Document Type

Article

Publication Date

12-2003

Publication Title

Journal of the Electrochemical Society

Abstract

A physicochemical model is proposed to describe sorption in proton-exchange membranes (PEMs), which can predict the complete isotherm as well as provide a plausible explanation for the long-unresolved phenomenon termed Schroeder’s paradox, namely, the difference between the amounts sorbed from a liquid solvent vs. from its saturated vapor. The solvent uptake is governed by the swelling pressure caused within the membrane as a result of stretching of the polymer chains upon solvent uptake, [formula] as well as a surface pressure, [Formula] due to the curved vapor-liquid interface of pore liquid. Further, the solvent molecules in the membrane are divided into those that are chemically, or strongly, bound to the acid sites, [Formula] and others that are free to physically equilibrate between the fluid and the membrane phases, [Formula] The model predicts the isotherm over the whole range of humidities satisfactorily and also provides a rational explanation for the Schroeder’s paradox.

Volume

150

Issue

12

First Page Number

E601

Last Page Number

E607

DOI

10.1149/1.1623495

Publisher Statement

© The Electrochemical Society, Inc., 2003. All rights reserved. Except as provided under U.S. copyright law, this work may not be reproduced, resold, distributed, or modified without the express permission of The Electrochemical Society (ECS). The archival version of this work was published in Journal of the Electrochemical Society 150 (12), E601-E607.

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