Graft polymeric membranes and ion-exchange membranes formed therefrom

• US 6,723,758 B2
• Filed: 08/21/2001
• Issued: 04/20/2004
• Est. Priority Date: 11/12/1997
• Status: Expired due to Fees

• Current Assignee: BDF IP Holdings Ltd. (Siemens AG)
• Original Assignee: Ballard Power Systems Corporation (Siemens AG)
• Inventors: Choudhury, Biswajit, Stone, Charles, Steck, Alfred E.
• Primary Examiner(s): Lipman, Bernard
• Application Number:
  US09/934,176
• Publication Number:
  US 20020137806A1
• Time in Patent Office: 973 Days
• Field of Search: 521/27, 521/32, 521/33, 525/359.1, 525/416
• US Class Current: 521/27
• CPC Class Codes: B01D 2323/38 Graft polymerization
• CPC Class Codes: B01D 67/0006 by chemical reactions in-situ polymerisation, polycondensation, cross-linking or reaction for manufacturing composite membranes B01D69/125
• CPC Class Codes: B01D 67/00931 by introduction of specific groups after membrane formation, e.g. by grafting
• CPC Class Codes: B01D 71/281 Polystyrene
• CPC Class Codes: B01D 71/32 containing fluorine atoms
• CPC Class Codes: B01D 71/36 Polytetrafluoroethene
• CPC Class Codes: B01D 71/82 characterised by the presence of specified groups, e.g. introduced by chemical after-treatment
• CPC Class Codes: C08F 255/02 on to polymers of olefins having two or three carbon atoms
• CPC Class Codes: C08F 255/023 On to modified polymers, e.g. chlorinated polymers
• CPC Class Codes: C08F 259/08 on to polymers containing fluorine
• CPC Class Codes: C08F 291/00 Macromolecular compounds obtained by polymerising monomers on to macromolecular compounds according to more than one of the groups C08F251/00 - C08F289/00
• CPC Class Codes: C08F 291/18 on to irradiated or oxidised macromolecules epoxidised C08F291/10
• CPC Class Codes: C08J 2327/12 containing fluorine atoms
• CPC Class Codes: C08J 5/225 containing fluorine
• CPC Class Codes: C08J 7/16 with polymerisable compounds
• 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

Graft polymeric membranes and methods for making graft polymeric membranes have one or more trifluorovinyl aromatic monomers that are radiation graft polymerized to a polymeric base film. The membranes comprise a polymeric base film to which has been graft polymerized substituted α,α,β-trifluorostyrene and/or α,α,β-trifluorovinylnaphthylene monomers, which are activated towards graft polymerization. As ion-exchange membranes, the membranes are suitable for use in electrode apparatus, including membrane electrode assemblies in, for example, fuel cells. The membranes can also be crosslinked.

Claims

1. A membrane comprising a polymeric base film with grafted chains comprising monomer units of formula (IV)

wherein A₁ is para-methyl and A₂ is hydrogen;

and wherein at least a portion of said monomer units further comprise at least one ion-exchange substituent, thereby rendering said membrane an ion-exchange membrane.

2. The membrane of claim 1 wherein at least a portion of the grafted chains is crosslinked.

3. The membrane of claim 1 wherein said at least one ion-exchange substituent is selected from the group consisting of sulfonate and sulfonic acid.

4. The membrane of claim 1 wherein at least a portion of said monomer units comprise at least two ion-exchange substituents.

5. The membrane of claim 1 wherein at least 50% of said monomer units in said grafted chains have at least one ion-exchange substituent per monomer unit.

6. The membrane of claim 1 wherein said grafted chains comprise at least two different types of ion-exchange groups.

7. The membrane of claim 1 wherein said grafted chains comprise an anion-exchange group and a cation-exchange group.

8. The membrane of claim 1 wherein said membrane is substantially gas impermeable.

9. The membrane of claim 3 wherein said membrane is substantially gas impermeable.

10. The membrane of claim 1 wherein said base film comprises poly(ethylene-co-tetrafluoro-ethylene), and said at least one ion-exchange substituent is selected from the group consisting of a sulfonate group and a sulfonic acid group.