High-Aspect-Ratio Sheet Silicate Lamellae Without Shear Exfoliation
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Solution Overview
Problem
Existing methods fail to produce sheet silicate lamellae with extremely high aspect ratios and layer charges above 0.55 p.f.u., which are necessary for enhancing the barrier and flame retardancy properties of composite materials, as they either require external shearing forces that break tactoids or do not achieve delamination in polar solvents.
Innovation Solution
Delaminating a 2:1 sheet silicate with ordered interstratification using a solvent mixture of water and a monoalcohol with an alkylammonium salt to achieve sheet silicate lamellae with an average aspect ratio of at least 10,000 and a Lagaly layer charge of 0.56 to 0.90 p.f.u., without the need for external shearing forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If sheet silicates with high layer charge are introduced into polar solvent to increase aspect ratio, then the barrier properties improve, but the sheet silicates no longer exfoliate due to high layer charge
Solution Approach 1:
The patent uses non-polar solvents (hydrocarbons) as intermediaries to facilitate the exfoliation of high layer charge sheet silicates. These non-polar solvents act as mediators that can penetrate the interlayer spaces of sheet silicates with layer charges exceeding 0.55 p.f.u., enabling delamination without requiring external shearing forces, thereby resolving the contradiction between high aspect ratio and exfoliation capability
Solution Approach 2:
The patent changes the solvent parameter from polar to non-polar to enable exfoliation of high layer charge sheet silicates. By using hydrocarbons with specific chain lengths (C15-C30) as the solvent medium, the patent achieves delamination of sheet silicates that would otherwise remain stacked due to their high layer charge, thus maintaining both high aspect ratio and exfoliation capability
2Reliability
If external shearing forces are applied to achieve exfoliation of sheet silicates, then delamination occurs, but the tactoids break and aspect ratio is reduced
Solution Approach 1:
The patent replaces the mechanical exfoliation method (using external shearing forces) with a chemical solution method. By using non-polar solvents that can penetrate and swell the interlayer spaces of sheet silicates, the patent achieves delamination through chemical interaction rather than mechanical force, thereby preventing tactoid breakage and maintaining high aspect ratios
Solution Approach 2:
The non-polar solvent acts as an intermediary that facilitates delamination without requiring mechanical stress. The solvent molecules insert themselves between the silicate layers, reducing the interlayer bonding forces and enabling spontaneous delamination, thus achieving both reliable delamination and preservation of tactoid integrity
3Reliability
If layer charge is increased to enhance barrier properties, then composite material performance improves, but exfoliation in polar solvent becomes impossible
Solution Approach 1:
The patent changes the solvent polarity parameter to enable processing of high layer charge sheet silicates. By switching from polar to non-polar solvents, the patent makes it possible to exfoliate sheet silicates with layer charges of 0.56-0.90 p.f.u., thereby maintaining both high barrier properties and ease of manufacture through a feasible exfoliation process
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 resulting sheet silicate lamellae significantly improve the barrier and flame retardancy properties of composite materials by achieving high aspect ratios and stable delamination, overcoming the limitations of prior methods.
Implementation Method 1
treating a 2:1 sheet silicate (A) with a solvent mixture of water and a monoalcohol having 1 to 4 carbon atoms that comprises an alkylammonium salt
Implementation Method 2
introducing the 2:1 sheet silicate having an ordered interstratification and separated under (ii) into water to produce an aqueous dispersion comprising sheet silicate lamellae
Data Source
AI summary
The present invention relates to sheet silicate lamellae of a 2:1 sheet silicate with a high aspect ratio, to a method for producing these sheet silicate lamellae and to an aqueous dispersion which comprises the sheet silicate lamellae. The present invention further relates to the use of the sheet silicate lamellae of the invention for producing a composite material, and also to a corresponding composite material comprising or obtainable using the sheet silicate lamellae, more particularly for use as a diffusion barrier or as a flame retardant.