Graphene Exfoliation via Shear Force and Silica Stabilization
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Solution Overview
Problem
Existing graphene products are not stable due to the presence of thick layers, which leads to precipitation and limited usability in liquid systems, and 'top-down' methods yield low quantities of mono-layer graphene.
Innovation Solution
A method involving a liquid precursor of graphene and silica in an organic solvent, subjected to high pressure sheer force through a metal cylinder and flat plate, breaking down thick graphene layers into stable, thin layers dispersed in a silica gel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If top-down liquid-phase exfoliation is used to produce graphene, then high concentration of suspended flakes is achieved, but the yield of mono-layer graphene is low and thick layers precipitate
Solution Approach 1:
The patent applies segmentation by introducing silica particles that act as spacers to divide and separate graphene layers during exfoliation. The silica particles prevent graphene sheets from restacking, thereby segmenting the thick aggregated layers into thinner, more uniform dispersed layers, improving layer thickness control while maintaining high suspension concentration
Solution Approach 2:
The patent uses silica particles as an intermediary substance between graphene sheets. These silica particles mediate the interaction between graphene layers by physically separating them and providing steric stabilization, preventing direct contact and aggregation of thick graphene layers, thus improving both concentration and layer uniformity
2Quantity of substance
If commercially available graphene products are used, then high concentration is achieved, but stability is poor due to precipitation of thick layers
Solution Approach 1:
The patent introduces silica particles as intermediary stabilizers that prevent direct aggregation of graphene sheets. These silica particles act as physical barriers and provide steric stabilization, maintaining dispersion stability at high concentrations by preventing the precipitation of thick graphene layers
Solution Approach 2:
The patent creates a composite dispersion system combining graphene, silica particles, and organic solvent. This composite structure leverages the stabilizing properties of silica to maintain high concentrations of graphene without precipitation, achieving both high quantity and improved stability through material composition
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 process stabilizes graphene platelets in a fluid dispersion, maintaining their two-dimensional configuration and preventing aggregation, enabling their use in various applications such as coatings and car care products with enhanced properties.
Implementation Method 1
directing the liquid precursor through an orifice comprising a metal cylinder and a flat metal plate. The metal cylinder may be pressed against the flat metal plate, and the liquid precursor may be forced through an opening on the flat metal plate
Implementation Method 2
the silica may form a gel comprising a three-dimensional structure
Implementation Method 3
the graphene is dispersed in the gel formed by the silica
Implementation Method 4
providing a liquid precursor comprising graphene and silica in an organic solvent
Data Source
AI summary
The present disclosure provides a method of graphene exfoliation and/or stabilization. Both graphene and silica are mixed in an organic solvent to form a liquid precursor, which is then directed through an orifice formed by a metal cylinder and a flat metal plate. The metal cylinder is pressed against the flat metal plate by a high pressure. The high shear between the metal cylinder and the flat metal plate breaks down the thick layers of graphene to thin layers, which are stably dispersed in the gel formed by the silica.