Bromine, chlorine or iodine functional polymer electrolytes crosslinked by e-beam

• US 7,265,162 B2
• Filed: 11/13/2003
• Issued: 09/04/2007
• Est. Priority Date: 11/13/2003
• Status: Expired due to Fees

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Hintzer, Klaus, Hamrock, Steven J., Jing, Naiyong, Yandrasits, Michael A., Fukushi, Tatsuo, Lochhaas, Kai Helmut, Thaler, Arne
• Primary Examiner(s): McClendon; Sanza L.
• Application Number:
  US10/712,590
• Publication Number:
  US 20050107490A1
• Time in Patent Office: 1,391 Days
• Field of Search: 522/1, 522/2, 522/150, 522/155, 522/156, 522/184, 522/185, 522/186, 522/187, 522/188, 522/189, 428/421, 428/422, 428/308.4, 52109-112
• US Class Current: 522/156
• CPC Class Codes: B01D 67/009 with wave-energy, particle-radiation or plasma
• CPC Class Codes: B01D 71/32 containing fluorine atoms
• CPC Class Codes: B01D 71/82 characterised by the presence of specified groups, e.g. introduced by chemical after-treatment
• CPC Class Codes: C08F 114/26 Tetrafluoroethene
• CPC Class Codes: C08J 2327/18 Homopolymers or copolymers of tetrafluoroethylene
• CPC Class Codes: C08J 3/28 Treatment by wave energy or particle radiation
• CPC Class Codes: C08J 5/225 containing fluorine
• CPC Class Codes: H01M 2300/0082 Organic polymers
• CPC Class Codes: H01M 8/1023 having only carbon, e.g. polyarylenes, polystyrenes or polybutadiene-styrenes
• CPC Class Codes: H01M 8/1039 halogenated, e.g. sulfonated polyvinylidene fluorides
• CPC Class Codes: H01M 8/1072 by chemical reactions, e.g. insitu polymerisation or insitu crosslinking
• CPC Class Codes: H01M 8/1088 Chemical modification, e.g. sulfonation
• CPC Class Codes: Y02E 60/50 Fuel cells
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

A method is provided for making a crosslinked polymer electrolyte, typically in the form of a membrane for use as a polymer electrolyte membrane in an electrolytic cell such as a fuel cell, as well as the polymer so made, the method comprising application of electron beam radiation to a highly fluorinated fluoropolymer comprising: a backbone derived in part from tetrafluoro-ethylene monomer, first pendent groups which include a group according to the formula —SO₂X, where X is F, Cl, Br, OH or —O⁻M⁺, where M⁺ is a monovalent cation, and second pendent groups which include Br, Cl or I. Typically, the membrane has a thickness of 90 microns or less, more typically 60 or less, and most typically 30 microns or less.

Claims

1. A method of making a crosslinked polymer comprising the steps of:

a) providing a highly fluorinated fluoropolymer comprising;

a backbone derived in part from tetrafluoroethylene monomer, first pendent groups which include a group according to the formula —

SO2X, where X is F, Cl, Br, OH or O-M+, where M+ is a monovalent cation, and second pendent groups which include Br; and

b) exposing said fluoropolymer to electron beam radiation so as to result in the formation of crosslinks.

2. The method according to claim 1 wherein said method additionally comprises, prior to said step b), the step of:

c) forming said fluoropolymer into a membrane.

3. The method according to claim 1 wherein said membrane has a thickness of 90 microns or less.

4. The method according to claim 1 wherein said step of exposing said fluoropolymer to electron beam radiation comprises exposing said fluoropolymer to greater than 1 Mrad of electron beam radiation.

5. The method according to claim 1 wherein said step of exposing said fluoropolymer to electron beam radiation comprises exposing said fluoropolymer to greater than 3 Mrad of electron beam radiation.

6. The method according to claim 1 wherein said step of exposing said fluoropolymer to electron beam radiation comprises exposing said fluoropolymer to greater than 15 Mrad of electron beam radiation.

7. The method according to claim 1 wherein said highly fluorinated fluoropolymer is perfluorinated.

8. The method according to claim 1 wherein said pendent groups are according to the formula R1 SO2X, where R1 is a branched or unbranched perfluoroalkyl or perfluoroether group comprising 1-15 carbon atoms and 0-4 oxygen atoms, and where X is F, Cl, Br, OH or O-M+, where M+ is a monovalent cation.

9. The method according to claim 1 wherein said pendent groups are groups according to the formula —

O—

(CF2)4-SO2X, where X is F, Cl, Br, OH or O-M+, where M+ is a monovalent cation.

10. The method according to claim 1 wherein said pendent groups are groups according to the formula —

O—

(CF2)4-SO3H.

11. The method according to claim 2 wherein said pendent groups are according to the formula R1 SO2X, where R1 is a branched or unbranched perfluoroalkyl or perfluoroether group comprising 1-15 carbon atoms and 0-4 oxygen atoms, and where X is F, Cl, Br, OH or O-M+, where M+ is a monovalent cation.

12. The method according to claim 2 wherein said pendent groups are groups according to the formula —

O—

(CF2)4-SO2X, where X is F, Cl, Br, OH or O-M+, where M+ is a monovalent cation.

13. The method according to claim 2 wherein said pendent groups are groups according to the formula —

O—

(CF2)4-SO3H.

14. The method according to claim 3 wherein said pendent groups are according to the formula R1 SO2X, where R1 is a branched or unbranched perfluoroalkyl or perfluoroether group comprising 1-15 carbon atoms and 0-4 oxygen atoms, and where X is F, Cl, Br, OH or O-M+, where M+ is a monovalent cation.

15. The method according to claim 3 wherein said pendent groups are groups according to the formula —

O—

(CF2)4-SO2X, where X is F, Cl, Br, OH or O-M+, where M+ is a monovalent cation.

16. The method according to claim 3 wherein said pendent groups are groups according to the formula —

O—

(CF2)4-SO3H.

17. The method according to claim 4 wherein said pendent groups are according to the formula R1 SO2X, where R1 is a branched or unbranched perfluoroalkyl or perfluoroether group comprising 1-15 carbon atoms and 0-4 oxygen atoms, and where X is F, Cl, Br, OH or O-M+, where M+ is a monovalent cation.

18. The method according to claim 4 wherein said pendent groups are groups according to the formula —

O—

(CF2)4-SO2X, where X is F, Cl, Br, OH or O-M+, where M+ is a monovalent cation.

19. The method according to claim 4 wherein said pendent groups are groups according to the formula —

O—

(CF2)4-SO3H.

20. The method according to claim 1 wherein step c) comprises imbibing said fluoropolymer into a porous supporting matrix.

21. The method according to claim 20 wherein said porous supporting matrix is a porous polytetrafluoroethylene web.