Miniemulsion polymerization of styrene using carboxylated graphene quantum dots as surfactant

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

Miniemulsion polymerization using carboxylated graphene quantum dots as surfactants: Effects of monomer and initiator type

Graphene quantum dots (GQDs) are building blocks of emerging interest for fabrication of polymeric nanocomposite materials with a range of potential applications. In the present work, we have conducted a detailed investigation into the use of carboxylated GQDs as surfactants in aqueous miniemulsion polymerization. The cGQDs were prepared by carbonization of dextrose according to a bottom-up hydrothermal approach. It is demonstrated that cGQDs can satisfactorily stabilize miniemulsions of a variety of vinyl monomers including styrene, acrylates and methacrylates. The nature of the initiation system plays a pivotal role in regards to monomer conversion-the water soluble initiator 2,2'-azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride (VA-044) resulted in substantially higher conversions than the oil soluble initiator azobisisobutyronitrile (AIBN). The present results illustrate that these cGQDs have the ability to function as surfactants in miniemulsion polymerization for various vinyl monomer types, which has implications for hybrid nanocomposite nanoparticles and materials synthesis

Ambient-temperature waterborne polymer/rGO nanocomposite films: effect of rGO distribution on electrical conductivity

Copyright © 2019 American Chemical Society. Electrically conductive polymer/rGO (reduced graphene oxide) films based on styrene and n-butyl acrylate are prepared by a variety of aqueous latex based routes involving ambient temperature film formation. Techniques based on miniemulsion polymerization using GO as surfactant and "physical mixing" approaches (i.e., mixing an aqueous polymer latex with an aqueous GO dispersion) are employed, followed by heat treatment of the films to convert GO to rGO. The distribution of GO sheets and the electrical conductivity depend strongly on the preparation method, with electrical conductivities in the range 9 × 10-4 to 3.4 × 102 S/m. Higher electrical conductivities are obtained using physical mixing compared to miniemulsion polymerization, which is attributed to the former providing a higher level of self-alignment of rGO into larger linear domains. The present results illustrate how the distribution of GO sheets within these hybrid materials can to some extent be controlled by judicious choice of preparation method, thereby providing an attractive means of nanoengineering for specific potential applications