Crosslinked SEBS Anion Exchange Membranes With Lower Water Uptake

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Solution Overview

Problem

Existing anion exchange membranes (AEMs) degrade easily under high alkaline conditions due to strong interaction of ionic side groups with water, leading to polymer softening and swelling.

Innovation Solution

A crosslinked polymer network is formed using functionalized poly(styrene-b-ethylene-r-butylene-b-styrene) triblock copolymers with saturated benzylic alkyl groups and diamine linkers, allowing for simultaneous quaternization and crosslinking, resulting in reduced water uptake and enhanced stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If ionic side groups (quaternary ammonium groups) are introduced to enable anion exchange, then ion exchange capacity is improved, but polymer stability deteriorates due to strong interaction with water causing softening and swelling

Engineering Contradiction:

Improveion exchange capacityVSAvoidpolymer stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent segments the polymer structure into distinct functional regions: hydrophobic aromatic backbone segments provide structural stability, while ionic side groups are segregated into specific locations along the backbone. This segmentation allows the stable aromatic core to maintain polymer integrity while the distributed ionic groups provide ion exchange capacity without concentrating water interaction in one location.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies local quality by creating regions with different properties along the polymer chain. The aromatic backbone provides rigid, water-resistant regions for structural stability, while localized ionic side groups provide ion exchange functionality. This spatial differentiation of properties allows simultaneous achievement of stability and ion exchange capacity.

Inventive Principle:

Principle #3Local quality

2Reliability

If ionic side groups interact strongly with water to enable ion transport, then ion exchange function is improved, but polymer mechanical properties worsen due to softening and swelling

Engineering Contradiction:

Improveion exchange functionVSAvoidmechanical strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent creates a composite polymer structure combining aromatic blocks (providing mechanical strength and dimensional stability) with ionic side groups (provid ion exchange function). The aromatic backbone acts as a rigid framework that maintains mechanical properties while the attached ionic groups provide water-compatible ion transport, effectively combining materials with complementary properties.

Inventive Principle:

Principle #40Composite materials

3Ease of manufacture

If polymer chains are left uncrosslinked to maintain flexibility, then ease of manufacture is improved, but durability under hydrated conditions deteriorates

Engineering Contradiction:

Improveprocessing simplicityVSAvoiddurability under hydration

Core Design Contradiction:

Ease of manufactureVSDuration of action of stationary object

Solution Approach 1:

The patent incorporates crosslinkable functional groups (such as epoxide or vinyl groups) into the polymer structure during synthesis, but the actual crosslinking reaction is triggered later under controlled conditions. This preliminary preparation allows easy manufacturing of the precursor polymer, while subsequent crosslinking provides enhanced durability under hydrated conditions without complicating the initial manufacturing process.

Inventive Principle:

Principle #10Preliminary action

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 crosslinked polymer network exhibits improved durability and stability under hydrated conditions while maintaining ion exchange capacity, suitable for applications in fuel cells, water electrolysis, batteries, and other electrochemical devices.

Implementation Method 1

crosslinking the functionalized aromatic block copolymer with another functionalized aromatic block copolymer via the diamine to create a crosslinked polymer

Methodology Applied

Scientific EffectChemical Bonding: Chemical Bonding

Implementation Method 2

AEMs allow transportation of anions, e.g., OH−, Cl−, Br−, etc., from a cathode to an anode in electrochemical reaction

Methodology Applied

Scientific EffectIon Exchange: Ion Exchange

Data Source

PatentUS20260062547A1Crosslinking of aromatic polymers for anion exchange membranes

Publication Date: 2026.03.05 RENESSELAER POLYTECHNIC INST

AI summary

An ion exchange membrane material is composed of a crosslinked polymer network including a first poly(styrene-b-ethylene-r-butylene-b-styrene) triblock copolymer (SEBS), and second SEBS, and a linker crosslinking the first SEBS and the second SEBS. At least one phenyl group from the first SEBS and the second SEBS is functionalized with an alkyl group, and the carbon at the benzylic position of these alkyl groups is saturated with at least two additional alkyl groups. The linker is a diamine bound to the alkyl functional groups. The ion exchange membrane material is made via a substantially simultaneous quaternization and crosslinking reaction between the diamine linker and SEBS functionalized with alkyl halide groups. Increasing concentration of crosslinker produces membranes with reduced water uptake, leading to an expectation of enhanced stability under hydrated conditions and greater durability. Advantageously, this reduction in water uptake came with little change to ion exchange capacity.