Ionomeric Cross-Linkers for Membrane Mechanical Stability
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Solution Overview
Problem
Existing cross-linkers for polymer membranes, such as divinylbenzene, fail to provide sufficient mechanical stability and ionic capacity, particularly in hydrophilic and anionic membranes, limiting their performance in electrochemical applications like solid acidic electrochemistry.
Innovation Solution
The use of compounds with covalently bonded ionic groups, such as quaternary ammonium, quaternary phosphonium, or tertiary sulphonium groups, as cross-linkers, which are polymerized with vinyl groups to form ionomeric membranes with enhanced mechanical properties and ionic capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If divinylbenzene is used as a cross-linker in anionic membranes, then the membranes can be cross-linked, but the mechanical stability and ionic capacity are insufficient
Solution Approach 1:
The patent changes the chemical parameters of the cross-linker by introducing ionic groups (ammonium, phosphonium, or sulphonium) with specific charge densities. This transforms the cross-linker from a non-ionic hydrocarbon (DVB) to an ionomeric cross-linker that simultaneously provides mechanical strength through covalent bonding and ionic capacity through the charged groups, resolving the contradiction between mechanical stability and ionic capacity.
Solution Approach 2:
The patent creates a composite cross-linker structure that combines organic vinyl groups (for polymerization and mechanical framework) with inorganic-like ionic groups (for ionic conduction). This composite approach allows the single cross-linking agent to fulfill both mechanical and ionic functions that were previously separate requirements.
2Device complexity
If conventional cross-linkers are used, then the membrane structure is simplified, but the performance in electrochemical applications is limited
Solution Approach 1:
The ionomeric cross-linker serves multiple functions simultaneously: it acts as a structural framework builder through vinyl group polymerization, provides ionic conduction pathways through charged groups, and enables both anionic and cationic membrane applications. This multi-functionality improves electrochemical performance without requiring separate components for each function.
3Stability of the object's composition
If hydrophilic polymer membranes are cross-linked with traditional agents, then some stability is achieved, but superior mechanical properties and controlled hydration are not obtained
Solution Approach 1:
The patent introduces ionic groups at specific locations within the cross-linker structure that create localized regions of high charge density. These local ionic clusters attract and organize water molecules, creating controlled hydration zones that simultaneously strengthen the membrane through ion-dipole interactions while maintaining overall compositional stability.
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 ionomeric membranes exhibit superior mechanical properties, increased ionic capacity, and improved hydration control, enabling more efficient and cost-effective alkaline electrolysis compared to conventional solid acidic electrochemistry.
Implementation Method 1
a compound comprising two or more covalently bonded polymerisable vinyl groups and one or more covalently bonded ionic groups... the polymerisation of a compound as defined above
Data Source
AI summary
The present invention is the use of a compound comprising two or more covalently bonded polymerisable vinyl groups and one or more covalently bonded ionic groups selected from a quaternary ammonium group; a quaternary phosphonium group; or a tertiary sulphonium group, as an ionic cross-linker. The cross-linkers of the invention may be used to form an ionomer membrane. Methods for forming the cross-linkers of the invention are also disclosed.