Thermodynamics, microstructure and interfacial effects in hydrated nafion

Viatcheslav Freger

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

1 Scopus citations

Abstract

Hydration of Nafion is known to profoundly effect its performance, however, measurements of hydration and its modeling and relation to other characteristics have been subject to puzzling controversies such as Schroeder's paradox. This chapter analyzes Nafion hydration based on a new model that consistently relates hydration to microstructure. The hydration equilibrium is interpreted as a balance of 3 pressures: osmotic, elastic and a special interfacial-elastic Laplace pressure, which clarifies the role of relaxation and the origin of non-equilibrium phenomena such as Schroeder's paradox. The predicted structural variation of microstructure with hydration shows a good agreement with available data. The model is also used to analyze microstructure and orientation of Nafion micelles in the surface region exposed to different environments. The predicted variations of surface structure in vapor and water fully agree with GISAXS, AFM and contact angle measurements for Nafion membranes and thin films on different substrates. The external medium and substrate are shown to strongly affect the orientation of micelles in their vicinity. This suggests attractive possibilities of enhancing transport characteristics of Nafion.

Original languageEnglish
Title of host publicationPolymers for Energy Storage and Delivery
Subtitle of host publicationPolyelectrolytes for Batteries and Fuel Cells
PublisherAmerican Chemical Society
Pages283-303
Number of pages21
ISBN (Print)9780841226319
DOIs
StatePublished - 1 Jan 2012
Externally publishedYes

Publication series

NameACS Symposium Series
Volume1096
ISSN (Print)0097-6156
ISSN (Electronic)1947-5918

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