Pickering miniemulsion polymerization using graphene oxide: effect of addition of a conventional surfactant†
Polystyrene/graphene oxide (PSt/GO) nanocomposite latexes have been prepared by Pickering miniemulsion polymerization in the presence of the conventional surfactant sodium dodecyl sulfate (SDS) in order to investigate its influence on the polymerization mechanism. Miniemulsion polymerization of styrene can be conducted successfully using GO as the sole surfactant, but the polymerization rate is very low. In the presence of SDS, a significant rate enhancement is observed. It has been clarified that the presence of SDS leads to additional nucleation pathways besides monomer droplet nucleation, namely nucleation involving free GO sheets in the aqueous phase as well as homogeneous nucleation. These mechanistic pathways are consistent with the rate enhancement and the increase in molecular weight as well as experimentally observed particle distributions in the presence of SDS. The present results represent a significant step forward in terms of our understanding of the fundamental polymerization mechanism of this Pickering miniemulsion system, which will aid in the preparation of advanced nanocomposite materials based on polymers and graphene (oxide).