Articles Including Expanded Polytetrafluoroethylene Membranes with Serpentine Fibrils and Having a Discontinuous Fluoropolymer Layer Thereon

• US 20130184807A1
• Filed: 11/13/2012
• Published: 07/18/2013
• Est. Priority Date: 01/16/2012
• Status: Active Grant

• Current Assignee: W. L. Gore & Associates (W.L. Gore & Associates)
• Original Assignee: W. L. Gore & Associates (W.L. Gore & Associates)
• Inventors: Kovach, Larry J., Radspinner, Rachel
• Granted Patent: US 9,510,935 B2
• Time in Patent Office: Days
• US Class Current: 623/1.13
• CPC Class Codes: A61F 2/07 Stent-grafts
• CPC Class Codes: A61F 2/82 Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents stent-grafts for tubular structures of the body other than blood vessels A61F2/04; stent-grafts for blood vessels A61F2/07; instruments specially adapted for placement or removal of stents or stent-grafts A61F2/95; for closing wounds, or holding wounds closed A61B17/04 - A61B17/115; dilators A61M29/00
• CPC Class Codes: A61F 2002/075 the stent being loosely attached to the graft material, e.g. by stitching
• CPC Class Codes: A61F 2240/002 Designing or making customized prostheses
• CPC Class Codes: A61L 31/048 obtained by reactions only involving carbon-to-carbon unsaturated bonds A61L31/041 takes precedence
• CPC Class Codes: A61L 31/10 Macromolecular materials
• CPC Class Codes: A61L 31/129 containing macromolecular fillers
• CPC Class Codes: A61L 31/146 Porous materials, e.g. foams or sponges
• CPC Class Codes: B29C 65/02 by heating, with or without pressure
• CPC Class Codes: B29C 66/545 one hollow-preform being placed inside the other
• CPC Class Codes: B29K 2055/00 Use of specific polymers obtained by polymerisation reactions only involving carbon-to-carbon unsaturated bonds, not provided for in a single one of main groups B29K2023/00 - B29K2049/00, e.g. having a vinyl group, as moulding material
• CPC Class Codes: B29K 2105/04 cellular or porous
• CPC Class Codes: B29K 2105/08 of continuous length, e.g. cords, rovings, mats, fabrics, strands or yarns
• CPC Class Codes: B29L 2009/00 Layered products
• CPC Class Codes: B29L 2031/753 Medical equipment; Accessories therefor bloodbags, medical bags B29L2031/7148; artificial eyes B29L2011/0008
• CPC Class Codes: B32B 1/08 Tubular products
• CPC Class Codes: B32B 2305/02 Cellular or porous
• CPC Class Codes: B32B 2355/00 Specific polymers obtained by polymerisation reactions only involving carbon-to-carbon unsaturated bonds, not provided for in a single one of index codes B32B2323/00 - B32B2333/00
• CPC Class Codes: B32B 2535/00 Medical equipment, e.g. bandage, prostheses or catheter
• CPC Class Codes: B32B 27/322 comprising halogenated polyolefins, e.g. PTFE
• CPC Class Codes: B32B 37/06 : characterised by the heating method
• CPC Class Codes: B32B 38/1866 : conforming the layers or laminate to a convex or concave profile
• CPC Class Codes: B32B 5/10 : characterised by a fibrous or filamentary layer reinforced with filaments
• CPC Class Codes: C08L 27/12 : containing fluorine atoms
• CPC Class Codes: C08L 27/18 : Homopolymers or copolymers or tetrafluoroethene
• CPC Class Codes: C09D 127/18 : Homopolymers or copolymers of tetrafluoroethene
• CPC Class Codes: F21V 33/0076 : Safety or security signalisation, e.g. smoke or burglar alarms, earthquake detectors; Self-defence devices
• CPC Class Codes: Y10T 156/1075 : of plural laminae from single stock and assembling to each other or to additional lamina
• CPC Class Codes: Y10T 428/24802 : Discontinuous or differential coating, impregnation or bond [e.g., artwork, printing, retouched photograph, etc.]
• CPC Class Codes: Y10T 428/2481 : including layer of mechanically interengaged strands, strand-portions or strand-like strips

Abstract

Articles comprising an expanded polytetrafluoroethylene membrane having serpentine fibrils and having a discontinuous coating of a fluoropolymer thereon are provided. The fluoropolymer may be located at least partially in the pores of the expanded fluoropolymer membrane. In exemplary embodiments, the fluoropolymer is fluorinated ethylene propylene. The application of a tensile force at least partially straightens the serpentine fibrils, thereby elongating the article. The expanded polytetrafluoroethylene membrane may include a microstructure of substantially only fibrils. The articles can be elongated to a predetermined point at which further elongation is inhibited by a dramatic increase in stiffness. In one embodiment, the articles are used to form a covered stent device that requires little force to distend in the radial direction to a first diameter but is highly resistant to further distension to a second diameter (stop point). A large increase in diameter can advantageously be achieved prior to reaching the stop point.

Claims

1. An article comprising an expanded fluoropolymer membrane having a discontinuous coating of a fluoropolymer thereon,

wherein said expanded fluoropolymer membrane includes serpentine fibrils, each said serpentine fibril having a width of about 1.0 micron or less.

2. The article of claim 1, wherein the expanded fluoropolymer membrane comprises pores and the fluoropolymer at least partially penetrates a plurality of said pores.

3. The article of claim 1, wherein the fluoropolymer is fluorinated ethylene propylene.

4. The article of claim 1, wherein the expanded fluoropolymer membrane is expanded polytetrafluoroethylene.

5. The article of claim 1, wherein the expanded fluoropolymer membrane comprises a microstructure of substantially only serpentine fibrils.

6. The article of claim 1, wherein the expanded fluoropolymer membrane comprises a plurality of serpentine fibrils.

7. The article of claim 1, wherein the expanded fluoropolymer membrane is thermally retracted in at least one direction to less than about 90% of the initial, expanded fluoropolymer membrane length.

8. The article of claim 7, wherein the expanded fluoropolymer membrane is thermally retracted in at least one direction.

9. The article of claim 8, wherein the expanded fluoropolymer membrane is restrained in at least one direction during said thermal retraction.

10. The article of claim 1, further comprising at least one elastomer incorporated at least partially into the expanded fluoropolymer membrane.

11. The article of claim 1, wherein said width of said serpentine fibril is 0.5 microns or less.

12. An endoprosthetic device comprising:

a wrinkle-free tubular member defining at least one opening, an interior surface, and an exterior surface, said tubular member comprising a composite material including an expanded fluoropolymer membrane having serpentine fibrils and a discontinuous coating of a fluoropolymer thereon.

13. The endoprosthetic device of claim 12, wherein each said serpentine fibril has a width of about 1.0 micron or less.

14. The endoprosthetic device of claim 13, wherein each said serpentine fibril has a width of 0.5 microns or less.

15. The endoprosthetic device of claim 12, wherein the expanded fluoropolymer membrane comprises pores and the fluoropolymer at least partially penetrates a plurality of said pores.

16. The endoprosthetic device of claim 12, wherein said expanded fluoropolymer membrane comprises expanded polytetrafluoroethylene.

17. The endoprosthetic device of claim 12, wherein said tubular member is a cover for a stent.

18. The endoprosthetic device of claim 17, wherein said fluoropolymer on said exterior surface bonds to said fluoropolymer on said interior surface through interstices of said stent to affix said cover to said stent.

19. The endoprosthetic device of claim 12, wherein said fluoropolymer comprises a member selected from the group consisting of fluorinated ethylene propylene (FEP), ethylene fluorinated ethylene propylene (EFEP), THV (a terpolymer of tetrafluoroethylene, hexafluoropropylene, and vinylidene fluoride), PFA (perfluoroalkoxy copolymer resin), ECTFE (ethylene chlorotrifluoroethylene), PVDF (polyvinylidene fluoride) and PEEK (polyether ether ketone).

20. The endoprosthetic device of claim 12, wherein said fluoropolymer is fluorinated ethylene propylene.

21. The endoprosthetic device of claim 12, wherein the expanded polytetrafluoroethylene membrane comprises a microstructure of substantially only serpentine fibrils.

22. The endoprosthetic device of claim 12, wherein the expanded fluoropolymer membrane comprises a plurality of serpentine fibrils.

23. The endoprosthetic device of claim 12, wherein said composite material is radially expanded to a diameter beyond which further expansion is inhibited.

24. The endoprosthetic device of claim 12, further comprising at least one elastomer incorporated at least partially into the expanded fluoropolymer membrane.

25. The endoprosthetic device of claim 12, wherein the expanded fluoropolymer membrane is thermally retracted in at least one direction to less than about 90% of the initial, expanded fluoropolymer membrane length.

26. The endoprosthetic device of claim 25, wherein the expanded fluoropolymer membrane is restrained in at least one direction during said thermal retraction.

27. The endoprosthetic device of claim 12, wherein said composite material exhibits an increase in stiffness when expanded to a diameter of about 7 mm.

28. A stent graft comprising:

a stent having a wall with at least one opening, an exterior surface, and an interior surface; and

a wrinkle-free cover affixed to said stent, said cover comprising a composite material including an expanded fluoropolymer membrane having serpentine fibrils and a discontinuous coating of a fluoropolymer thereon,

wherein said composite material at least partially covers at least one of the interior and exterior surfaces of said stent.

29. The stent graft of claim 28, wherein each said serpentine fibril has a width of about 1.0 micron or less.

30. The stent graft of claim 29, wherein each said serpentine fibril has a width of 0.5 microns or less.

31. The stent graft of claim 28, wherein the expanded fluoropolymer membrane comprises pores and the fluoropolymer at least partially penetrates a plurality of said pores.

32. The stent graft of claim 28, wherein said stent is extended to a first diameter at a first pressure and to a second diameter at a second pressure, said second pressure being greater than said first pressure.

33. The stent graft of claim 28, wherein said fluoropolymer on said exterior surface bonds to said fluoropolymer on said interior surface through interstices of said stent to affix said cover to said stent.

34. The stent graft of claim 28, wherein the fluoropolymer is fluorinated ethylene propylene.

35. The stent graft of claim 28, wherein the expanded fluoropolymer is expanded polytetrafluoroethylene.

36. The stent graft of claim 28, wherein the expanded fluoropolymer membrane comprises a microstructure of substantially only serpentine fibrils.

37. The stent graft of claim 28, wherein the expanded fluoropolymer membrane comprises a plurality of serpentine fibrils.

38. The stent graft of claim 28, wherein said composite material is radially expanded to a diameter beyond which further expansion is inhibited.

39. The stent graft of claim 28, wherein said composite material exhibits an increase in stiffness when expanded to a diameter of about 7 mm.

40. The stent graft of claim 28, wherein said composite material is free of wrinkles.

41. A method of forming a covered stent comprising:

positioning a first tubular member on an interior surface of a stent;

positioning a second tubular member on an external surface of said stent, each said tubular member comprising a composite material including an expanded polytetrafluoroethylene membrane having serpentine fibrils and a discontinuous coating of a fluoropolymer thereon, said fluoropolymer being positioned on an external surface of said first and tubular member and on an interior surface of said second tubular member; and

heating said stent having thereon said first and second tubular members to adhere said fluoropolymer on said first tubular member to said second tubular member through interstices of said stent and form a covered stent.

42. The method of claim 41, wherein the fluoropolymer is fluorinated ethylene propylene.

43. The method of claim 41, wherein the expanded fluoropolymer membrane comprises a microstructure of substantially only serpentine fibrils.

44. The method of claim 41, wherein the expanded fluoropolymer membrane comprises a plurality of serpentine fibrils.

45. The method of claim 41, wherein said composite material is radially expanded to a diameter beyond which further expansion is inhibited.

46. The method of claim 41, wherein said first and second tubular members are wrinkle-free.

47. The method of claim 41, wherein the expanded fluoropolymer membrane comprises pores and the fluoropolymer at least partially penetrates a plurality of said pores.

48. The method of claim 41, wherein said composite material exhibits an increase in stiffness when expanded to a diameter of about 7 mm.

49. The method of claim 41, wherein each said serpentine fibril has a width of about 1.0 micron or less.

51. A method of forming a covered stent comprising:

forming a tube comprising a composite material including an expanded polytetrafluoroethylene membrane and a discontinuous coating of a fluoropolymer thereon, said fluoropolymer being positioned on an external surface of said tube;

cutting said tube cross-sectionally to form a first tubular member and a second tubular member;

everting said second tubular member to position said fluoropolymer on an interior surface of said second tubular member;

positioning said first tubular member within a stent;

positioning said second tubular member on an external surface of said stent; and

heating said covered stent to adhere said fluoropolymer on said first tubular member to said second tubular member through interstices of said stent to form a covered stent.

50. The method of claim 51, wherein each said serpentine fibril has a width of 0.5 microns or less.

52. The method or claim 51, wherein said expanded fluoropolymer membrane comprises a microstructure of serpentine fibrils.

53. The method of claim 52, wherein each said serpentine fibril has a width of about 1.0 micron or less.