Ether-Free Hydrocarbon Proton Exchange Membrane

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Solution Overview

Problem

Conventional hydrocarbon-based proton exchange membranes are not chemically stable in highly acidic conditions and struggle to match the proton conductivity of expensive perfluorinated membranes like Nafion, especially at low relative humidity levels, making them unsuitable for various applications such as fuel cells and water hydrolysis.

Innovation Solution

A polymeric material with a substantially ether-free polyaryl main chain and strongly acidic hydrocarbon side chains, which creates a phase-separated morphology for enhanced proton and water transport, including a biphenyl group and fluoroalkyl sulfonate groups, providing chemical stability and proton conductivity comparable to Nafion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If hydrocarbon-based polymers with aryl-ether linkages are used, then cost is reduced compared to perfluorinated membranes, but chemical stability deteriorates in highly acidic conditions

Engineering Contradiction:

ImprovecostVSAvoidchemical stability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent removes ether linkages from the polymer backbone structure, extracting the problematic component that causes chemical instability in acidic conditions while retaining the hydrocarbon-based cost advantage

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent creates a composite structure combining a hydrophobic polyaryl backbone with hydrophilic side chains containing acidic groups, achieving both chemical stability and proton conductivity in a single material system

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If hydrocarbon-based polymers are used, then cost is reduced, but proton conductivity deteriorates at low relative humidity levels

Engineering Contradiction:

ImprovecostVSAvoidproton conductivity

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent introduces localized hydrophilic regions with acidic side chains within the hydrophobic polymer matrix, creating local pathways for proton transport that maintain conductivity at low humidity while preserving the overall hydrocarbon-based structure

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent combines hydrophobic polyaryl backbone segments with hydrophilic side chain segments containing acidic groups, creating a composite material that exhibits both cost advantage and maintained proton conductivity across varying humidity conditions

Inventive Principle:

Principle #40Composite materials

3Reliability

If perfluorinated membranes like Nafion are used, then proton conductivity is improved, but cost increases and adaptability to certain applications deteriorates

Engineering Contradiction:

Improveproton conductivityVSAvoidcost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replicates the successful phase-separated morphology and proton transport mechanism of perfluorinated membranes like Nafion, but implements them using cheaper hydrocarbon-based polymers without ether linkages

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The patent changes the chemical composition parameters from perfluorinated to hydrocarbon-based polymers, and from ether-linked to ether-free structures, while maintaining the functional performance parameters of proton conductivity and chemical stability

Inventive Principle:

Principle #35Parameter changes

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 material maintains mechanical stability and proton conductivity even at low humidity, outperforming Nafion in cost-effectiveness and adaptability for diverse applications like fuel cells, redox flow batteries, and hydrogen compressors.

Implementation Method 1

The hydrophobic and hydrophilic regions on the polymer create a phase-separated morphology that affords enhanced transport of protons and water across the membrane

Methodology Applied

Scientific EffectPhase separation:

Implementation Method 2

The main chain is substantially hydrophobic while acidic groups in the acidic side chains are substantially hydrophilic

Methodology Applied

Scientific EffectHydrophobic-hydrophilic interaction:

Data Source

PatentUS11621433B2Proton exchange membrane material and methods of making the same

Publication Date: 2023.04.04 RENESSELAER POLYTECHNIC INST

AI summary

Hydrocarbon proton exchange membranes are disclosed that are composed of a material including a hydrophobic main chain, and acidic side chains. The main chain includes a polyaryl structure that is substantially free of ether linkages and also includes a fluoromethyl substituted carbon. The acidic side chains include a hydrocarbon tether terminated by a strongly acidic group, such as a fluoroalkyl sulfonate group. Chemical stability of the material is increased by removing the ether linkages from the main chain. The hydrophobic main chain and substantially hydrophilic side chains create a phase-separated morphology that affords enhanced transport of protons and water across the membrane even at low relative humidity levels. These materials are advantageous as membranes for use in fuel cells, redox flow batteries, water hydrolysis systems, sensors, electrochemical hydrogen compressors, actuators, water purifiers, gas separators, etc.