Preparation of modified graphene oxide/polyethyleneimine film with enhanced hydrogen barrier properties by reactive layer-by-layer self-assembly

Hydrogen barrier properties are characteristic of polymeric materials prepared with graphene; thus, they can be considered as a good substitute for the metal body of the traditional hydrogen storage tank. Graphene oxide/polymer layer-by-layer self-assembling film based on noncovalent force shows good hydrogen gas barrier properties. However, the dense film structure can be broken when the film is placed in water environment, especially acidic or alkaline environment, which induces to the leak of the hydrogen gas. Herein, a modified graphene oxide/polyethyleneimine reactive layer-by-layer self-assembled film for the hydrogen barrier was fabricated by the covalent bond self-assembled technology. Graphene oxide was modified with ethylene glycol diglycidyl ether to introduce epoxy groups that can react with polyethyleneimine to form covalent bonds. The modification time, modification pH value, and the feed ratio of graphene oxide/ethylene glycol diglycidyl ether were investigated in detail. Results indicate that the self-assembled films were prepared by covalent bonds between polyethyleneimine and modified graphene oxide. When the modification time was 6 h, pH value was 2, and the feed ratio of graphene oxide/ethylene glycol diglycidyl ether was 0.05/0.23, the hydrogen transmission rate of 10-bilayer modified graphene oxide/polyethyleneimine self-assembled films was 289 cm ³ /m ² ·24 h·0.1 MPa, which was decreased by 78.8% compared to that of the polyethylene terephthalate substrate films (1365 cm ³ /m ² ·24 h·0.1 MPa). Furthermore, the modified graphene oxide/polyethyleneimine reactive layer-by-layer self-assembled films exhibit acid-resistance, alkali-resistance, salt-resistance and thermal-resistance properties.