Synthesis of graphene-based polymeric nanocomposites using emulsion techniques

Graphene features an array of extraordinary mechanical, physical and electrical properties, and it is of great interest to impart such properties to polymeric materials by use of graphene and its derivatives as filler materials. The focus of this comprehensive review is on the preparation of graphene-based polymeric nanocomposite materials by use of synthetic approaches involving aqueous emulsions of polymer (nano)particles. These techniques can be broadly categorized as in situ polymerization (where the monomer(s) is/are polymerized in the presence of the composite phase) and physical mixing, where an aqueous dispersion of polymer particles is prepared separately and subsequently mixed with an aqueous dispersion of graphene-based material. Many of these techniques involve the use of derivatives of graphene such as graphene oxide and “reduced” graphene oxide. The fundamental challenge is that graphene as well as graphene oxide have low compatibility with most synthetic polymers, and it is consequently difficult to prepare homogeneous polymer nanocomposites without aggregation and restacking. One of the important features of graphene oxide is that it can act as a surfactant in oil-water emulsions, which has been exploited extensively for preparation of a range of composite particles/materials. Polymer/graphene nanocomposite synthesis via emulsion-based approaches is an active field of research with plenty of opportunities for significant future advancement with a range of potential applications.