Anion Exchange Membrane In-Situ Quaternarization
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Solution Overview
Problem
Existing methods for quaternarization of anion conducting polymer membranes in roll-to-roll processing are inefficient due to slow diffusion of tertiary amines, requiring batch processing and disrupting continuous operation, and result in suboptimal ion conductivity and mechanical properties.
Innovation Solution
Incorporating a non-cross-linking tertiary amine directly into the prepolymer/solvent mixture during membrane casting, allowing simultaneous quaternarization and cross-linking, which enhances ion conductivity and mechanical stability without the need for post-casting soaking in amine solutions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If batch processing with post-casting soaking in amine solutions is used, then quaternarization can be achieved, but continuous roll-to-roll processing is disrupted and productivity decreases
Solution Approach 1:
The patent applies preliminary action by incorporating the tertiary amine directly into the casting solution before membrane formation. This allows the quaternarization reaction to occur during the casting process itself, rather than requiring a separate post-casting soaking step. The ionic groups are formed in-situ as the membrane is being created, enabling continuous roll-to-roll processing while achieving complete quaternarization.
2Reliability
If slow diffusion of tertiary amines is used in conventional methods, then quaternarization can occur, but processing time increases and continuous operation is interrupted
Solution Approach 1:
By pre-mixing the tertiary amine with the casting solution, the patent eliminates the time-consuming diffusion step required in conventional methods. The amine is already present in the solution during casting, so the reaction occurs immediately as the membrane forms, dramatically reducing processing time and enabling continuous operation.
Solution Approach 2:
The casting solution acts as an intermediary medium that facilitates the quaternarization reaction. By dissolving the tertiary amine in the casting solution, the patent creates a homogeneous mixture where the amine can readily access and react with the polymer chains during membrane formation, avoiding the slow diffusion process through already-formed dense membranes.
3Reliability
If post-casting soaking in amine solutions is performed, then ion conducting groups are formed, but hazardous and expensive tertiary amines are consumed in large quantities
Solution Approach 1:
The patent reduces amine consumption by incorporating the exact stoichiometric amount needed directly into the casting solution. This eliminates the excessive amine consumption associated with post-casting soaking methods, where large volumes of amine solution are required to penetrate and fully quaternize the already-formed membrane. The in-situ formation during casting ensures efficient utilization of the amine.
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
This approach enables the production of anion conducting membranes with superior ionic conductivity and mechanical properties, facilitating continuous roll-to-roll processing and reducing the use of hazardous and expensive tertiary amines.
Implementation Method 1
The polymer is converted into an ion conducting polymer by reacting the pendent alkyl halide with a tertiary amine to form a quaternary ammonium cation with mobile anion
Implementation Method 2
control over excessive water uptake by cross-linking
Data Source
AI summary
In a method of forming an anion conducting polymer membrane, a prepolymer membrane solvent-casting solution is generated. At least one non-cross-linking tertiary amine is added to the prepolymer membrane solvent-casting solution. The membrane is cast from the at least one non-cross-linking tertiary amine and the prepolymer membrane solvent-casting solution after the adding step. In another method of forming an anion conducting polymer membrane, a prepolymer membrane solvent-casting solution is generated. At least one non-cross-linking tertiary amine is added to the prepolymer membrane solvent-casting solution. The membrane is cast from the at least one non-cross-linking tertiary amine and the prepolymer membrane solvent-casting solution after the adding step.