Synthesis Of End-Group Functional Fluorocarbon Oligomers And Preparation Of Fluorinated Energetic Polyurethanes

End-group functionalized fluorocarbon oligomers are a class of fluorinated oligomers with reactive functional groups that can be formed into fluorinated polymers by self-polymerization or copolymerization with other compounds.End-group functionalized fluorocarbon oligomers usually have good flowability,end-group activity and plasticity,and are easy to process,mold and cure,which are important raw materials for aerospace and semiconductor fields.In this thesis,end-iodide based perfluorinated oligomers with controllable molecular weight and copolymerization composition were prepared by the modulation method,further functionalized and modified to synthesize end-hydroxy fluorocarbon oligomers,and block polymerization reaction with azide polyether polyol(GAP)to prepare energy-containing polyurethanes containing fluorine elements and azide groups.The main research contents and results are as follows:(1)Synthesis study of iodine-capped perfluorinated oligomers.Iodine-capped perfluorinated oligomers were synthesized by iodine transfer polymerization reaction(ITP)using tetrafluoroethylene(TFE)and perfluoromethyl vinyl ether(PMVE)as reaction monomers and1,6-diiodoperfluorohexane as a modifier.The effects of initiation method,catalyst dosage,emulsifier concentration,monomer ratio and chain transfer agent dosage on the rate and yield of polymerization reaction,state,molecular weight and distribution of oligomers,and copolymerization composition were investigated.The molecular structure,molecular weight and distribution,and glass transition temperature of the oligomers were analyzed.The results showed that the yield of initiator initiation was much higher than that of thermal initiation,in which the best reaction conditions were achieved when the initiator concentration was 0.1wt% and the emulsifier concentration was 4 g/L.Adjusting the monomer feeding ratio could regulate the perfluoromethyl vinyl ether monomer units in the copolymerization composition between 8% and38mol%,and adjusting the amount of chain transfer agent could regulate the molecular weight range of oligomers between 1100 and 3500,and the molecular weight The apparent state is viscous liquid to paste,with certain fluidity.(2)Synthesis of end-group functionalized fluorocarbon oligomers and polyurethane prepolymers.The functionalized fluorocarbon oligomers with end groups of carboxyl,hydroxyl and acrylate groups were synthesized by addition reactions with acrylic acid,ethyl acrylate and 3-buten-1-ol,respectively,using end iodine-based perfluorinated oligomers as raw materials,and the effects of the type and amount of catalyst on the addition reactions were investigated,with yields up to78%.The end-hydroxy fluorocarbon oligomers,GAP and isocyanate were prepolymerized to synthesize polyurethane prepolymers with fluorine elements and azide groups.The effect of isocyanate index(R)on the molecular weight of the prepolymer was investigated.The molecular range of the prepolymer was between 8300-23600 and the molecular weight distribution was between 1.8 and 2.7.(3)Preparation and performance study of fluorinated energy-containing polyurethanes.One-step and pre-polymerization methods were used to prepare fluorinated energy-containing polyurethanes with controllable F and N content,and the curing process,mechanical properties,thermal properties and microscopic morphology of the cured products were studied.By adjusting the ratio of the two diols,the fluorine content could be adjusted from 6.1 to 20.8 wt% and the nitrogen content from 18.26 to 34.19 wt%.The mechanical properties of the cured products obtained by the pre-polymerization method are better,with a maximum elongation at break of 450%,a maximum tensile strength of 2.4 MPa,and a maximum peel strength of 21.6 N/mm with the variation of the hard segment content,and a more uniform distribution of microscopic morphology.