Grafted functional groups on expanded tetrafluoroethylene (ePTFE) support for fuel cell and water transport membranes

Patent metadata

Field	Value
Publication number	US-9553327-B2
Application number	US-201414586132-A
Country	US
Kind code	B2
Filing date	Dec 30, 2014
Priority date	Dec 30, 2014
Publication date	Jan 24, 2017
Grant date	Jan 24, 2017

Abstract

A method for forming a modified solid polymer includes a step of contacting a solid fluorinated polymer with a sodium sodium-naphthalenide solution to form a treated fluorinated solid polymer. The treated fluorinated solid polymer is contacted with carbon dioxide, sulfur dioxide, or sulfur trioxide to form a solid grafted fluorinated polymer. Characteristically, the grafted fluorinated polymer includes appended CO 2 H or SO 2 H or SO 3 H groups. The solid grafted fluorinated polymer is advantageously incorporated into a fuel cell as part of the ion-conducting membrane or a water transport membrane in a humidifier.

First claim

What is claimed is:

1. A method comprising:
providing a solid fluorinated polymer;
contacting the solid fluorinated polymer with a sodium-naphthalenide solution to form a treated fluorinated solid polymer; and
contacting the treated fluorinated solid polymer with carbon dioxide, sulfur dioxide, or sulfur trioxide to form a solid grafted fluorinated polymer that includes appended CO 2 H or SO 2 H or SO 3 H groups.

2. The method of claim 1 wherein the solid fluorinated polymer is a polymeric membrane.

3. The method of claim 2 wherein the solid fluorinated polymer includes repeating CF 2 —CF 2 groups.

4. The method of claim 2 wherein the solid fluorinated polymer is a perfluorinated polymer.

5. The method of claim 2 wherein the solid fluorinated polymer is porous.

6. The method of claim 5 wherein the solid fluorinated polymer has a void volume from about 10 to about 95 percent.

7. The method of claim 5 wherein the solid fluorinated polymer is an expanded polytetrafluoroethylene.

8. The method of claim 5 further comprising imbibing an ion-conducting polymer into the solid grafted fluorinated polymer to form a supported membrane.

9. The method of claim 8 further comprising incorporating the supported membrane into a fuel cell or a water transfer device.

10. The method of claim 1 wherein the sodium-naphthalenide solution includes sodium-naphthalenide in an amount from about 0.05 to about 1 moles/liter.

Assignees

• Gm Global Tech Operations Llc

Inventors

• Fuller Timothy J
• Jiang Ruichun

Classifications

• H01M8/1088 Primary

  Chemical modification, e.g. sulfonation · CPC title

• H01M8/1067

  characterised by their physical properties, e.g. porosity, ionic conductivity or thickness · CPC title

• C08J2327/18

  Homopolymers or copolymers of tetrafluoroethylene · CPC title

• H01M8/04141

  by water containing exhaust gases · CPC title

• C08J9/224

  Surface treatment · CPC title