Blacksburg, Va. -- Fuel cells are well recognized as having real potential to supply clean energy for cars, homes, and portable electronics, such as computers One of the limiting features of fuel cells involve the characteristics and stability of polymeric materials used in the proton exchange membrane (PEM) that allows hydrogen protons (H+ ions) to pass through to the oxygen side of the fuel cell, where it can release electrochemical energy by reaction with the oxygen to produce water.
Existing materials have a reasonable life at 80 degrees C, but experts at the Department of Defense, the Department of Energy, and others have suggested that operation at 120 degrees C or higher would be more efficient.
Virginia Tech researchers will present three approaches for the generation of new PEM materials at the 219th American Chemical Society National Meeting March 26-30 in San Francisco.
The materials being developed by faculty members and students at Virginia Tech have demonstrated better results than existing materials in terms of heat tolerance. The researchers' common approach is to develop PEM wholly aromatic polymers that incorporate the ion conductor sulfonic acid groups at the monomer level rather than during a post reaction, after the polymer has been formed.
"Direct polymerization, or introduction of the ion conductor during a direct reaction from the monomers, instead of a post reaction after polymerization, allows us to develop a better understanding of what the molecular structure is," explains James McGrath, professor of chemistry and director of the Materials Institute at Virginia Tech. "The polymer materials appear to be more stable and better defined when the ion conductor is incorporated during the polymerization, as part of one of the monomers."
The research will be presented at 5:30 p.m. Sunday, March 26, in room 104 of the exhibit level of the Moscone Convention Center. Research on phenyl phosphine oxide -based PEM materials (POLY paper 121) is being presented by chemistry postdoctoral fellows H.K. Shobba and M Sankarapandian, former NSF summer undergraduate researcher Grace Smalley, and McGrath. Research on new polyimides as PEMs (POLY paper 122), which McGrath calls particularly promising, is being presented by chemistry graduate student Nazan Gunduz and McGrath. And research on polysulfones (POLY paper 151) is being presented by post doctoral associates Feng Wang and Qing Ji, Ph.D. students William Harrison and Jeff Mecham, and McGrath, all of Virginia Tech's chemistry department, and Rich Formato and Bob. Kovar of Foster-Miller of Waltham, Mass.
Fuel cell primer:
Oxygen reacts with hydrogen electrochemically to produce water and energy. In a fuel cell, hydrogen protons slip through a proton exchange membrane (PEM) to react with the oxygen in another chamber.
Efficiencies can be higher than an internal combustion engine and many times greater than from batteries. Fuel cells can be smaller, lighter, and less costly than batteries for powering vehicles, with little or no environmental impact.
Fuel cells can also be developed using diesel or regular gasoline, natural gas, or methanol as precursors for the proton exchange.
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