title: Surface engineering of graphene quantum dots and their applications as efficient surfactants.
abstract: The surface properties of graphene quantum dots (GQDs) control their dispersion and location within the matrices of organic molecules and polymers, thereby determining various properties of the hybrid materials. Herein, we developed a facile, one-step method for achieving systematic control of the surface properties of highly fluorescent GQDs. The surfaces of the as-synthesized hydrophilic GQDs were modified precisely depending on the number of grafted hydrophobic hexylamine. The geometry of the modified GQDs was envisioned by conducting simulations using density functional theory. In stark contrast to the pristine GQDs, the surface-modified GQDs can effectively stabilize oil-in-water Pickering emulsions and submicron-sized colloidal particles in mini-emulsion polymerization. These versatile GQD surfactants were also employed in liquid-solid systems; we demonstrated their use for tailoring the dispersion of graphite in methanol. Finally, the particles produced by the GQD surfactants were fluorescent due to luminescence of the GQDs, which offers great potential for various applications, including fluorescent sensors and imaging.
authors.affiliation: Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Korea.
authors.forename: Han-Hee
authors.initials: HH
authors.lastname: Cho
authors.affiliation: Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Korea.
authors.forename: Hyunseung
authors.initials: H
authors.lastname: Yang
authors.affiliation: Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Korea.
authors.forename: Dong Jin
authors.initials: DJ
authors.lastname: Kang
authors.affiliation: Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Korea.
authors.forename: Bumjoon J
authors.initials: BJ
authors.lastname: Kim
mesh_terms: D000588:Amines / Q000737:chemistry; D003102:Colloids / Q000737:chemistry; D004655:Emulsions / Q000737:chemistry; D006108:Graphite / Q000737:chemistry*; D018625:Microscopy, Atomic Force; D008855:Microscopy, Electron, Scanning; D058105:Polymerization; D011137:Polystyrenes / Q000737:chemistry; D045663:Quantum Dots / Q000737:chemistry*; D013055:Spectrophotometry, Infrared; D013499:Surface Properties; D013501:Surface-Active Agents / Q000737:chemistry*
chemical_list: D000588:Amines; D003102:Colloids; D004655:Emulsions; D011137:Polystyrenes; D013501:Surface-Active Agents; D006108:Graphite; C007940:hexylamine
keywords: Pickering emulsion; amphiphilicity; graphene quantum dots; surface modification; surfactants