Controlling Polymer Electrolyte Interfacial Morphology through Chemical Interactions

Published

September 9, 2025

Author(s)

Joseph Dura, Sangcheol Kim, Kirt Page, Christopher Soles

Abstract

Owing to its unique mechanical properties, chemical resistance, and ion conductivity, Nafion is one of the most widely used polymer electrolytes. In hydrogen fuel cells, it constitutes both the macroscopic membrane separating the anode and the cathode, and as a thin film, Nafion appears as a binder in the catalyst layer where conductive ionic pathways must intimately interface with platinum catalyst particles, electrically conductive carbon particles, and porous surfaces that facilitate the transport of gases. Residing at the intersection of this diverse range of materials, the ionomer's interfacial structure influences interfacial impedance and thus device performance. This interface structure has been widely investigated on model surfaces with neutron reflectometry and other techniques, resulting in the discovery of a multilamellar structure at the interface with hydrophilic materials, or a single water-rich layer at the interface with, e.g., metals, favoring tangential vs perpendicular ion transport, respectively. Here we demonstrate that self-assembled monolayers, SAMs, which can coat various surfaces, can control whether single or multiple lamellae occur. These interfacial structures can be further modified through acid−base interactions by protonating the terminal amine group of a SAM at low pH. This establishes a methodology to control the interfacial ionic transport pathways in Nafion and determine the interfacial impedance.

Citation

Chemistry of Materials

Volume

37

Issue

17

Pub Type

Journals

Download Paper

https://doi.org/10.1021/acs.chemmater.5c01738

Local Download

Keywords

Nafion, polymer electrolyte, fuel cell, interfacial structure, ion transport, self-assembled monolayer, neutron reflectometry

Citation

Dura, J. , Kim, S. , Page, K. and Soles, C. (2025), Controlling Polymer Electrolyte Interfacial Morphology through Chemical Interactions, Chemistry of Materials, [online], https://doi.org/10.1021/acs.chemmater.5c01738, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=959039 (Accessed October 17, 2026)

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