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Updated: Mar 21, 2026
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Synthesis of Graphene Nanofluids with Controllable Flake Size Distributions
Published on: July 17, 2019
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Colloidal Stability of Graphene Oxide: Aggregation in Two Dimensions
1Department of Polymer Engineering and Colour Technology, Amirkabir University of Technology , Tehran 15875-4413, Iran.
Summary
Graphene oxide (GO) colloidal stability is explained by an improved DLVO model, showing 2D effects on forces and pH insensitivity. Reduced GO (rGO) is less stable due to increased van der Waals forces and surface changes.
Area of Science:
- Materials Science
- Colloid and Surface Chemistry
Background:
- Colloidal stability is crucial for nanomaterial applications.
- Graphene oxide (GO) presents unique challenges due to its 2D nature.
- Existing models may not fully capture GO's behavior.
Purpose of the Study:
- To investigate the colloidal stability of graphene oxide (GO) and reduced graphene oxide (rGO) in various media.
- To develop and validate an improved aggregation model based on DLVO theory for 2D materials.
- To understand the influence of solvent properties and pH on GO dispersion.
Main Methods:
- Application of Derjaguin-Landau-Verwey-Overbeek (DLVO) theory to ultrathin colloidal flakes.
- Experimental determination of critical coagulation concentrations (CCC) in monovalent salt solutions.
- Analysis of GO aggregation in aqueous, organic, and mixed solvent systems.
Main Results:
- The 2D nature of GO significantly impacts van der Waals forces and scaling laws.
- Experimental CCC values for GO align with DLVO predictions.
- GO colloidal stability is less sensitive to pH changes than traditional 3D colloids.
- Reduced GO (rGO) exhibits lower stability due to increased van der Waals forces and surface chemistry modifications.
- Stable GO dispersions are achieved in polar organic solvents, with stability influenced by solvent dielectric constant and molecular size.
- Unexpected stability in polar solvents at high salt/acid concentrations is attributed to solvation forces.
Conclusions:
- The improved DLVO model accurately predicts GO and rGO colloidal stability.
- Solvation forces play a key role in stabilizing GO in polar organic solvents.
- Understanding these factors is essential for controlling GO dispersion and applications.
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