Localized In situ Polymerization on Graphene Surfaces for Stabilized Graphene Dispersions

We demonstrate a novel in situ polymerization technique to develop localized polymer coatings on the surface of dispersed pristine graphene sheets. Graphene sheets show great promise as strong, conductive fillers in polymer nanocomposites; however, difficulties in dispersion quality and interfacial strength between filler and matrix have been a persistent problem for graphene-based nanocomposites, particularly for pristine graphene. With this in mind, a physisorbed polymer layer is used to stabilize graphene sheets in solution. To create this protective layer, we formed an organic microenvironment around dispersed graphene sheets in surfactant solutions, and created a nylon 6, 10 or nylon 6, 6 coating via interfacial polymerization. Technique lies at the intersection of emulsion and admicellar polymerization; a similar technique was originally developed to protect luminescent properties of carbon nanotubes in solution. These coated graphene dispersions are aggregation-resistant and may be reversibly redispersed in water even after freeze-drying. The coated graphene holds promise for a number of applications, including multifunctional graphene-polymer nanocomposites.