▎ 摘　　要

NOVELTY - High barrier graphene composite polyimide film comprises a three-layer structure sequentially from top to bottom comprising polyimide (PI) film layer, graphene layer and PI film layer. USE - The PI film is useful in mobile phone electronic product, chemical medical device, other fields, photoelectron and aviation field. ADVANTAGE - The PI film: has greatly improved water resistance and excellent water-blocking performance; and widens the application field. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for preparing the polyimide film, comprising (a) using dianhydride and diamine monomer for mixing in solvent, and reacting to obtain polyamic acid solution, (b) coating polyamic acid solution obtained in the step (a) on a silicon plate, heating for removing the solvent, then programmatically heating in a high-temperature oven to complete the imidization process, and obtaining a PI film attached to a silicon plate which is marked as sample A, (c) using chemical vapor deposition to grow graphene on the metal substrate to obtain the first sample, (d) spin-coating polymethyl methacrylate on front side of first sample, heating and solidifying to obtain second sample, (e) placing the back of second sample into plasma bombarding device, vacuumizing and bombarding the plasma to obtain third sample after bombardment, (f) adding third sample facing upwards into etching solution, etching the metal substrate and cleaning with sample A to obtain the fourth sample, and (g) removing polymethyl methacrylate in fourth sample to obtain the fifth sample, blowing dry with nitrogen, coating the polyamic acid solution obtained in the step (a) on graphene surface of fifth sample, completely performing imidization with heating method in the step (b) to obtain a three-layer PI-graphene-PI composite film.