Edge-Grafted Graphene Aqueous Dispersion via Low-Damage Exfoliation
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Solution Overview
Problem
Existing methods for preparing graphene result in structural defects, topological imperfections, and poor electrical and thermal conductivity due to mechanical exfoliation and chemical oxidation, while stable aqueous dispersions of graphene are not efficiently achieved, leading to limited large-scale applications.
Innovation Solution
Edge-grafting-modified graphene is prepared using a milling disc process with a water-soluble polymer, which minimizes structural damage and enables stable aqueous dispersions by grafting the polymer to the graphene edges, enhancing exfoliation efficiency and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If mechanical exfoliation method is used to prepare graphene, then large-scale production is achieved, but structural defects and topological imperfections occur
Solution Approach 1:
The patent uses water-soluble polymers as intermediary substances to facilitate the exfoliation of graphite into graphene. The polymers adsorb onto the graphene surface during mechanical exfoliation, preventing direct contact and damage between graphene sheets, thereby reducing structural defects while enabling large-scale production.
Solution Approach 2:
The patent changes the physical and chemical parameters of the exfoliation process by controlling polymer concentration, pH value, and ionic strength to optimize the balance between production efficiency and graphene quality, minimizing structural defects while maintaining high productivity.
2Ease of manufacture
If redox method is used to prepare graphene, then graphene oxide is obtained through chemical exfoliation, but serious waste liquid pollution is caused
Solution Approach 1:
The patent converts the harmful strong oxidants traditionally used in redox methods into benign water-soluble polymers that serve dual purposes: facilitating exfoliation and acting as stabilizing agents, thereby eliminating waste liquid pollution while maintaining ease of manufacture.
Solution Approach 2:
The patent creates an environmentally friendly reaction environment by replacing hazardous chemical oxidants with inert water-soluble polymers, eliminating the generation of harmful waste liquids while maintaining effective chemical exfoliation capabilities.
3Ease of manufacture
If strong oxidants are used in redox method, then graphene oxide is prepared, but electrical properties are lost
Solution Approach 1:
The patent uses water-soluble polymers as intermediaries that enable exfoliation without the need for strong oxidants, preserving the electrical properties of graphene while still achieving effective preparation of graphene oxide through milder chemical treatment.
Solution Approach 2:
The patent changes the oxidation parameters from strong chemical oxidants to controlled mild oxidation conditions combined with polymer assistance, maintaining the electrical properties of graphene while still achieving effective graphene oxide preparation.
4Stability of the object's composition
If water-soluble polymer is grafted to graphene edges, then stable aqueous dispersion is formed, but grafting process complexity increases
Solution Approach 1:
The patent employs a self-service mechanism where water-soluble polymers automatically adsorb and graft onto graphene edges during the exfoliation process itself, eliminating the need for separate grafting steps and reducing process complexity while achieving stable aqueous dispersion.
Solution Approach 2:
The patent merges the exfoliation process and the grafting process into a single integrated operation, where polymer adsorption and graphene formation occur simultaneously, thereby reducing overall process complexity while maintaining dispersion stability.
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 method produces large, stable graphene flakes with maintained electrical and thermal conductivity, forming aqueous dispersions that remain stable for over a year, suitable for various applications.
Implementation Method 1
edge-grafting-modified graphene, comprising a graphene and a water-soluble polymer grafted on the edge thereof
Implementation Method 2
milling disc process with a water-soluble polymer, which minimizes structural damage and enables stable aqueous dispersions
Implementation Method 3
forming aqueous dispersions that remain stable for over a year
Data Source
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AI summary
The present invention belongs to the technical field of graphene preparation, and relates to an edge-grafting-modified graphene, an aqueous dispersion thereof, and a preparation method therefor. The edge-grafting-modified graphene comprises graphene and a water-soluble high-molecular polymer grafted on the edge of the graphene. On the basis of the total mass of the edge-grafting-modified graphene, the mass content of the water-soluble high-molecular polymer grafted in the edge-grafting-modified graphene is 1-30%. Compared with milling techniques such as ultrasound milling, ball milling and sand milling, milling discs have a weak damage effect on the crystal structure of graphite and therefore can easily prepare large lamellar graphene. Additionally, the water-soluble high-molecular polymer can improve the viscosity of a solution and thus indirectly transfer a shearing force between milling discs to graphite flakes, thereby further lowering the damage to crystal lattices of graphite and improving the exfoliation effect of the graphite flakes. In addition, the water-soluble high-molecular polymer can be grafted to graphene, and has a stabilization effect, thereby forming a stable aqueous dispersion of the edge-grafting-modified graphene.