Miniemulsion polymerization of styrene using carboxylated graphene quantum dots as surfactant

The utilization of functionalized graphene quantum dots to create various types of Pickering emulsions is of great interest for fabrication of fluorescent/photoluminescent nanocomposite materials. In the present work, aqueous miniemulsion polymerization of styrene has been conducted using carboxylated graphene quantum dots (cGQDs) as the sole surfactant. The cGQDs, having average lateral dimensions of 2.6 nm, were synthesized by carbonization of dextrose according to a bottom-up hydrothermal approach. It is demonstrated that styrene-water miniemulsions obtained via ultrasonication can be stabilized using these cGQDs. Miniemulsion polymerizations of styrene using a wide range of cGQD concentration were performed to fabricate nanocomposite latexes. The obtained hybrid polymer nanoparticles had an average diameter of approximately 200 nm with zeta potentials in the range from −23.1 to −44.7 mV, with the absolute zeta potential increasing with increasing cGQD loading. Negative zeta potential values originate from dissociated carboxyl groups of the cGQDs. The present work demonstrates that these cGQDs can be used as effective surfactants in miniemulsion polymerization, which is of interest in regards to synthesis of novel types of hybrid nanocomposite nanoparticles and materials. Carboxylated graphene quantum dots (cGQDs) were synthesized from dextrose and sulfuric acid via a hydrothermal process, and subsequently used as sole surfactant in miniemulsion polymerization of styrene.