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Microblock ionomers: a new concept in high temperature, swelling-resistant membranes for PEM fuel cells

Zhu, Z., Walsby, N.M., Colquhoun, H.M., Thompsett, D. and Petrucco, E. (2009) Microblock ionomers: a new concept in high temperature, swelling-resistant membranes for PEM fuel cells. Fuel Cells, 9 (4). pp. 305-317. ISSN 1615-6846

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To link to this article DOI: 10.1002/fuce.200800140

Abstract/Summary

A novel series of polyaromatic ionomers with similar equivalent weights but very different sulphonic acid distributions along the ionomer backbone has been designed and prepared. By synthetically organising the sequence-distribution so that it consists of fully defined ionic segments (containing singlets, doublets or quadruplets of sulphonic acid groups) alternating strictly with equally well-defined nonionic spacer segments, a new class of polymers which may be described as microblock ionomers has been developed. These materials exhibit very different properties and morphologies from analogous randomly substituted systems. Progressively extending the nonionic spacer length in the repeat unit (maintaining a constant equivalent weight by increasing the degree of sulphonation. of the ionic segment) leads to an increasing degree of nanophase separation between hydrophilic and hydrophobic domains in these materials. Membranes cast from ionomers with the more highly phase-separated morphologies show significantly higher onset temperatures for uncontrolled swelling in water. This new type of ionomer design has enabled the fabrication of swelling-resistant hydrocarbon membranes, suitable for fuel cell operation, with very much higher ion exchange capacities (>2 meq g(-1)) than those previously reported in the literature. When tested in a fuel cell at high temperature (120 degrees C) and low relative humidity (35% RH), the best microblock membrane matched the performance of Nafion 112. Moreover, comparative low load cycle testing of membrane -electrode assemblies suggests that the durability of the new membranes under conditions of high temperature and low relative humidity is superior to that of conventional perfluorinated materials.

Item Type:Article
Refereed:Yes
Divisions:Faculty of Life Sciences > School of Chemistry, Food and Pharmacy > Department of Chemistry
ID Code:11726
Uncontrolled Keywords:High Temperature PEMFC, Hydrocarbon Membrane, Ionomer Membrane , PROTON-EXCHANGE MEMBRANES, SULFONIC-ACID GROUPS, LOW RELATIVE-HUMIDITY, TRANSPORT-PROPERTIES, END-GROUPS, COPOLYMERS, CONDUCTIVITY, SEQUENCE, SIMULATIONS, CONDUCTORS
Additional Information:1st International Conference on Progress in MEA Components for Medium and High Temperature Polymer Electrolyte Fuel Cells 21-24 Sep 2008 La Grande Motte, FRANCE

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