Parametric studies of formation and morphology of sub-micron sized GO stabilized PS/GO containers encapsulating 8-HQ

Abstract

The work identifies parameters and proposes mechanisms that are crucial in making smart containers with encapsulating agents by Pickering emulsion route for anti-corrosion coating and advanced materials applications. We demonstrate the unmodified graphene oxide (GO) particles as potential stabilizers for oil-in-water emulsions not requiring any modification to the properties of the emulsion phases. The model system, GO stabilized styrene in water, was used to explore the mechanistic details of the stable emulsion formation and subsequent formation of polystyrene/graphene oxide (PS/GO) containers after emulsion polymerization. The results indicate a clear size effect during packing of GO at oil-water interface and smaller GO sheets produced homogenous emulsion without any residual water volume. The emulsion droplet size distribution changes from bimodal to monomodal with the increase in GO concentration and it reverses with oil–water phase ratio. For the first time, a correlation was developed between these variables and the size, polydispersity index (PDI), morphology, conversion, and yield of the containers produced by emulsion polymerization. The parametric controls required for preparing PS/GO containers with narrow size distribution (PDI = 0.23), smaller size and various morphologies are discussed, with a probable mechanism. All these studies were carried out in presence of a corrosion inhibitor, 8-Hydroxyquinoline (8-HQ), to be encapsulated in the container. The containers were produced with 75% encapsulation efficiency.