Next-generation energy devices like fuel cells and water electrolyzers depend on ion-exchange membranes that allow only water and certain ions to pass through.
The design of these membranes affects how efficient these devices can be. Understanding how the materials used in them influence their performance is key to advancing these technologies.
At the University of Chicago Pritzker School of Molecular Engineering (UChicago PME), researchers collaborated with scientists at New York University to study the backbone chemistry of different types of ion-exchange membranes to better understand how their chemical makeup governs their structure and performance.
They found that the nanostructures within these membranes evolve when water passes through and are affected by the stiffness of the polymer backbone. Different backbone architectures promote distinct ionic nanostructures, which govern how water is distributed within the membrane. Flexible backbones achieve higher ion conductivity with less water uptake, overcoming a trade-off that has long challenged membrane design.
The results were published in the Journal of the American Chemical Society.
"The combination of experiment and molecular simulation is key to developing a fundamental understanding of these materials and the molecular-level connections," said professor Paul Nealey, who co-authored the research.
Flexibility of backbone overcomes trade-off in performance
Ion-exchange membranes developed for energy devices must be both durable and highly conductive.
In these devices, the goal is often to improve conductivity while controlling water uptake, which in turn controls mechanical stability.
Engineers have created several types of membranes with different polymer backbones. Anion-conducting polyelectrolytes (ACPs) are positively charged polymers that allow negatively charged ions to move along the polymer chains within the membrane.
In this study, the research team synthesized and studied three kinds of ACPs with different backbone architectures, one of which was provided by the Kohl group at the Georgia Institute of Technology. Importantly, they used hydrocarbon-based polymers. Traditionally, these membranes have been developed with fluoropolymers, but engineers are moving toward greener materials for these devices.
"These hydrocarbon materials are very promising, both from an environmental perspective and from a stability standpoint," said Mincheol Kim, a UChicago PME graduate student who led the work. "But we still need fundamental research on them to better understand how they work."
Using both experiments and molecular dynamics simulations, the team found that nanostructures form within the membranes created with these hydrocarbon backbones and then evolve when water passes through.
The molecular simulations, led by Ge Sun, a co-first author now at the Courant Institute School of Mathematics, Computing, and Data Science at NYU, and professor Juan de Pablo, now executive dean of the NYU Tandon School of Engineering, provided atomic-resolution insight into structural differences that experiments alone could not reveal.
Well-defined nanostructures promote more ion-conducting pathways without excessive water uptake—an understanding that could help designers create membranes where less overall water content is key.
"Rather than identifying a single optimal backbone, our work establishes design principles," Kim said. "Different backbone chemistries create different ionic nanostructures, and those nanostructures determine how much water the membrane actually needs to transport ions efficiently."
Next, the team will continue to study how counterion identity influences water dynamics and morphology within these membranes.
"This work offers molecular-level design guidelines for next-generation ACPs," said associate professor Shrayesh Patel, who co-authored the research. "This is the beginning of helping design more environmentally friendly membranes broadly relevant to energy conversion, separations and critical minerals recovery."
Publication details
Mincheol Kim et al, Origins of Enhanced Ion Transport in Nanostructured Anion-Conducting Polyelectrolytes, Journal of the American Chemical Society (2026). DOI: 10.1021/jacs.6c05179
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Citation: Membrane nanostructures reshape in water, revealing route to better ion transport (2026, July 27) retrieved 28 July 2026 from https://phys.org/news/2026-07-membrane-nanostructures-reshape-revealing-route.html
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