Pristine Graphene Microspheres by the Spreading and Trapping of Graphene at an Interface

Abstract

The interfacial spreading and exfoliation of graphene was used to create low-density, hollow microspheres defined by a thin shell of graphene. The spheres were templated by a thermodynamically driven self-assembly process in which graphite spontaneously exfoliated and spread at the high-energy interfaces of a water-in-oil emulsion. Graphene thus acted as a 2D surfactant to stabilize the dispersed water droplets utilized as polymerization templates. Using a mixture of organic solvent and monomer as the emulsion oil phase, polystyrene-coated hollow graphene microspheres were created. These spheres were characterized by optical and electron microscopy, thermo-gravimetric analysis, nanoindentation, and particle sizing. The mechanism leading to the microsphere surface morphology and shape is discussed, with the oil phase composition shown to play a critical role.

Graphene nanosheet stabilized Pickering emulsion and its polystyrene nanocomposites

“…Further analysis in Figure 2a, the results show that 0.41 wt% PG powders can form fully enclosed emulsion droplets properly without light‐transmitting holes. It is caused by the increase content of PG that results in more PG spontaneous spreading and exfoliates at the oil–water interface to cover the hole 23 . These results provides a reference to balance the size of droplets and the properties of materials.…”

“…It is caused by the increase content of PG that results in more PG spontaneous spreading and exfoliates at the oil-water interface to cover the hole. 23 These results provides a reference to balance the size of droplets and the properties of materials. From the XRD and XPS spectra in Figures S3 and S4, the ratio of carbon to oxygen in the natural PG powders is 96.46/3.54.…”

“…Some researchers had found that there is a thin water layer on the surface of the hydrophilic flask wall, when the water layer is in contact with heptane vapor, leading to a high‐energy interface 21 . When the PG particles are located at this interface, a few PG could “climb” the surface to minimize the interfacial energy, thus exfoliating out the thin layer of GNs 22–24 . The PG particles cannot continue to exfoliate once the oil–water interface is covered by GNs 25 .…”

“…21 When the PG particles are located at this interface, a few PG could "climb" the surface to minimize the interfacial energy, thus exfoliating out the thin layer of GNs. [22][23][24] The PG particles cannot continue to exfoliate once the oil-water interface is covered by GNs. 25 Therefore, it leads to a low content of GNs.…”

Study on the relationship between the tribological properties and oxidation degree of graphene derivatives in O/W emulsion

“…It has excellent mechanical and thermal properties as well as good physical and chemical stability. Graphene derivatives have also attracted considerable attention in the field of emulsion technology [13,14] and tribology [15]. For the application in emulsions, the graphene derivative can be used as an emulsifier to prepare a Pickering emulsion.…”