Structure and Properties of Polymer Electrolyte Membranes Containing Phosphonic Acids for Anhydrous Fuel Cells
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- 作者：Sung-Il Lee ; Kyung-Hwan Yoon ; Myeongsoo Song ; Huagen Peng ; Kirt A. Page ; Christopher L. Soles ; Do Y. Yoon
- 刊名：Chemistry of Materials
- 出版年：2012
- 出版时间：January 10, 2012
- 年：2012
- 卷：24
- 期：1
- 页码：115-122
- 全文大小：368K
- 年卷期：v.24,no.1(January 10, 2012)
- ISSN：1520-5002
文摘
Recently, water-free, proton-conducting polymer electrolytes have been attracting attention because of their possible application as fuel cell membranes at intermediate temperatures (100 to 200 掳C). Phosphonic acid groups are considered feasible anhydrous proton conducting moieties due to the high degree of proton self-dissociation arising from their intrinsic amphoteric character and high mobility of protonic charge carriers. In this work, we have synthesized and characterized model, phosphonic acid-functionalized proton-conducting polymers, poly(vinylbenzyloxy-alkyl-phosphonic acid)s, for the purpose of exploring the relationship between molecular design, nanostructure, and performance characteristics. These novel proton conducting materials were characterized for their thermal stability, nanostructure, and performance properties. Thermogravimetric analysis (TGA) indicates that the polymers are thermally stable up to 140 掳C, where the condensation of phosphonic acid groups starts to occur. Results from small-angle X-ray scattering (SAXS) show a peak corresponding to a Bragg spacing of approximately 21鈥?4 脜, which is attributed to layerlike structure formation of the phosphonic acid containing conducting channels. The proton conductivity increases with temperature, reaching a value on the order of 3 脳 10鈥? S/cm at 140 掳C under nominally anhydrous conditions.