Sulfonic Acid Polymer Membranes With Low Hydrogen Permeability
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Solution Overview
Problem
Current polymers used in polymer electrolyte fuel cells and chlor-alkali electrolysis struggle to achieve a balance between high ion exchange capacity, low hydrogen permeability, and a suitable softening temperature, which is essential for efficient power generation and mechanical strength.
Innovation Solution
A sulfonic acid group-containing polymer with specific units based on tetrafluoroethylene, designed to have a softening temperature between 120 to 140°C and low hydrogen gas permeability, is developed, along with a method to produce it by converting fluorosulfonyl groups to sulfonic acid groups, and a liquid composition incorporating this polymer for membrane formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ion exchange capacity is increased to improve ion conductivity, then the power generation performance is improved, but the softening temperature becomes too high requiring high-temperature heat treatment
Solution Approach 1:
The patent changes the chemical structure parameters of the polymer by introducing specific fluorinated side chains with sulfonic acid groups at controlled positions. This modifies the polymer's physical properties including softening temperature and ion exchange capacity, achieving both high ion conductivity and appropriate softening temperature through structural parameter optimization
Solution Approach 2:
The patent creates a composite polymer structure combining fluorinated backbone with sulfonic acid-containing side chains. This composite approach allows the polymer to exhibit both high ion exchange capacity from the sulfonic acid groups and controlled softening temperature through the fluorinated structure, resolving the contradiction between these two properties
2Ease of operation
If the softening temperature is decreased to improve handling efficiency, then the mechanical strength becomes inferior
Solution Approach 1:
The patent optimizes the polymer structure by controlling the length and position of fluorinated side chains containing sulfonic acid groups. This structural parameter adjustment achieves a softening temperature in the optimal range of 120-140°C, balancing handling efficiency and mechanical strength for practical applications
3Reliability
If the ion exchange capacity is increased to improve power generation performance, then the hydrogen permeability increases
Solution Approach 1:
The patent introduces sulfonic acid groups at specific local positions on fluorinated side chains rather than throughout the entire polymer structure. This localized placement of ion-exchange groups achieves high ion exchange capacity while maintaining low hydrogen permeability through the fluorinated backbone structure, resolving the contradiction between power generation performance and hydrogen barrier properties
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 polymer achieves high ion exchange capacity, low hydrogen permeability, and appropriate softening temperature, enhancing the performance and durability of polymer electrolyte membranes and fuel cells.
Implementation Method 1
fluorosulfonyl groups in a fluorosulfonyl group-containing polymer having units based on a monomer having two fluorosulfonyl groups and units based on tetrafluoroethylene in one molecule, have been converted to sulfonic acid groups
Data Source
AI summary
To provide a sulfonic acid group-containing polymer which is capable of forming a low hydrogen permeable membrane, which shows a high ion exchange capacity, and which shows a proper softening temperature. The sulfonic acid group-containing polymer has units u1 represented by the following formula u1, units u2 represented by the following formula u2, and units u3 based on tetrafluoroethylene,in the formula u1, RF1 and RF2 are each independently a C1-3 perfluoroalkylene group, and Z+ is a hydrogen ion, a metal ion, or an ammonium ion,—[CF2—CF(CF2O—Rf1)]— Formula u2in the formula u2, Rf1 is a perfluoroalkyl group which may contain a SO3−Z+ group and/or an etheric oxygen atom.