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Imidazolium-Based Polymeric Materials as Alkaline Anion-Exchange Fuel Cell MembranesPolymer electrolyte membranes that conduct hydroxide ions have potential use in fuel cells. A variety of polystyrene-based quaternary ammonium hydroxides have been reported as anion exchange fuel cell membranes. However, the hydrolytic stability and conductivity of the commercially available membranes are not adequate to meet the requirements of fuel cell applications. When compared with commercially available membranes, polystyrene-imidazolium alkaline membrane electrolytes are more stable and more highly conducting. At the time of this reporting, this has been the first such usage for imidazolium-based polymeric materials for fuel cells. Imidazolium salts are known to be electrochemically stable over wide potential ranges. By controlling the relative ratio of imidazolium groups in polystyrene-imidazolium salts, their physiochemical properties could be modulated. Alkaline anion exchange membranes based on polystyrene-imidazolium hydroxide materials have been developed. The first step was to synthesize the poly(styrene-co-(1-((4-vinyl)methyl)-3- methylimidazolium) chloride through a free-radical polymerization. Casting of this material followed by in situ treatment of the membranes with sodium hydroxide solutions provided the corresponding hydroxide salts. Various ratios of the monomers 4-chloromoethylvinylbenzine (CMVB) and vinylbenzine (VB) provided various compositions of the polymer. The preferred material, due to the relative ease of casting the film, and its relatively low hygroscopic nature, was a 2:1 ratio of CMVB to VB. Testing confirmed that at room temperature, the new membranes outperformed commercially available membranes by a large margin. With fuel cells now in use at NASA and in transportation, and with defense potential, any improvement to fuel cell efficiency is a significant development.
Document ID
20120013235
Acquisition Source
Jet Propulsion Laboratory
Document Type
Other - NASA Tech Brief
Authors
Narayan, Sri R.
(California Inst. of Tech. Pasadena, CA, United States)
Yen, Shiao-Ping S.
(California Inst. of Tech. Pasadena, CA, United States)
Reddy, Prakash V.
(Missouri Univ. of Science and Technology Rolla, MO, United States)
Nair, Nanditha
(Missouri Univ. of Science and Technology Rolla, MO, United States)
Date Acquired
August 26, 2013
Publication Date
August 1, 2012
Publication Information
Publication: NASA Tech Briefs, August 2012
Subject Category
Man/System Technology And Life Support
Report/Patent Number
NPO-46457
Distribution Limits
Public
Copyright
Public Use Permitted.
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