F bond is the smallest,which indicates that the N-F bond might be the weakest and the trigger bond in thermolysis processes.The density,detonation velocity,detonation pressure,and specific impact all increase with the increasing number of the-NO₂ group and the-NF₂group.Introduction of the-NO₂ group and the-NF₂ group appropriately is beneficial to improvement of the detonation performance of compounds.According to the energetic properties and the stability,compounds 77,78,79,80,88,89 and 90 are the potential targets of high energy density compounds.