Polymer/graphite nanocomposites: Effect of reducing the functional groups of graphite oxide on water barrier properties

• The barrier properties of polymer/graphene nanocomposites were studied.
• Nanocomposites made with reduced graphene oxide showed improved barrier properties.
• This was due to the hydrophobic nature of reduced graphene oxide nanosheets.
• This resulted in better barrier properties compared to as-prepared graphite oxide.

Water barrier properties (i.e., water resistance) of poly(styrene-co-butyl acrylate)/graphite oxide (poly(St-co-BA)/GO) nanocomposites were studied using hydrophobicity and permeability analysis. Poly(St-co-BA)/GO nanocomposite latices were obtained using the miniemulsion polymerization technique. The hydrophobicity of the synthesized nanocomposites was studied using contact angle measurements, while water permeability was obtained by measuring the moisture vapor transmission rate (MVTR). The nanocomposites were treated with hydrazine hydrate in order to reduce the functional groups on graphite oxide (GO). The focus was on determining the effect of reducing the functional groups of GO on the water barrier properties of its polymer nanocomposites. In general, the nanolayered graphene platelets in GO and RGO resulted in lower water permeation in the final films compared to pure polymer. However, results showed that nanocomposites containing the reduced-GO (RGO) had better water resistance and barrier properties compared to those made with unreduced GO (i.e., as-prepared GO). The nanocomposites containing RGO had higher hydrophobicity and lower water uptake and MVTR compared to those made with as-prepared GO, resulting in better barrier performance. This was attributed to the high hydrophobic nature of the RGO, which exhibited lower water solubility that resulted in films with lower MVTR values compared to those made with as-prepared GO.

Polymer/graphite nanocomposites (PGNs) were synthesized using graphite oxide (GO) by miniemulsion polymerization. GO was prepared by the oxidation process of natural graphite using potassium permanganate in the presence of concentrated sulfuric acid. The resultant functionalized graphite (GO) was used to prepare poly(styrene-co-butyl acrylate) (poly(St-co-BA)) nanocomposites latices in miniemulsions. The functional groups of GO were then reduced by treating the nanocomposite latices using a strong reducing agent, hydrazine hydrate. The water barrier properties (hydrophobicity, water uptake and moisture vapor transmission rate) of the resultant films produced from the obtained nanocomposite latices containing the reduced GO (RGO) were studied. Results showed that the nanocomposite films containing the RGO had less affinity to water and better water barrier properties compared to those of the same nanocomposites, which contain unmodified (i.e., as-prepared) GO.Figure optionsDownload as PowerPoint slide