Porous membranes

• US 6,395,325 B1
• Filed: 05/16/2000
• Issued: 05/28/2002
• Est. Priority Date: 05/16/2000
• Status: Expired due to Fees

• Current Assignee: Scimed Life Systems Incorporated (Boston Scientific Corporation)
• Original Assignee: Scimed Life Systems Incorporated (Boston Scientific Corporation)
• Inventors: Hedge, Anant V., Swanson, David K.
• Primary Examiner(s): Parker, Fred J.
• Assistant Examiner(s): Michener, Jennifer Kolb
• Application Number:
  US09/573,071
• Time in Patent Office: 742 Days
• Field of Search: 427/407.1,2.24,2.11,2.3,2.31,243,244,245,282
• US Class Current: 427/2.11
• CPC Class Codes: A61L 29/085 Macromolecular materials
• CPC Class Codes: A61L 29/146 Porous materials, e.g. foams or sponges
• CPC Class Codes: B01D 2323/12 Specific ratios of components used
• CPC Class Codes: B01D 2325/36 Hydrophilic membranes
• CPC Class Codes: B01D 67/0002 Organic membrane manufacture
• CPC Class Codes: B01D 67/0013 Casting processes
• CPC Class Codes: B01D 67/0088 Physical treatment with compounds, e.g. swelling, coating or impregnation
• CPC Class Codes: B01D 69/02 characterised by their properties
• CPC Class Codes: B01D 71/34 Polyvinylidene fluoride
• CPC Class Codes: B01D 71/441 Polyvinylpyrrolidone
• CPC Class Codes: B29C 41/02 for making articles of definite length, i.e. discrete articles
• CPC Class Codes: B29C 41/14 Dipping a core B29C41/10 takes precedence
• CPC Class Codes: B29C 41/22 Making multilayered or multicoloured articles
• CPC Class Codes: B29K 2995/0092 hydrophilic
• CPC Class Codes: B29K 2995/0093 hydrophobic
• CPC Class Codes: B29L 2031/753 Medical equipment; Accessories therefor bloodbags, medical bags B29L2031/7148; artificial eyes B29L2011/0008
• CPC Class Codes: C08L 27/16 Homopolymers or copolymers or vinylidene fluoride
• CPC Class Codes: C08L 39/06 Homopolymers or copolymers of N-vinyl-pyrrolidones

Abstract

This invention relates to a novel method for the formation of porous hydrophilic membranes, to the membranes themselves, and to uses for them.

Claims

1. A method for forming a porous membrane, comprising:

dissolving one or more polymers in one or more solvents at a temperature at which a true solution of the polymer or polymers forms;

applying the solution to a surface; and

,

drying the applied solution at a temperature that is above the flash point of the solvent or each of the solvents and below the softening point of the polymer or each of the polymers until the solvent or solvents have been substantially completely removed.

2. The method of claim 1 using one polymer.

3. The method of claim 2, wherein the polymer used is a hydrophobic polymer.

4. The method of claim 2, wherein the polymer used is a hydrophilic polymer.

5. The method of claim 1, using a plurality of polymers.

6. The method of claim 5, wherein one or more of the plurality of polymers used is hydrophobic and one or more of the plurality of polymers used is hydrophilic.

7. The method of claim 6, wherein the porous membrane formed is a hydrophilic porous membrane.

8. The method of claim 5, wherein the hydrophobic polymer or polymers are dissolved in the solvent or solvents before the hydrophilic polymer or polymers are added to the solvent or solvents.

9. The method of claim 6, wherein the hydrophobic polymer or polymers each has a softening point above 100°

C.

10. The method of claim 9, wherein the hydrophilic polymer or polymers each has a softening point above 100°

C.

11. The method of claim 5, wherein two polymers, one hydrophobic and the other hydrophilic, are used.

12. The method of claim 10, wherein:

the hydrophobic polymer used is poly(vinylidene fluoride); and

,

the hydrophilic polymer used is poly(N-vinylpyrrolidone).

13. The method of claim 12, wherein the weight/weight ratio of poly(vinylidene fluoride) used to poly(N-vinylpyrrolidone) used is from about 1:

0.5 to about 1;

2.

14. The method of claim 12, wherein the weight/weight ratio of poly(vinylidene fluoride) used to poly(N-vinylpyrrolidone) used is about 1:

1.

15. The method of claim 12, wherein the solvent comprises N,N-dimethylacetamide.

16. The method of claim 15, wherein the solvent further comprises an acid.

17. The method of claim 16, wherein the acid is an organic acid.

18. The method of claim 17, wherein the acid is glacial acetic acid.

19. The method of claim 15, wherein the temperature at which the poly(vinylidene fluoride) is dissolved in N,N-dimethylacetamide is from about 30°

C. to about 50°

C.

20. The method of claim 15, wherein the temperature at which the poly(vinylidene fluoride) is dissolved in the N,N-dimethylacetamide is from about 35°

C. to about 40°

C.

21. The method of claim 15, wherein the temperature at which the poly(N-vinylpyrrolidone) is dissolved in the N,N-dimethylacetamide is about 18°

to about 30°

C.

22. The method of claim 12, wherein the temperature which is above the flash point of the solvent is from about 88°

C. to about 92°

C.

23. The method of any one of claims 1, 5, 11 or 12, wherein the surface to which the solution of the polymer or polymers is applied is a mold.

24. The method of claim 23, wherein the mold is a balloon mold.

25. The method of any one of claims 1, 5, 11 or 12, wherein the surface to which the solution of the polymer or polymers is applied is a medical device.

26. The method of claim 25, wherein the medical device comprises a diagnostic device.

27. The method of claim 25, wherein the medical device comprises a therapeutic device.

28. The method of claim 27, wherein the therapeutic device is an ablation catheter.

29. The method of claim 25, wherein the medical device comprises a drug delivery device.

30. The method of claim 29, wherein the drug delivery device comprises an electrophoretic drug delivery device.

31. A hydrophobic porous membrane made using the method of any one of claims 1, 3 or 5.

32. A hydrophilic porous membrane made using the method of any one of claims 1, 4, 6 or 11.

33. A hydrophilic porous membrane made using the method of any one of claims 12, 13 or 14.

34. A biocompatible hydrophilic porous membrane made using the method of any one of claims 1, 4, 6, 11, 12, 13 or 14.

35. The method of claim 1, wherein the porous membrane formed has a thickness of from about 0.05 to about 50 mils.

36. The method of claim 1, wherein the porous membrane formed has a thickness of from about 1 to about 5 mils.

37. A method for forming a selectively porous membrane, comprising:

dissolving one or more first polymers in one or more first solvents at a temperature at which a true solution of the first polymer or polymers forms to obtain a first solution;

applying the first solution to a surface;

drying the applied solution at a temperature that is above the flash point of the solvent or each of the solvents and below the softening point of the polymer or each of the polymers until the solvent or solvents have been substantially completely removed to form a porous membrane;

masking the porous membrane to protect those areas in which porosity is to be maintained;

dissolving one or more second polymers in one or more second solvents at a temperature at which a true solution of the second polymer or polymers forms to give a second solution;

applying the second solution to the masked membrane;

drying the applied second solution at a temperature that is below the flash point of the second solvent or each of the solvents and below the softening point of the second polymer or each of the polymers until the second solvent or solvent have been substantially completely removed to form a non-porous membrane over those portions of the porous membrane where porosity is not to be maintained; and

,

removing the mask.

38. The method of claim 37, wherein the first and second solutions are the same.

39. The method of claim 38, wherein the first and second membranes formed are both hydrophilic.

40. The method of claim 37, wherein the first and second solutions are different.

41. The method of claim 40, wherein drying the first solution results in formation of a porous, hydrophilic membrane and drying the second solution results in formation of a non-porous, hydrophobic membrane.

42. The method of claim 40, wherein drying the first solution results in formation of a porous, hydrophobic membrane and drying the second solution results in formation of a non-porous, hydrophilic membrane.