Impermeable gas barrier coating by facilitated diffusion of ethylenediamine through graphene oxide liquid crystals

A highly impermeable gas barrier coating is developed by intercalating ethylenediamine (EDA) into the nanochannels of graphene oxide (GO). The diffusion of EDA is facilitated in aqueous GO liquid crystal (LC) scaffolds, and the intercalation can be achieved spontaneously in a few seconds. The intercalated EDA not only crosslinks GO but also induces chemical reduction of GO to RGO, making the RGO/EDA coating stable in water. Remarkably, the RGO/EDA coating exhibits extremely low gas permeability ranging from 0.006 to 0.02 barrer for He, H2, N2, and CO2, similar to that of a neat GO film and exceeding the barrier performance of conventional polymers or their composite materials with graphene or nanoclay. The excellent barrier properties can be attributed to the high tortuosity caused by the well-aligned structure of high-aspect-ratio graphene sheets. In addition, the viscoelastic rheological properties of the GOLC could be beneficial for coating RGO/EDA on various substrates with different geometries where gas barrier properties are needed.