The Department of Energy estimates that oil imports could be reduced by 800,000 barrels per day if only 10 percent of domestic automobiles were powered by fuel cells. NASA has used fuel cells for decades in the U.S. space program. As gasoline and fuel-oil prices climb, the impetus to bring fuel cell technology into everyday use is gaining momentum.
Virginia Tech chemists, among others, will report their progress on developing down-to-earth fuel cell materials during the 220th national meeting of the American Chemical Society Aug. 20-24 in Washington, D.C.
Fuel cells are composed of membranes and catalysts that convert fuel such as hydrogen or methanol to energy, and include collector plates. Proton-exchange membrane (PEM) fuel cells — the most suitable for automotive, home, and computer-power uses because they operate at moderate temperatures — are polymer-based. In hydrogen-powered fuel cells, the polymer membranes critically transports hydrogen protons to allow the overall reaction of hydrogen with oxygen in air to produce energy with environmentally benign water as a byproduct.
One challenge is that polymer properties change with time and temperature, which restricts applications. Chemistry professor James McGrath's research group is developing new PEMs with improved behavior, such as the ability to operate at 110 to 120 degrees C instead of only 80 degrees C.
At the general polymer chemistry session on Wednesday, Aug. 23, the Virginia Tech researchers will give two papers that report on the synthesis of sulfur-containing polymer materials by direct polymerization, which may have the advantage of being stable at higher temperatures, but which have not been examined for PEM use.
Highly sulfonated systems conduct well, but are water soluble; yet the PEM must be insoluble. A paper at 11:10 a.m. "Synthesis and characterization of controlled molecular weight sulfonated aminofunctional poly(arylene ether sulfone)s prepared by direct polymerization (POLY 396)" reports a successful intermediate step to prepare block, or segmented, copolymers as PEM materials, which may improve this situation. Authors are graduate student J.B. Mecham, postdoctoral associate H.K. Shobha, postdoctoral associate Feng Wang, graduate student W.L. Harrison, and McGrath.
The 3:30 p.m. paper describes development of random copolymers for PEM systems that show short term stability up to 220 degrees C for 30 minutes in air and are candidates for 120 to 150 degree C operation. The paper, "Synthesis of sulfonated poly(phenylene sulfide sulfone)s via direct polymerization (POLY 416)," is by Wang, Mecham, Harrison, and McGrath.
Both papers will be given in JW Marriott Hotel Grand Salon I.
The research group will also present three posters about their fuel cell materials research:
Posters being presented at 5:30 p.m. Sunday, Aug. 20, at the Grand Hyatt Hotel Independence Ballroom A are: ß POLY 124 "Influence of bisphenol structure on direct synthesis of sulfonated poly(arylene ether)s," discusses a structural variation of poly(arylene ether)s to identify the most important criteria for PEMs. The research is by Harrison, Wang, Mecham, undergraduate Kerry O'Connor, and McGrath. ß POLY 155 "Sulfonated aromatic diamines as precursors for polyimides for proton exchange membranes," is one of two posters related to the effort of using new thermally stable polyimides. Polyimides are the most thermally stable organic polymer and are widely used in electronics and aerospace. The research report is by Shobha, postdoctoral associate M. Sankarapandian, analytical chemist supervisor T.E. Glass, and McGrath.
The second paper addressing the use of polyimides for PEMs is being presented in the joint polymer/ polymeric materials: science and engineering (PMSE) poster session Thursday, Aug. 24, at 6 p.m. in Convention Center Exhibit Hall D. "Wholly aromatic five- and six-membered ring polyimides containing pendant sulfonic acid functional groups (POLY 355)" is by graduate student Nazan Gunduz and McGrath.
The fuel cell chemistry research began in Virginia Tech's NSF Center for Polymeric Adhesives and Composites and is now being funded by the Office of Naval Research and the Department of Energy in cooperation with Los Alamos National Laboratory. Two of the students, Mike Hickner and William Harrison, are working at Los Alamos this summer and learning important characterization techniques.
PR Contact: Susan Trulove
540-231-5646 strulove@vt.edu