Magnetic composites exhibiting distinct flux properties due to gradient interfaces

• US 6,514,575 B2
• Filed: 06/08/2001
• Issued: 02/04/2003
• Est. Priority Date: 08/25/1994
• Status: Expired due to Fees

• Current Assignee: University of Iowa Research Foundation
• Original Assignee: University of Iowa Research Foundation
• Inventors: Leddy, Johna, Amarasinghe, Sudath
• Primary Examiner(s): PIANALTO, BERNARD D
• Application Number:
  US09/876,035
• Publication Number:
  US 20020004106A1
• Time in Patent Office: 606 Days
• Field of Search: 427/547, 427/58, 427/558, 427/123, 427/598, 427/126.6, 427/128, 427/127, 427/130, 427/129, 427/190, 427/132, 427/191, 427/195, 427/215, 427/216, 427/221, 427/222, 427/385.5, 427/388.1, 427/393.5, 427/430.1, 427/443.2
• US Class Current: 427/550
• CPC Class Codes: B01D 39/04 Organic material, e.g. cellulose, cotton
• CPC Class Codes: B01D 39/06 Inorganic material, e.g. asbestos fibres, glass beads or fibres
• CPC Class Codes: B03C 1/01 by addition of magnetic adjuvants
• CPC Class Codes: B03C 1/02 acting directly on the substance being separated
• CPC Class Codes: B82Y 25/00 Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
• CPC Class Codes: C23C 30/00 Coating with metallic material characterised only by the composition of the metallic material, i.e. not characterised by the coating process C23C26/00, C23C28/00 take precedence
• CPC Class Codes: C25B 11/00 Electrodes; Manufacture thereof not otherwise provided for
• CPC Class Codes: H01M 4/86 Inert electrodes with catalytic activity, e.g. for fuel cells
• CPC Class Codes: H01M 4/8605 Porous electrodes
• CPC Class Codes: H01M 8/00 Fuel cells; Manufacture thereof
• CPC Class Codes: H01M 8/1004 characterised by membrane-electrode assemblies [MEA] H01M8/12 takes precedence
• CPC Class Codes: Y02E 60/50 Fuel cells
• CPC Class Codes: Y10S 204/05 Magnetic plus electrolytic
• CPC Class Codes: Y10S 428/90 Magnetic feature
• CPC Class Codes: Y10T 428/32 Composite [nonstructural laminate] of inorganic material having metal-compound-containing layer and having defined magnetic layer

Abstract

Magnetic composites exhibit distinct flux properties due to gradient interfaces. The composites can be used to improve fuel cells and effect transport and separation of different species of materials. A variety of devices can be made utilizing the composites including a separator, a cell, an electrode for channeling flux of magnetic species, an electrode for effecting electrolysis of magnetic species, a system for channeling electrolyte species, a system for separating particles with different magnetic susceptibilities. Some composites can be used to make a dual sensor for distinguishing between two species of materials and a flux switch to regulate the flow of a redox species and a flux switch to regulate the flow of a chemical species. Some composites can control chemical species transport and distribution.

Claims

1. A method of making an electrode with a surface coated with a magnetic composite with a plurality of boundary regions with magnetic gradients having paths to the surface of said electrode, comprising the steps of:

mixing a first solution which includes a suspension of at least approximately 1 percent by weight of inert polymer coated magnetic microbeads containing between approximately 10 percent and approximately 90 percent magnetizable polymer material having diameters at least 0.5 micrometers in a first solvent with a second solution of at least approximately 2 percent by weight of ion exchange polymers in a second solvent to yield a mixed suspension;

applying said mixed suspension to the surface of the electrode, said electrode being arranged in a magnetic field of at least approximately 0.05 Tesla which has a component oriented approximately along the normal of said electrode surface; and

evaporating said first solvent and said second solvent to yield the electrode with a surface coated with the magnetic composite having a plurality of boundary regions with magnetic gradients having paths to the surface of the electrode.

2. The method as claimed in claim 1, wherein said mixing step comprises mixing said first solution which includes a suspension of between approximately 2 percent and approximately 10 percent by weight of inert polymer coated magnetic microbeads with said second solution.

3. The method as claimed in claim 1, wherein said mixing step comprises mixing said first solution which includes inert polymer coated magnetic microbeads containing between 50 percent and 90 percent magnetizable polymer material with said second solution.

4. The method as claimed in claim 1, wherein said mixing step comprises mixing said first solution which includes inert polymer coated magnetic microbeads containing 90 percent magnetizable polymer material with said second solution.

5. The method as claimed in claim 1, wherein said applying step comprises applying approximately between 2 percent and approximately 75 percent by volume of said mixed suspension to the surface of the electrode.

6. The method as claimed in claim 1, wherein said applying step comprises applying between 25 percent and 60 percent by volume of said mixed suspension to the surface of the electrode.

7. The method as claimed in claim 1, wherein said mixing step comprises mixing a first solution which includes a suspension of at least approximately 5 percent by weight of inert polymer coated magnetic microbeads containing between approximately 10 percent and approximately 90 percent magnetizable polymer material having diameters ranging between approximately 0.5 micrometers and approximately 12 micrometers.

8. The method as claimed in claim 1, wherein said mixing step comprises mixing a first solution which includes a suspension of at least approximately 5 percent by weight of inert polymer coated magnetic microbeads containing between approximately 10 percent and approximately 90 percent magnetizable polymer material having diameters ranging between approximately 1 micrometer and approximately 2 micrometers.

9. The method as claimed in claim 1, wherein said applying step comprises applying said mixed suspension to the surface of the electrode, said electrode being arranged in a magnetic field between approximately 0.05 Tesla and approximately 2 Tesla.

10. The method as claimed in claim 1, wherein said applying step comprises applying said mixed suspension to the surface of the electrode, said electrode being arranged in a magnetic field of approximately 2 Tesla.

11. The method as claimed in claim 1, wherein said mixing step comprises mixing a first solution which includes a suspension of at least approximately 5 percent by weight of inert polymer coated magnetic microbeads containing between approximately 10 percent and approximately 90 percent magnetizable polymer material having diameters at least 0.5 micrometers in a first solvent with a second solution of at least approximately 5 percent by weight of Nafion in a second solvent to yield said mixed suspension.

12. The method as claimed in claim 1, wherein said mixing step comprises mixing a first solution which includes a suspension of at least approximately 5 percent by weight of inert polymer coated magnetic microbeads containing between approximately 10 percent and approximately 90 percent organo-Fe material having diameters at least 0.5 micrometers in a first solvent with a second solution of at least approximately 5 percent by weight of ion exchange polymers in a second solvent to yield said mixed suspension.

13. A method of making an electrode with a surface coated with a composite with a plurality of boundary regions with magnetic gradients having paths to the surface of said electrode when an external magnetic field is turned on, comprising the steps of:

mixing a first solution which includes a suspension of at least 5 percent by weight of inert polymer coated microbeads containing between 10 percent and 90 percent magnetizable non-permanent magnet material having diameters at least 0.5 micrometers in a first solvent with a second solution of at least 5 percent of ion exchange polymers in a second solvent to yield a mixed suspension;

applying said mixed suspension to the surface of the electrode;

evaporating said first solvent and said second solvent to yield the electrode with a surface coated with the composite having a plurality of boundary regions with magnetic gradients having paths to the surface of the electrode when the external magnet is turned on.

14. The method as claimed in claim 13, wherein said magnetizable non-permanent magnet material comprises Fe/Fe oxide material.