Surface modified porous expanded polytetrafluoroethylene and process for making

• US 5,437,900 A
• Filed: 12/01/1993
• Issued: 08/01/1995
• Est. Priority Date: 06/14/1991
• Status: Expired due to Term

• Current Assignee: W. L. Gore & Associates (W.L. Gore & Associates)
• Original Assignee: W. L. Gore & Associates (W.L. Gore & Associates)
• Inventors: Kuzowski, Stanislaw L.
• Primary Examiner(s): CANNON, JAMES
• Application Number:
  US08/161,184
• Time in Patent Office: 608 Days
• Field of Search: 43/44.98, 55/522, 55/528, 55/529, 55/DIG. 5, 128/DIG. 14, 156/643, 174/110 FC, 204/157.61, 210/500.24, 210/508, 210/510.1, 427/534, 427/569, 428/36.1, 428/36.4, 428/36.9, 428/36.92, 428/224, 428/308.4, 428/311.5, 428/376, 428/398, 428/409, 428/422, 600/36, 606/231, 623/1, 623/8, 623/11, 623/12, 623/66, 623/901
• US Class Current: 428/36.1
• CPC Class Codes: A01K 91/12 Fly lines
• CPC Class Codes: A61F 2/06 Blood vessels
• CPC Class Codes: A61L 2400/18 Modification of implant surfaces in order to improve biocompatibility, cell growth, fixation of biomolecules, e.g. plasma treatment
• CPC Class Codes: A61L 27/16 obtained by reactions only involving carbon-to-carbon unsaturated bonds
• CPC Class Codes: B01D 39/1692 Other shaped material, e.g. perforated or porous sheets
• CPC Class Codes: B29C 59/14 by plasma treatment plasma tubes per se H01J
• CPC Class Codes: B29K 2027/18 PTFE, i.e. polytetrafluorethene , e.g. ePTFE, i.e. expanded polytetrafluorethene
• CPC Class Codes: B29K 2105/04 cellular or porous
• CPC Class Codes: C08J 2327/18 Homopolymers or copolymers of tetrafluoroethylene
• CPC Class Codes: C08J 5/18 Manufacture of films or sheets
• CPC Class Codes: C08L 27/18 Homopolymers or copolymers or tetrafluoroethene
• CPC Class Codes: F23G 2202/20 to temperatures melting waste
• CPC Class Codes: F23L 2900/07005 Injecting pure oxygen or oxygen enriched air
• CPC Class Codes: Y02E 20/34 Indirect CO2mitigation, i.e. by acting on non CO2directly related matters of the process, e.g. pre-heating or heat recovery
• CPC Class Codes: Y10S 128/14 Polytetrafluoroethylene, i.e. PTFE
• CPC Class Codes: Y10S 55/05 Methods of making filter
• CPC Class Codes: Y10S 623/901 Method of manufacturing prosthetic device
• CPC Class Codes: Y10T 428/1362 Textile, fabric, cloth, or pile containing [e.g., web, net, woven, knitted, mesh, nonwoven, matted, etc.]
• CPC Class Codes: Y10T 428/1372 Randomly noninterengaged or randomly contacting fibers, filaments, particles, or flakes
• CPC Class Codes: Y10T 428/139 Open-ended, self-supporting conduit, cylinder, or tube-type article
• CPC Class Codes: Y10T 428/1397 : Single layer [continuous layer]
• CPC Class Codes: Y10T 428/249958 : Void-containing component is synthetic resin or natural rubbers
• CPC Class Codes: Y10T 428/249964 : Fibers of defined composition
• CPC Class Codes: Y10T 428/2935 : Discontinuous or tubular or cellular core
• CPC Class Codes: Y10T 428/2975 : Tubular or cellular
• CPC Class Codes: Y10T 428/31 : Surface property or characteristic of web, sheet or block
• CPC Class Codes: Y10T 428/31544 : Addition polymer is perhalogenated
• CPC Class Codes: Y10T 442/60 : Nonwoven fabric [i.e., nonwoven strand or fiber material]

Abstract

Porous expanded polytetrafluoroethylene material having a microstructure of nodes interconnected by fibrils wherein a surface of the material has been modified to have increased hydrophobicity as indicated by having a water droplet roll-off angle of less than about 10 degrees in comparison to a typical roll-off angle of greater than about 12 degrees for the unmodified material. Under magnification, the surface morphology may be indistinguishable from that of the unmodified precursor material. The modification is preferably done by exposing the surface to radio frequency gas plasma discharge with a reactive etching gas for a lengthy amount of time such as about ten minutes. If surface etching is continued beyond a time adequate to produce the highly hydrophobic behavior, then the surface morphology includes the appearance of broken fibrils. Still further treatment results in complete removal of fibrils from the surface so that under magnification the surface has the appearance of freestanding node portions not interconnected by fibrils but rather having open valleys disposed between the freestanding node portions.

Claims

1. Porous expanded polytetrafluoroethylene having a microstructure comprised of nodes interconnected by fibrils, said porous expanded polytetrafluoroethylene comprising a three dimensional material having at least one surface wherein at least a substantial portion of the at least one surface is comprised of freestanding node portions with open valleys disposed between the freestanding node portions.

2. Porous expanded polytetrafluoroethylene according to claim 1 wherein the porous expanded polytetrafluoroethylene has a water droplet roll-off angle of less than about 10 degrees.

3. Porous expanded polytetrafluoroethylene according to claim 1 wherein the porous expanded polytetrafluoroethylene has a water droplet roll-off angle of less than about 8 degrees.

4. Porous expanded polytetrafluoroethylene according to claim 1 wherein the porous expanded polytetrafluoroethylene has a water droplet roll-off angle of less than about 6 degrees.

5. Porous expanded polytetrafluoroethylene according to claim 1 wherein the porous expanded polytetrafluoroethylene has a water droplet roll-off angle of less than about 4 degrees.

6. Porous expanded polytetrafluoroethylene according to claim 1 wherein the three dimensional material is in the form of a tubular shape having an inner surface and an outer surface and the at least one surface comprises the inner surface of the tubular shape.

7. Porous expanded polytetrafluoroethylene according to claim 6 wherein the tubular shape is a vascular graft.

8. Porous expanded polytetrafluoroethylene according to claim 6 wherein the tubular shape is a filter.

9. Porous expanded polytetrafluoroethylene according to claim 6 wherein the tubular shape is a wire insulation.

10. Porous expanded polytetrafluoroethylene according to claim 1 wherein the three dimensional material is in the form of a tubular shape having an inner surface and an outer surface and the at least one surface comprises the outer surface of the tubular shape.

11. Porous expanded polytetrafluoroethylene according to claim 10 wherein the tubular shape is a vascular graft.

12. Porous expanded polytetrafluoroethylene according to claim 10 wherein the tubular shape is a filter.

13. Porous expanded polytetrafluoroethylene according to claim 10 wherein the tubular shape is a wire insulation.

14. Porous expanded polytetrafluoroethylene according to claim 10 wherein the tubular shape is a fly line outer surface.

15. Porous expanded polytetrafluoroethylene according to claim 1 wherein the three dimensional material is in the form of a flat sheet.

16. Porous expanded polytetrafluoroethylene according to claim 15 wherein the flat sheet is a filter.

17. Porous expanded polytetrafluoroethylene according to claim 15 wherein the flat sheet is a layer of a garment material.

18. Porous expanded polytetrafluoroethylene according to claim 15 wherein the flat sheet is an implantable patch.

19. Porous expanded polytetrafluoroethylene according to claim 15 wherein the flat sheet is an implantable membrane.

20. Porous expanded polytetrafluoroethylene according to claim 11 wherein the three dimensional material is in the form of a cylindrical shape having a curved outer surface and the at least one surface comprises the curved outer surface.

21. Porous expanded polytetrafluoroethylene according to claim 20 wherein the cylindrical shape is a suture.

22. A method of modifying a surface of a porous expanded polytetrafluoroethylene material said porous expanded polytetrafluoroethylene material having a microstructure of nodes interconnected by fibrils, said method comprising exposing the surface to a reactive gas plasma discharge until the fibrils are removed from at least a substantial portion of the surface and the surface is comprised of freestanding node portions with open valleys disposed between the freestanding node portions.