Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Reexamination Certificate
2000-02-18
2003-07-01
Hampton-Hightower, P. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
C528S125000, C528S128000, C528S170000, C528S171000, C528S172000, C528S173000, C528S174000, C528S176000, C528S183000, C528S184000, C528S185000, C528S189000, C528S190000, C528S220000, C528S223000, C528S225000, C528S228000, C528S229000, C528S327000, C528S350000, C528S352000, C528S353000
Reexamination Certificate
active
06586561
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a polymeric material particularly adapted for use as a polymer electrolyte membrane in a fuel cell. Specifically, the present invention relates to rigid rod copolyimide polymers containing sulfonic acid groups. More specifically, the present invention relates to a copolyimide containing sulfonic acid constituents, having a rigid rod, liquid crystalline structure, and which incorporates bulky, displacing or angled monomers along the polymer chain. Incorporation of bulky monomers in the polymer chain creates regions of access along the chain, thereby exposing sulfonic acid groups, also located along the chain, which in turn enhances conductivity properties of the polymer.
BACKGROUND OF THE INVENTION
Solid, proton conducting polymer electrolyte membranes (PEMs) provide several key features in present technology fuel cells. These features include providing a conduction medium for protons, supporting and separating electrodes, and separating fuel from oxidizer.
Consequently, polymer electrolyte membranes must exhibit ion exchange properties that allow sufficient conductivities to be achieved. In addition, such membranes must exhibit high chemical and mechanical resistance under extreme operating conditions which are typically encountered in many fuel cell applications.
An example of a commercially available polymer electrolyte membrane is Nafion® and is available from DuPont. Nafion® is adequate for use in most current fuel cell applications, but exhibits several deficiencies. It has poor conductivity at low relative humidities and can not easily be used at temperatures above 80° C. because it dries out. Furthermore, Nafion® exhibits high osmotic drag which contributes to difficulties in water management at high current densities. In addition, high methanol permeability in Nafion® contributes to detrimental fuel cross over, in which fuel passes across the anode, through the Nafion® membrane and to the cathode. Consequently, in instances of fuel cross over, methanol is oxidized at the cathode and fuel cell efficiency decreases.
It would be beneficial to identify polymeric materials suitable for use as polymer electrolyte membranes in a fuel cell that exhibit improved properties over currently available materials. Specifically, it would be desirable to provide a polymeric material that exhibits increased conductivity, improved thermal stability, reduced methanol permeability and improved mechanical properties over presently available polymer electrolyte membranes such as Nafion®.
SUMMARY OF THE INVENTION
The present invention achieves all of the foregoing objectives and provides, in a first aspect, a rigid rod ion conducting copolymer comprising three types of monomers. The first monomer is a generally non-polar monomer that is capable of binding a diamine. The second monomer is a diamine monomer having sulfonic acid groups. The third monomer is either a diamine or a dianhydride and is relatively bulky and capable of reacting with the first or second monomer. The copolymer exhibits liquid crystal behavior.
In another aspect, the present invention provides a polymer particularly adapted for use as a membrane in a fuel cell. The polymer exhibits a certain structure defined herein as either Structure I or II.
In a further aspect, the present invention provides a polymer electrolyte membrane comprising a polymer having either Structure I or II and a particular thickness range.
In an additional aspect, the present invention provides a fuel cell comprising a cathode, an anode, and a polymer electrolyte membrane situated between the cathode and anode. The polymer electrolyte membrane comprises a polymer having a structure defined herein as either Structure I or II.
REFERENCES:
patent: 4390603 (1983-06-01), Kawona et al.
patent: 4849311 (1989-07-01), Itoh et al.
patent: 4973530 (1990-11-01), Vanderborgh et al.
patent: 5126462 (1992-06-01), Greber et al.
patent: 5403675 (1995-04-01), Ogata et al.
patent: 5468574 (1995-11-01), Ehrenberg et al.
patent: 5525436 (1996-06-01), Savinell et al.
patent: 5679482 (1997-10-01), Ehrenberg et al.
patent: 5783324 (1998-07-01), Binder et al.
patent: 5795496 (1998-08-01), Yen et al.
patent: 5798188 (1998-08-01), Mokohyama et al.
patent: 6066710 (2000-05-01), Becker et al.
patent: 6245881 (2001-06-01), Faure et al.
patent: 6376129 (2002-04-01), Faure et al.
patent: 97/42253 (1997-05-01), None
Zhang et al. “Molecular Design Considerations in the Synthesis of High Proton Conducting PEMs for Fuel Cells”.
Wang et al. “A H2/O2Fuel Cell Using Acid Doped Polybenzimidazole As Polymer Electrolyte”Electrochimica Acta., vol. 41, No. 2, 193-197 (1996) no month.
Mosdale et al. “Water Profile Determination in a Running Proton Exchange Membrane Fuel Cell Using Small-angle Neutron Scattering”Journal of Membrane Science, 118, 269-277 (1996) no month.
Wasmus et al. “Methanol Oxidation and Direct Methanol Fuel Cells: a Selective Review”Journal of Electroanalytical Chemistry, 461, 14-31 (1999) no month.
Spiliopoulos et al. “Synthesis of Soluble, Blue-Light-Emitting Rigid-Rod Polyamides and Polyimides Prepared from 2′,6′,3″,5′″-Tetraphenyl-or Tetra(4-Biphenylyl)-4,4′″-diamino-p-quinquephenyl”Macromolecules31, 515-521 (1998) no month.
Faure et al. “Sulfonated Polyimides as Proton Exchange Membrane for H2/O2Fuel Cells” 4th European Technical Symposium on Polyimides and High Performance Polymers, 414-422.
Mercier et al. “Fuel Cell Membranes Based on Polyimide Materials”(abstract) Polycondensation '98 Final Program.
Rusarov et al. “Advances in the Synthesis of Poly(perylene carboximides) and Poly(napthalene carboximides)”Polymer Science, Ser. A, vol. 41, No. 1, 2-21 (1999) no month.
Mikroyannidis. “Rigid-Rod Polyamides and Polyimides Prepared from 4,3″-Diamino-2′,6′-D1(2-naphthyl)-p-terphenyl and 2′,6′,3″,5′″-Tetra (22-naphthyl)-4,4″-Diamino-p-quiquephenyl”Journal of Polymer Science:PartA:Polymer Chemistry, vol. 37, 15-24 (1999) no month.
Mikroyannidis. “Soluble, UV-Fluorescent Polyamides and Polyimides Containing Oligophenyls in the Main Chain and Highly Phenylated Side Groups”Macromal. Chem. Phys., 200, 2327-2331 (1990) no month.
Kreuer. “Proton Conductivity: Materials and Applications”Chem. Mater., 8, 610-641 (1996) no month.
Escribeno et al. “Volumic Electrodes of Fuel Cells with Polymer Electrolyte Membranes: Electrochemical Performances and Structural Analysis by Thermoporometry”Electrochimica Acta, vol. 43, Nos. 14-15, 2195-2202, (1998) no month.
Sakaguchi et al. “Synthesis and Characterization of Aromatic Polyamides Derived from New Phenylated Aromatic Diamines”Polymer Journal, vol. 24, No. 10, 1147-1154 (1992) no month.
Dhar. “On Solid Polymer Fuel Cells”J. Electroanal. Chem., 357, 237-250 (1993) no month.
Prater. “Polymer Electrolyte Fuel Cells: A Review of Recent Developments”Journal of Power Sources, 51, 129-144 (1994).
Litt Morton H.
Savinell Robert F.
Wainright Jesse S.
Zhang Yue
Case Western Reserve University
Fay Sharpe Fagan Minnich & McKee LLP
Hampton-Hightower P.
LandOfFree
Rigid rod ion conducting copolymers does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Rigid rod ion conducting copolymers, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Rigid rod ion conducting copolymers will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3091529