Low equivalent weight ionomer
AssigneeGore Enterprise Holdings, Inc.
InventorsHuey Shen Wu, Charles W. Martin, Xin Kang Chen
Life of this patent
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Abstract
An ionomer and a process for forming the ionomer such that the ionomer has (1) low equivalent weight (below 950, preferably between 625 and 850, and most preferably between 675 and 800) and (2) high conductivity (greater than 0.13 S/cm). In another embodiment, the invention is an ionomer having (1) low equivalent weight (below 950, preferably between 625 and 850, and most preferably between 675 and 800) and (2) acceptably low hydration (less than about 120 weight percent). These ionomers are capable of being processed into thin film and are extremely well-suited for low humidity or high temperature fuel cell applications.
Claims92
A fluorinated ionomer comprising a substantially fluorinated backbone with pendant groups attached thereto, said pendant groups represented by the formula
- 3
- where X is F, Cl or Br or mixtures thereof;
- n is an integer equal to one or two;
- Rf and Rf′ are independently selected from the group of F, Cl, perfluoroalkyl radical, and chloroperfluoroalkyl radical;
- Y is an acid group or a functional group convertible to acid group;
- a is zero or an integer greater than zero;
- and b is an integer greater than zero;
- wherein said ionomer has an equivalent weight between about 600 and about 950;
- and wherein said ionomer has a room temperature ionic conductivity of greater than about 0.13 S/cm when measured on an acid form of a membrane of said ionomer.
A process for making a fluorinated polymer comprising the steps of:
- a) forming a mini-emulsion of a mixture of deionized water, a perfluorinated surfactant, optionally dissolved in an aqueous solution, a liquid perfluorinated hydrocarbon having a molecular weight below 2000 and an ionomeric monomer;
- b) pressurizing said emulsion in an agitated reactor with at least one substantially fluorinated alkene gas;
- c) initiating polymerization with a free radical initiator in said reactor;
- d) maintaining a known pressure of the substantially fluorinated alkene gas for a period of time;
- and
- e) recovering said fluorinated polymer.
A product produced by a process comprising the steps of:
- a) forming a mini-emulsion of a mixture of deionized water, a perfluorinated surfactant, optionally dissolved in an aqueous solution, a liquid perfluorinated hydrocarbon having a molecular weight below 2000 and an ionomeric monomer;
- b) pressurizing said emulsion in an agitated reactor with at least one substantially fluorinated alkene gas;
- c) initiating polymerization with a free radical initiator in said reactor;
- and
- d) maintaining a known pressure of the substantially fluorinated alkene gas for a period of time.
A fluorinated ionomer comprising a substantially fluorinated backbone with pendant groups attached thereto, said pendant groups represented by the formula
- 4
- where X is F, Cl or Br or mixtures thereof;
- n is an integer equal to one or two;
- Rf and Rf′ are independently selected from the group of F, Cl, perfluoroalkyl radical, and chloroperfluoroalkyl radical;
- Y is an acid group or an acid derivative easily converted to an acid group;
- a is zero or an integer greater than zero;
- and b is an integer greater than zero;
- wherein said ionomer has an equivalent weight between about 700 and about 900 and a degree of hydration at room temperature that is less than about 50%.
A fluorinated ionomer comprising a substantially fluorinated backbone with pendant groups attached thereto, said pendant groups represented by the formula
- 5
- where X is F, Cl or Br or mixtures thereof;
- n is an integer equal to one or two;
- Rf and Rf′ are independently selected from the group of F, Cl, perfluoroalkyl radical, and chloroperfluoroalkyl radical;
- Y is an acid group or an acid derivative easily converted to an acid group;
- a is zero or an integer greater than zero;
- and b is an integer greater than zero;
- wherein the equivalent weight is below about 700 and the degree of hydration is less than about 200% at room temperature.
Dependencies are inferred from the claim text.