Study On Hydrophobic Modification Of Polyimide Films And Their Properties

In the study of inertial confinement fusion(ICF),polyimide films with excellent mechanical properties are usually used as column cavity sealing membranes to achieve isolation between the column cavity and the vacuum target chamber.In recent years,with the development of ICF research,physical experiments are no longer confined to normal temperature,but also need to be performed in a low temperature or ultra-low temperature environment.However,low-temperature physical experiments have found that when the target is in a high-vacuum,ultra-low temperature environment,the condensation phenomenon of the contaminants on the column cavity sealing membrane will seriously damage the laser transmission efficiency,affect the development of physical experiments,and has an important impact on the accuracy of the experimental data.Therefore,the development of self-cleaning film will be able to fundamentally solve the problem of condensation on the surface of the sealing film,and providing a possible solution for physical experiments.In this dissertation,two surface modification methods of polyimide film were developed,which effectively controlled the surface wettability of the film.In the first part,inorganic materials such as CNTs,POSS,and FSi O2 were used for doping.Through a simple solution mixing method,the nanoparticles were uniformly mixed into a polyamic acid solution,and finally a polyimide film was prepared.Due to the introduction of nanoparticles,the surface microstructure of the film was changed,which increased the contact angle of the film to water.In the second part,the polyimide film modified by plasma etching and surface grafting modification.Plasma etching is one of the most important methods for the surface modification of films.Through plasma treatment,the surface roughness of the film can be effectively increased,and an active group capable of further graft modification can be formed on the surface of the film after etching,and a low surface energy can be introduced on the surface of the film by a graft modification method.Through grafting modification,themolecular structure with low surface energy can be introduced on the surface of the films.While changing the microstructure of the film surface,it also changed the chemical composition of the film surface,which made the hydrophobicity and oil repellent property of the film have been greatly improved.The research shows that changing the microstructure and surface chemical composition of materials on the surface has greater influence on the wettability of materials.This work provides a good idea for future research.