Dispersible edge functionalised graphene platelets
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Solution Overview
Problem
Current methods for producing graphene at industrial scales face challenges in achieving high dispersibility and stability in solvents, leading to agglomeration and limited concentrations, which hinders its use in composite materials and applications requiring homogeneous distribution.
Innovation Solution
The development of edge-functionalised graphene platelets with partial functionalisation of edges and surfaces, allowing for stable dispersions up to 700 mg/mL in water and improved electrical conductivity, achieved through a method involving suspension in organic nitrile and ester solvents with ruthenium tetroxide oxidation and subsequent washing and drying processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If liquid-phase exfoliation is used to produce graphene, then large quantities can be produced, but large amounts of solvents are required and dispersibility is poor
Solution Approach 1:
The patent applies local quality by functionalizing only the edge regions of graphene platelets rather than the entire surface. This selective edge functionalization introduces hydrophilic groups (carboxyl, hydroxyl, carbonyl) at the edges while preserving the hydrophobic basal planes, enabling controlled water interaction that improves dispersibility without requiring excessive solvent
Solution Approach 2:
The patent changes the chemical parameters of graphene by introducing oxygen-containing functional groups at the edges through controlled oxidation. This chemical modification alters the surface energy and wettability of edge regions, transforming graphene from hydrophobic to amphiphilic, which significantly improves dispersibility in water and reduces solvent requirements
2Quantity of substance
If graphene is dispersed in water at higher concentrations, then storage and composite fabrication are improved, but graphene agglomerates and restacks
Solution Approach 1:
By functionalizing only the edge regions rather than the entire surface, the patent creates amphiphilic graphene platelets with hydrophilic edges and hydrophobic bases. This local differentiation enables high-concentration dispersions to remain stable, as the hydrophilic edges provide steric and electrostatic stabilization while the hydrophobic bases maintain stacking tendency only when needed for composite formation
Solution Approach 2:
The edge functional groups act as intermediaries that mediate the interaction between hydrophobic graphene basal planes and water. These functional groups at the edges provide hydrophilic anchoring points that prevent complete restacking while allowing controlled aggregation for composite fabrication, enabling stable high-concentration dispersions
3Quantity of substance
If edge functionalization is applied to improve dispersibility, then dispersity increases, but electrical conductivity may be reduced
Solution Approach 1:
The patent applies local quality by restricting functionalization to edge regions only, preserving the electronic structure and high electrical conductivity of the basal planes. The functional groups at edges provide dispersibility while the extended conjugated systems in the basal planes maintain electron transport pathways, achieving both dispersibility and conductivity
Solution Approach 2:
The patent uses partial functionalization (only at edges) rather than complete surface functionalization. This partial action is sufficient to provide the necessary dispersibility while minimizing disruption to the overall electronic structure and conductivity of the graphene platelets
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The edge-functionalised graphene platelets provide enhanced dispersibility and conductivity, enabling stable suspensions for extended periods and facilitating the fabrication of composite materials and electrodes with improved properties.
Implementation Method 1
reacting the solution containing suspended graphite or graphene with an oxidant (such as ruthenium tetroxide) to at least partially functionalise edge regions of the graphite or graphene
Implementation Method 2
graphite is exfoliated into graphene in a liquid media, often by use of an ultrasonication. As the layers of graphene are held together by weak van der Waals forces, ultrasonic waves are able to break apart layers of graphene
Implementation Method 3
As the layers of graphene are held together by weak van der Waals forces, ultrasonic waves are able to break apart layers of graphene
Implementation Method 4
This can further be improved by altering the composition of the liquid media to include solvents or stabilizers to decrease the potential energy barrier between the sheets
Data Source
AI summary
The present disclosure provides a dispersible graphene platelet and a method of making same. The structure of the graphene platelet 10 comprises a base layer 1 of graphene on which at least one discontinuous layer 2, 3, 4 of graphene is stacked, with each layer of graphene above the base layer having a smaller surface area than the layer it is stacked upon. The edges of the base layer and the discontinuous layers stacked upon it are all at least partially functionalised 5, providing a structure with graphene-like properties owing to the base layer and relatively high dispersibility owing to the increased amount of functionalised groups on each platelet. The platelets may be used for a number of applications, for example in the production of electrodes or composite materials.