Hydrogen gas barrier property of polyelectrolyte/GO layer-by-layer films

Different types of ultrathin multilayer composite membranes adsorbed on polyethylene terephthalate (PET) substrates are fabricated by the layer-by-layer (LBL) self-assembly technique. The hydrogen gas barrier performances of these membranes are measured using a pressure permeation instrument. Polyethylenimines/graphene oxide (PEI/GO) are chosen as the optimal system; the multilayer film reduces the hydrogen transmission rate of the uncoated PET film from 1357 to 24 cm³/(m² 24 h 0.1 MPa). The membrane assembly process for the PEI/GO system is analyzed with UV-Visible spectroscopy, and the flat morphology of the ultrathin film is observed by scanning electron and atomic force microscopies. Moreover, in order to fully characterize the PEI/GO multilayer film system, we investigate the effects of multiple variables on the hydrogen resistance performance. These include the molecular weight of PEI, concentrations of PEI and GO, number of bilayers, soaking time, and drying methods. The film thickness is found to increase linearly during the LBL assembly process.