The True Amphipathic Nature of Graphene Flakes: A Versatile 2D Stabilizer

Abstract

The fundamental colloidal properties of pristine graphene flakes remain incompletely understood, with conflicting reports about their chemical character, hindering potential applications that could exploit the extraordinary electronic, thermal, and mechanical properties of graphene. Here, the true amphipathic nature of pristine graphene flakes is demonstrated through wet‐chemistry testing, optical microscopy, electron microscopy, and density functional theory, molecular dynamics, and Monte Carlo calculations, and it is shown how this fact paves the way for the formation of ultrastable water/oil emulsions. In contrast to commonly used graphene oxide flakes, pristine graphene flakes possess well‐defined hydrophobic and hydrophilic regions: the basal plane and edges, respectively, the interplay of which allows small flakes to be utilized as stabilizers with an amphipathic strength that depends on the edge‐to‐surface ratio. The interactions between flakes can be also controlled by varying the oil‐to‐water ratio. In addition, it is predicted that graphene flakes can be efficiently used as a new‐generation stabilizer that is active under high pressure, high temperature, and in saline solutions, greatly enhancing the efficiency and functionality of applications based on this material.

Graphene Enhances Actin Filament Assembly Kinetics and Modulates NIH-3T3 Fibroblast Cell Spreading

“…We first evaluated the effects of graphene flakes on steady-state actin polymerization using TIRF microscopy imaging. We chose pristine graphene flakes rather than graphene oxide flakes or its derivatives since pure graphene flakes have well-defined hydrophilic and hydrophobic regions, demonstrated by a recent study [ 35 ]. We polymerized actin filaments (18–20% Alexa-labeled) in the absence (control) or presence of graphene flakes (0.5–20 μg/mL), and then measured the steady-state actin filament lengths in the presence of graphene flakes (0.5–20 μg/mL) ( Figure S1 ).…”

Development of thermo‐regulating fabrics with enhanced heat dissipation via graphene‐modified n‐octadecane microcapsules

“…[65,66] Graphene particles stabilize oil droplets by attracting water at the corners on the other hand repelling the water on the surface. [66] When microcapsules were coated on PET fabrics, it was observed that the microcapsules remained between warp and weft threads. However, a coating was obtained in which the microcapsules were homogeneously distributed over the fabric surface.…”

“…The graphene particles in the emulsion act as a surfactant, causing the PCM droplets to decrease in diameter. [65,66] Graphene particles stabilize oil droplets by attracting water at the corners on the other hand repelling the water on the surface. [66] When microcapsules were coated on PET fabrics, it was observed that the microcapsules remained between warp and weft threads.…”

Conductive Nanofilms with Oppositely Charged Reduced Graphene Oxides as a Base for Electroactive Coatings and Sensors

“…The electrical conductivity of the graphene structure is partly regained, and rGO can be dispersed in various solvents [15], including water, forming stable suspensions that can be used for deposition on various surfaces. Additionally, due to the presence of hydrophobic (basal planes) and hydrophilic domains, rGO is amphiphilic and can be used for foam or Pickering emulsions stabilization [16,17]. Furthermore, the functional groups remaining after the reduction process facilitate covalent modification by attachment of various functional groups, ligands, etc.…”