Carbosilane Cationic Polymers for Tough, Processable AEM Membranes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current anion exchange membranes (AEMs) based on polymers with pendant quaternary ammonium groups are brittle, have low solubility, and are difficult to process, limiting their ion exchange capacity and mechanical properties.
Innovation Solution
Development of cationic polymers with cationic nitrogen-containing groups free of N—H bonds, synthesized via a method involving a precursor polymer, organic silane, and nitrogen-containing base, enabling scalable synthesis, good solubility, and high ion exchange capacity, along with improved mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If polymers with pendant quaternary ammonium groups are used for AEMs, then ion exchange capacity is achieved, but mechanical properties deteriorate (brittle when dry, tear easily when wet)
Solution Approach 1:
The patent changes the chemical structure parameters of the polymer by using carbosilane backbone instead of traditional carbon backbone, and by selecting specific cationic groups without N-H bonds. This structural parameter change enables the polymer to achieve both high ion exchange capacity and improved mechanical properties, resolving the contradiction between quantity of substance and strength.
Solution Approach 2:
The patent creates a composite polymer structure combining carbosilane backbone with pendant cationic groups. This composite approach allows the material to exhibit both the ion exchange capability from the cationic groups and the mechanical stability from the carbosilane framework, simultaneously improving both ion exchange capacity and mechanical properties.
2Quantity of substance
If polymers with pendant quaternary ammonium groups are used for AEMs, then ion exchange function is achieved, but processability deteriorates (low solubility, difficult to process)
Solution Approach 1:
The patent modifies the polymer's solubility parameters by introducing the carbosilane backbone structure and selecting appropriate side chain compositions. These parameter changes enhance solubility and processability while preserving the ion exchange capacity, allowing the material to be easily processed into membranes.
3Quantity of substance
If high ion exchange capacity is achieved in AEMs, then conductivity is improved, but mechanical stability deteriorates
Solution Approach 1:
The patent achieves high ion exchange capacity (up to 3.5 mmol/g) while maintaining mechanical stability through the carbosilane backbone structure. The unique chemical composition parameters of carbosilane provide both high ion exchange capability and exceptional mechanical strength, even at high ion exchange capacities, resolving the contradiction between quantity of substance and reliability.
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 cationic polymers result in AEMs with enhanced ion exchange capacity, conductivity, and mechanical stability, facilitating their use in electrochemical devices such as fuel cells and electrolyzers.
Implementation Method 1
reacting the precursor polymer comprising monomeric units of Formula (I) with an organic silane of Formula (II) to obtain a polymer intermediate comprising monomeric units of Formula (III)
Implementation Method 2
reacting the polymer intermediate comprising monomeric units of Formula (III) with R3, which is a nitrogen-containing base free of any N—H bonds, to obtain a cationic polymer comprising monomeric units of Formula (V)
Implementation Method 3
Anion exchange membranes (AEMs) are useful in various electrochemical cells... cationic polymers having a plurality of cationic groups that can be used to make polymeric membranes, including those that could be used as AEMs with high ion exchange capacities
Data Source
AI summary
Cationic polymers are provided that comprise monomeric units of Formula (V). (V) Each asterisk (*) indicates an attachment position to another monomeric unit; R is hydrogen or methyl; each R2 is each independently an alkyl, aryl, or a combination thereof; L is a linking group comprising an alkylene group; and +R3 is a cationic nitrogen-containing group free of any N—H bonds. Membranes formed from said cationic polymers, devices including such membranes, and methods of making such cationic polymers are also provided.