Crosslinked Anion Exchange Membranes for Conductivity and Stability
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Solution Overview
Problem
Current composite anion exchange membranes (AEMs) suffer from poor chemical stability and high water absorption at elevated temperatures, leading to anionic ionomer washout and low conductivity, which are interlinked issues affecting their utility.
Innovation Solution
The crosslinking of ionomers within a composite matrix using heat, UV, IR post-treatment, or chemical agents, such as polyisocyanates and polyamines, to create ionic crosslinks, improve mechanical and thermal stability, and reduce water swelling, while maintaining conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If anion exchange membranes are used to achieve excellent proton conductivities, then conductivity is improved, but water absorption increases excessively at elevated temperatures
Solution Approach 1:
The patent employs composite anion exchange membranes combining poly(ether sulfone) backbone with grafted quaternary ammonium groups and hydrophobic side chains. This composite structure achieves excellent anionic conductivity while limiting excessive water absorption through the balanced hydrophobic-hydrophilic architecture.
Solution Approach 2:
The patent modifies the chemical structure parameters by varying the degree of substitution, side chain length, and crosslinking density to optimize the balance between conductivity and water absorption. Specific parameters like the ratio of hydrophobic to hydrophilic groups are adjusted to control water uptake at elevated temperatures.
2Reliability
If anion exchange membranes are used to achieve high conductivity, then conductivity is improved, but chemical stability deteriorates in severe basic conditions
Solution Approach 1:
The patent uses composite structures with chemically stable poly(ether sulfone) backbones and strategically positioned quaternary ammonium groups. The incorporation of hydrophobic side chains and crosslinking creates a stable matrix that resists degradation in severe basic conditions while maintaining conductivity pathways.
Solution Approach 2:
The patent creates local regions with different properties: stable hydrophobic domains provide chemical resistance while hydrophilic channels maintain conductivity. The quaternary ammonium groups are strategically positioned to ensure stability in basic conditions while preserving ion exchange functionality.
3Duration of action of stationary object
If ionomer is washed out continuously leading to poor chemical stability, then membrane durability is improved, but conductivity decreases
Solution Approach 1:
The patent employs composite structures where the ionomer is integrated into a stable polymeric matrix through grafting and crosslinking. This prevents washout and ensures long-term durability while maintaining continuous conductive pathways for ion transport.
Solution Approach 2:
The patent uses crosslinking agents and coupling agents as intermediaries to bond the ionomer to the membrane matrix. This intermediary bonding prevents ionomer washout while preserving the conductive properties necessary for membrane functionality.
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
Crosslinking enhances thermal and mechanical stability, reduces water swelling, and prevents membrane dissolution, thereby improving the performance and reliability of AEMs.
Implementation Method 1
Crosslinking can be accomplished by heat, UV or IR post treatment; or chemically by adding agents, within the empty space of the substrate medium or a combination of methods
Implementation Method 2
Crosslinking can be accomplished by heat, UV or IR post treatment
Implementation Method 3
Crosslinking can be accomplished by heat, UV or IR post treatment
Implementation Method 4
Crosslinking can be accomplished by heat, UV or IR post treatment
Data Source
AI summary
An ion exchange membrane is provided which includes an ion exchange polymer that is partially cross-linked. The partially cross-linked ion exchange polymer will be more stable and will not be washed out over time. The ion exchange polymer may be UV or chemically cross-linked, wherein a cross-linking compound is added to the ion exchange polymer either before or after coupling to a support material. A support material may be made of, or be coated with, a cross-linking compound and the support material may initiate cross-linking proximal to the support material. The support material may be made of a material that chemically bonds with the ionomer.