Super gas barrier and selectivity of graphene oxide-polymer multilayer thin fims

Thin films made by branched polyethylenimine (PEI) and graphene oxide (GO) using Layer-by-layer (LbL) deposition in aqueous suspensions are studied on the focus of oxygen barrier. Linear thickness and mass growth were observed with 4.3 ~ 5.0 nm per bilayer. AFM and TEM images showed the discrete nanobrick wall structure and polydispersed graphene sheets. A 30 bilayer PEI/GO film, with a 149 nm thickness, decrease the oxygen transmission rate by a factor of 45 and obtained an oxygen permeability within the same order of magnitude as a SiO_x coating (6.6 × 10^-20 cm³ (STP) · cm/cm² · s · Pa). This impressive gas barrier makes it a promising alternative to currently used materials for flexible electronics and food packaging.