Chemical Durability Studies of Perfluorinated Sulfonic Acid Polymers and Model Compounds under Mimic Fuel Cell Conditions

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• 作者：Chun Zhou ; Miguel A. Guerra ; Zai-Ming Qiu ; Thomas A. Zawodzinski ; Jr. ; David A. Schiraldi
• 刊名：Macromolecules
• 出版年：2007
• 出版时间：November 27, 2007
• 年：2007
• 卷：40
• 期：24
• 页码：8695 - 8707
• 全文大小：1611K
• 年卷期：v.40,no.24(November 27, 2007)
• ISSN：1520-5835

文摘

Peroxide radical treatments of a perfluorinated ionomer used in polymer electrolyte membrane(PEM) fuel cells and its small molecule analogues were carried out, along with analysis of the resultant products.Molecules containing terminal carboxylic acids degraded at least 1 order of magnitude faster than noncarboxylatematerials; all of the systems did show peroxide-initiated degradation nonetheless. Product analysis suggests thatterminal carboxylic acids react according to a sequential chain shortening, consistent with previous studies. Cleavageof side chains from both polymer and model compounds was also observed to be important and in fact may bethe dominate pathway in low carboxyl content commercial PEM membranes, based on the following comparisonof reactivity and concentration. The relative reactivities of carboxylic chain ends and ether linkages is approximately500, as calculated using model compounds fluoride generation rates. Commercial perfluorosulfonic acid (PFSA)products contain minimal carboxylic acid end groups, and the side chain concentrations are of 2-3 orders ofmagnitude higher than carboxylic acid end groups.