Tuning nanostructure of graphene oxide/polyelectrolyte LbL assemblies by controlling pH of GO suspension to fabricate transparent and super gas barrier films

Abstract

A technique of layer-by-layer (LbL) self-assembly was used to prepare transparent multilayered gas barrier films consisting of graphene oxide (GO)/branched poly(ethylenimine) (BPEI) on a poly(ethylene terephthalate) substrate. The effect of the GO suspension pH on the nanostructure and oxygen barrier properties of the GO/BPEI film was investigated. The oxygen barrier properties of the assemblies were shown to be highly dependent on the pH. It was demonstrated that the film assemblies prepared using a GO suspension with a pH of 3.5 exhibited very dense and ordered structures and delivered very low oxygen transmission rates (the lowest was <0.05 cm(3) m(-2) day(-1)). The assemblies were characterized with ultraviolet-visible spectroscopy and ellipsometry to identify the film growth mechanism, and the result indicated a linear growth behavior. To analyze the nanostructure of the films, atomic force microscopy, transmission electronic microscopy, and grazing incidence wide-angle X-ray diffraction were used.

Fabrication of ultrahigh hydrogen barrier polyethyleneimine/graphene oxide films by LBL assembly fine-tuned with electric field application

“…The absorbance values of the self-assembled films prepared at three different voltages all showed a linear increase with the number of bilayers. This trend is consistent with that reported in previous studies [36] . Our results indicated that LBL self-assembly is a stacking-growth process at a constant rate under an applied electric field.…”

Fabricating graphene oxide-based ultrathin hybrid membrane for pervaporation dehydration via layer-by-layer self-assembly driven by multiple interactions

“…As shown in Fig. 3d, no nanopores exist on (GE/GO) 1 /H-PAN membrane surface, due to the micrometer-scale size of GO along horizontal direction, as well as the even spreading and packing of GO on membrane surface resulting from the appropriate pH condition [22]. As a result, the required deposition cycle number for fabricating defect-free layer is reduced, thus greatly simplifying the membrane fabrication procedure.…”

“…The combination of above factors leads to The effect of pH value during self-assembly process on membrane separation performance was investigated as listed in Table 1. When the pH value of GE solution and GO dispersion is 2.0, the lower charge density on GO leads to aggregation [22], which results in the uneven spreading and packing of GO and decreases the interaction sites between GE and GO. Furthermore, the subsequent deposition of GE is also influenced with uneven deposition and decreased deposition amount.…”

“…Afterwards, the zeta potential exhibits a growing tendency with pH value, resulting from the compression of double electric layer outside GO at higher ionic concentration [22]. To achieve a self-assembly process with high interlayer cross-linking density, both GE and GO need to be adsorbed in a highly charged state [26].…”

Self‐Assembled Graphene‐Based Architectures and Their Applications

“…It was noticed that a graphene/polymer assembly could provide a tightly packed architecture with insufficient gas diffusion channels 80. Chen et al employed similar methods to construct gas barrier films using GO/PEI multilayered structures and demonstrated that both the pH for the GO suspension and the GO/PEI bilayer number had great influence on the oxygen barrier performance for the multilayered film,81 implying the intercalated structures of tightly oriented and stacked GO/PEI system. Enhanced mechanical properties were also reported by Grunlan and co‐workers for a PAA/PVP‐G system.…”