Graphene and graphene oxide and their uses in barrier polymers

Abstract

Currently, there is great interest in graphene-based devices and applications because graphene has unique electronic and material properties, which can lead to enhanced material performance. Graphene may be used in a wide variety of potential applications from next-generation transistors to lightweight and high-strength polymeric composite materials. Graphene, which has atomic thickness and two-dimensional sizes in the tens of micrometer range or larger, has also been considered a promising nanomaterial in gas-or liquid-barrier applications because perfect graphene sheets do not allow diffusion of small gases or liquids through its plane. Recent molecular simulations and experiments have demonstrated that graphene and its derivatives can be used for barrier applications. In general, graphene and its derivatives can be applied via two major routes for barrier polymer applications. One is the transfer or coating of few-layered, ultrathin graphene and its derivatives, such as graphene oxide (GO) and reduced graphene oxide (rGO), on polymeric substrates. The other is the incorporation of fully exfoliated GO or rGO nanosheets into the polymeric matrix. In this article, we review the state-of-the-art research on the use of graphene, GO, and rGO for barrier applications, including few-layered graphene or its derivatives in coated polymeric films and polymer nanocomposites consisting of chemically exfoliated GO and rGO nanosheets, and their gas-barrier properties. As compared to other nanomaterials being used for barrier applications, the advantages and current limitations are discussed to highlight challenging issues for future research and the potential applications of graphene/ polymer, GO/polymer, and rGO/polymer composites.

Impermeable barrier films and protective coatings based on reduced graphene oxide

“…Although such unique and contrasting properties may be useful for certain applications, many others need flexible barrier films with little oxygen and moisture permeation. The required rates are typically o0.1 g of water per m 2 per day and down to 10 À 6 g m À 2 per day in the case of flexible organic electronics 9,14 . Achieving these ultra-low rates for the case of flexible coatings is extremely challenging 14 .…”

“…However, T-RGO membranes are extremely fragile and contain many structural defects, which results in notable water permeation 5,9 . A high density of defects in CVD graphene also limits its possible uses 9,10 . Similarly, GO-polymer composites have so far exhibited gas permeability too high to consider them for realistic applications 9 .…”

“…A high density of defects in CVD graphene also limits its possible uses 9,10 . Similarly, GO-polymer composites have so far exhibited gas permeability too high to consider them for realistic applications 9 . To increase the quality of GO-based coatings, it is essential to decrease the number of defects formed during the reduction process [23][24][25][26][27][28] (see Supplementary Fig.…”

Evaluation of Aging Resistance of Graphene Oxide Modified Asphalt

“…The SEM pictures were taken on the microscope at the voltage of 5 KV where the magnification of the pictures could be obtained from 18-300,000 times. The GO, in general, would be affected by thermal shock for its structural metastability [21], so the GO samples were dried at 50 • C.…”

“…Most researchers believe that epoxy and hydroxyl groups are on the basal plane, whereas carbonyl and carboxylic acid groups are at the edges [24][25][26][27]. These oxygen functional groups allow the GO to be easily and evenly dispersed because they decrease the van der Waals forces of the GO molecules [21]. The microstructure of the GO was studied by SEM, Figure 1a,b are SEM images of the GO magnified 500 and 1000 times, respectively.…”