Structure Design,Performance Predictions And Controllable Synthesis Of Difluoro Amino Energetic Oligomer Plasticizers

With the upgrading of the solid propulsion system,its performance index gradually changes from the ingle energy index to the comprehensive performance index,especially the mechanical performance index.As an important component of propellant system,energetic plasticizer can not only effectively improve the energy,burning rate and range of propellant,but also improve the processability and low temperature mechanical properties of propellant.Therefore,the development of a new type of ideal energetic plasticizer has become one of the research hotspots of energetic materials.As one of the ideal energetic groups,the difluoroamino group has high energy,and the F element has oxidation property,which can improve the oxygen balance in the combustion process.On this basis,Aiming at the disadvantages of volatile and large mobility of small molecule energetic plasticizer at present,In this paper,two compounds containing difluoroamino groups,DFAMO and BDFAO,were used as monomers.80 kinds of new difluoroamino energetic oligomer plasticizers were designed.In this thesis,density functional theory(DFT)was used to study the geometric structure,electronic structure,heat of formation,density,thermal stability and detonation properties of a series of the designed target compounds;The glass-transition temperature of the designed target compounds was predicted by molecular dynamics simulation;selecting a structure with excellent comprehensive performance to synthesize,Optimizing the synthetic route and characterizing its structure.The main content consists of the following three parts:The heat of formation,thermal stability and detonation properties of the designed oligomers containing difluoroamino groups was studied at the DFT level with B3PW91/6-31G(d,p)basis set.Firstly,the heat of formation of the series of compounds was calculated via designed isodesmic reaction.Then,based on the calculated results of bond dissociation energy,the thermal stability of a series of compounds is compared and determined.Finally,the detonation velocity and detonation pressure of a series of compounds were predicted by calculated HOFs and densities.The effects of monomer,degree of polymerization,initiator and end group on the theoretical properties were analyzed.The glass transition temperature(T_g)of 80 kinds of difluoroamino energetic oligomer plasticizers designed were predicted by Using molecular dynamics theory and Materials Studio(MS)software.The specific volume-temperature relation curve was drawn based on the free volume theory and Origin software.The results show that the glass transition temperature increases with the increase of degree of polymerization.At the same time,the presence of nitrate group can decrease the glass transition temperature.PDFAMO was synthesized via cationic solution polymerization using TFBE as catalyst,glycerol as initiator and DCE as solvent.At the same time,the reaction conditions of PDFAMO were optimized.Its structure was characterized by NMR,IR and elemental analysis.The molecular weight determined by GPC was 812 and the PDI value was 1.12.NPD was synthesized via nitrification of terminal hydroxyl group of polymer PDFAMO using fuming nitric acid/acetic anhydride as nitration system and DCE as solvent.Its structure was characterized by NMR,IR and elemental analysis.Its molecular weight determined by GPC was 944 and the PDI value was 1.21.The glass transition temperature(T_g)of NPD was measured by DSC,the results showed that the T_g=-39.31?.