title: Nanoscale insight into the exfoliation mechanism of graphene with organic dyes: effect of charge, dipole and molecular structure.
abstract: We study the mechanism of surface adsorption of organic dyes on graphene, and successive exfoliation in water of these dye-functionalized graphene sheets. A systematic, comparative study is performed on pyrenes functionalized with an increasing number of sulfonic groups. By combining experimental and modeling investigations, we find an unambiguous correlation between the graphene-dye interaction energy, the molecular structure and the amount of graphene flakes solubilized. The results obtained indicate that the molecular dipole is not important per se, but because it facilitates adsorption on graphene by a "sliding" mechanism of the molecule into the solvent layer, facilitating the lateral displacement of the water molecules collocated between the aromatic cores of the dye and graphene. While a large dipole and molecular asymmetry promote the adsorption of the molecule on graphene, the stability and pH response of the suspensions obtained depend on colloidal stabilization, with no significant influence of molecular charging and dipole.
authors: ISOF-National Research Council, Bologna, Italy.
authors: Andrea
authors: A
authors: Schlierf
authors: Huafeng
authors: H
authors: Yang
authors: Elias
authors: E
authors: Gebremedhn
authors: Emanuele
authors: E
authors: Treossi
authors: Luca
authors: L
authors: Ortolani
authors: Liping
authors: L
authors: Chen
authors: Andrea
authors: A
authors: Minoia
authors: Vittorio
authors: V
authors: Morandi
authors: Paolo
authors: P
authors: Samorì
authors: Cinzia
authors: C
authors: Casiraghi
authors: David
authors: D
authors: Beljonne
authors: Vincenzo
authors: V
authors: Palermo