Cross-Linked Polycyclohexadiene (PCHD) Membrane for Fuel Cells

Ref: PD 02041-03

Technical Field

Chemistry                           

The Problem

The polymer exchange membrane fuel cell (PEMFC) is one of the most promising of all emerging fuel cell technologies. This technology is being developed for transport applications as well as for stationary and portable applications. There are two major problems hindering its implementation and commercial success: one is the high cost of existing alternatives, and the other is the effectiveness of the fuel cell membrane in facilitating the reaction. There is a tremendous need for membranes with increased durability and decreased production costs.

The Technology Solution

Recognizing that a more effective fuel cell membrane could revolutionize the fuel cell industry, researchers at the University of Tennessee have developed a cross-linked polycyclohexadiene (PCHD) membrane. Through this novel cross-linking technique, researchers have been able to far exceed previous durability and temperature limits. The resulting membranes are superior to the industry standard in proton conductivity, mechanical flexibility and thermal stability.  They are highly resistant to chemical degradation and, in the lab, production costs are only 7% of the current industry standard, Nafion®.

Benefits

•    Accelerate total market demand for fuel cell applications by providing a much lower cost and more highly durable fuel cell membrane

•    Be the first to market a superior fuel cell membrane for the growing applications of fuel cell technology

•    Very flexible membranes and with mechanical integrity and thermal stability

•    Cost of membrane is about 7% that of Nafion with higher proton conductivity than Nafion

The Inventor

Dr. Jimmy Mays is a professor and distinguished scientist at the University of Tennessee. He received his B.S. in Polymer Science from the University of Southern Mississippi, and his Ph. D. in the same from the University of Akron. Before his joint appointment with Oak Ridge National Laboratory and the University of Tennessee, Dr. Mays was part of the chemistry faculty at the University of Alabama at Birmingham. His research includes synthesis of linear and branched polymers and copolymers of controlled structure, and polymer molecular characterization via dilute solution techniques

Contact

The University of Tennessee Research Foundation (UTRF) is a non-profit corporation responsible for commercializing University of Tennessee technologies and for supporting University research.  UTRF is seeking parties interested in learning more about this technology and in exploring possible research and/or commercialization arrangements.

Ph:  (865) 974-1882

Fax:  (865) 974-2803

E-mail:  utrf@tennesse.edu

Reference:

Abstract:
We propose to investigate the synthesis, properties, and morphology of a range of polymers consisting of fluorinated 1,4-polybutadiene and sulfonated polystyrene.  Hillmyer and co-workers (J. Am. Chem. Soc., 120, 6830, 1998) have reported a facile method for fluorination of polydienes based upon difluorocarbene additon.  This reaction employs the relatively inexpensive hexafluoropropyleme oxide as reagent and does not lead to chain scission or crosslinking. When polybutadiene with high 1,4- microstructure was treated with this reagent, the conversion was quantitiative and the resulting semicrystalline polymer had a tg of 89C, Tm of 150C, and showed good thermal stability ( a sample of similarly fluorinated polyisoprene retained 99.7% of its weight when heated at 200C under nitrogen for 1 hour).   These properties suggest that fluorinated polybutadiene could serve as a promising and low cost alternative matrix material in a Nafion-like ionomer system.
Copolymers of butadiene and styrene may be produced with a range of architectures encompassing diblock, triblock, statistical, and graft copolymers.  When anionic polymerization is employed in the synthesis, well defined structures having controlled molecular weights, compositions, and narrow polydispersities may be synthesized.  After fluorination of the polybutadiene component, the polystyrene segments may be sulfonated using reagents such as acetyl sulfate or sulfur trioxide.  If the content of sulfonated polystyrene in the copolymer is relatively low, a Nafion type structure having a hydrophobic semicrystalline continous phase containing dispersed nanoscale ionic clusters will be generated via self-assembly.  By tuning the composition, molecular weight, and architecture the structue, and thus the properties, may be optimized for specific applications.