Preparation And Properties Of Graphene/Polyimide Composite

Polyimide is a kind of polymer with imide bond(-CO-NH-CO-)on the main chain.Because of its unique heteroaromatic structure,it has excellent comprehensive properties.It is suitable for a wide range of temperature,excel ent mechanical properties,chemical stability and dielectric properties.So polyimide is widely used in electric vehicles,aerospace and other fields.At the same time,in order to meet the application of polyimide in some specific conditions,it is usually modified.A large number of studies show that graphene has excellent chemical and physical properties due to its unique two-dimensional network structure.It can effectively improve the comprehensive properties of polyimide.However,due to the?-?stacking between graphene and strong van der Waals force,graphene cannot be well dispersed in polyimide.In this paper,the preparation and properties of modified graphene and polyimide composite materials are studied and some novel modified preparation methods are proposed,which make it have a wide application prospect in electric vehicles,aerospace and other aspects.The specific research contents are as follows:(1)Through electrophilic substitution reaction,L-phenylalanine reacts only with sp~2 hybridized CH bond at the edge of graphene to prepare edge aminated graphene,which is capped with siloxane-terminated polyimide Blend to prepare composite materials.The dispersibility of graphene in polyimide is greatly improved,thereby improving the thermal performance,friction and wear performance of composite materials.It has wide application prospects in lubrication and wear resistance.(2)Catecholated graphene(G-Cat)was prepared by 1,3 dipolar cycloaddition reaction.This method can ensure the integrity of the graphene sheet during the reaction as much as possible,and the grafting of hydroxyl groups can enhance the interface bonding strength of graphene and the polymer matrix and enhance its dispersion.The mechanical properties and thermal stability of the prepared graphene/polyimide composite materials have been improved.It has good applications in some extreme environments.(3)Grafted cage polyhedral oligomeric silsesquioxane(POSS)onto graphene.Using the synergy between graphene and POSS,the prepared composite material can greatly improve the polyimide's antigenic oxygen corrosion performance.Effectively inhibit the erosion of the composite material by atomic oxygen.It has wide application prospects in aerospace.