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Effect of Ionomer-Solvent Interactions in PFSA Dispersions: Dispersion Viscosity
Melissa Novy1, Denis Duchesne2, Gregg Dahlke2
1Department of Chemistry, Macromolecules Innovation Institute, Virginia Tech, Blacksburg, Virginia 24061, United States.
Macromolecules
|March 2, 2026
Summary
Perfluorosulfonic acid (PFSA) dispersion viscosity is crucial for fuel cell applications. Higher viscosity, influenced by PFSA structure and solvent, impacts coating performance and is linked to aggregate morphology and ionic associations.
Area of Science:
- Materials Science
- Electrochemistry
- Chemical Engineering
Background:
- Perfluorosulfonic acid (PFSA) ionomer dispersions are critical for fabricating components in hydrogen fuel cells and water electrolyzers.
- Dispersion viscosity directly influences coating processes like wetting and leveling, impacting overall device performance.
Purpose of the Study:
- To investigate how PFSA concentration, chemical structure, and solvent composition affect dispersion viscosity.
- To correlate viscosity with colloidal morphology and understand the underlying interactions.
Main Methods:
- Examined five different PFSAs and three binary alcohol-water solvent systems (n-propanol, isopropanol, ethanol).
- Measured zero-shear viscosity (η₀) as a function of PFSA and solvent parameters.
- Analyzed PFSA colloidal morphology and solvent-side chain/backbone interactions.
Main Results:
- Zero-shear viscosity (η₀) increases with decreasing side chain length, increasing side chain content, and higher alcohol concentration.
- Identified two viscosity dependence regimes (weak and strong) on alcohol concentration.
- High alcohol concentrations lead to increased η₀ due to aggregate morphology and ionic associations, linked to unfavorable solvent-side chain interactions.
Conclusions:
- PFSA dispersion viscosity is tunable via PFSA structure and solvent composition.
- Viscosity behavior is governed by a balance of solvent-side chain and solvent-backbone interactions.
- The crossover in viscosity dependence aligns with the shift in dominant solvent-PFSA interactions.
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