FILTRATION MEMBRANES WITH FUNCTIONALIZED STAR POLYMERS

• US 20160008769A1
• Filed: 07/14/2014
• Published: 01/14/2016
• Est. Priority Date: 07/14/2014
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Dubois, Geraud J., Lee, Victor Y., Miller, Robert D., Na, Young-Hye, Sly, Joseph
• Granted Patent: US 9,782,727 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B01D 2323/02 Hydrophilization
• CPC Class Codes: B01D 2323/30 Cross-linking
• CPC Class Codes: B01D 2323/345 UV-treatment
• CPC Class Codes: B01D 2323/36 Introduction of specific chemical groups
• CPC Class Codes: B01D 2325/04 Characteristic thickness
• CPC Class Codes: B01D 2325/14 Membrane materials having negatively charged functional groups
• CPC Class Codes: B01D 2325/16 Membrane materials having positively charged functional groups
• CPC Class Codes: B01D 2325/18 Membrane materials having mixed charged functional groups
• CPC Class Codes: B01D 2325/26 Electrical properties
• CPC Class Codes: B01D 2325/36 Hydrophilic membranes
• CPC Class Codes: B01D 61/027 Nanofiltration
• 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 69/02 characterised by their properties
• CPC Class Codes: B01D 69/12 Composite membranes; Ultra-thin membranes
• CPC Class Codes: B01D 69/1214 Chemically bonded layers, e.g. cross-linking
• CPC Class Codes: B01D 69/125 In situ manufacturing by polymerisation, polycondensation, cross-linking or chemical reaction
• CPC Class Codes: B01D 69/1251 by interfacial polymerisation
• CPC Class Codes: B01D 71/5211 Polyethylene glycol or polyethyleneoxide
• CPC Class Codes: B01D 71/80 Block polymers
• CPC Class Codes: B01D 71/82 characterised by the presence of specified groups, e.g. introduced by chemical after-treatment
• CPC Class Codes: C08F 2438/01 : Atom Transfer Radical Polymerization [ATRP] or reverse ATRP
• CPC Class Codes: C08F 293/005 : using free radical "living" or "controlled" polymerisation, e.g. using a complexing agent

Abstract

A thin film composite membrane (TFC) includes an active layer on a support. The active layer includes at least 8 barrier layers of star-polymers each having at least three linear polymers attached at a central core. Each of the barrier layers has a thickness between 5 and 50 nm, and the barrier layers have alternating charge.

Claims

1. A thin film composite membrane (TFC) comprising an active layer on a support, wherein the active layer comprises at least 8 barrier layers of star-polymers, wherein the star-polymers comprise at least three linear polymers attached at a central core, and wherein each of the barrier layers a thickness between 5 and 50 nm, the barrier layers having alternating charge.

2. The membrane of claim 1, wherein the barrier layers adhere to one another with electrostatic interaction.

3. The membrane of claim 1, wherein at least one of the barrier layers of alternating layers of star polymers adhere to one another with hydrogen-bonding.

4. The membrane of claim 2, wherein at least one of the barrier layers comprises a negatively charged star-polymer with a carboxyl moiety.

5. The membrane of claim 2, wherein at least one of the barrier layers comprises a positively charged star-polymer with an ammonium moiety.

6. The membrane of claim 2, wherein at least one of the barrier layers comprises an electrically neutral hydrophilic surface functional moiety.

7. The membrane of claim 6, wherein the neutral hydrophilic surface functional moiety is polyethylene glycol.

8. A method for making a membrane, comprising:

a) exposing a surface of a support membrane having a first surface potential to a first solution to form a first charged barrier layer on the surface, wherein the first solution comprises a first star polymer in a first solvent, and wherein the first star polymer has a second surface potential opposite the first surface potential;

b) exposing the first charged barrier layer to a second solution to form a second charged barrier layer on the first charged barrier layer, wherein the second solution comprises a second solvent and a second star polymer having a third surface potential opposite the second surface potential; and

c) repeating steps a) and b) to form a multilayer stack of barrier layers on the support membrane, wherein each of the barrier layers comprises self-assembled star polymers.

9. The method of claim 8, wherein the barrier layers are applied by dip coating, spinning or spray coating, and combinations thereof.

10. The method of claim 8, comprising rinsing the surface of the first charged barrier layer with a solvent prior to step b).

11. The method of claim 8, comprising rinsing the surface of the second charged barrier layer with a solvent prior to step c).

12. The method of claim 8, wherein the first solvent is water.

13. The method of claim 8, wherein the second solvent is water.

14. The method of claim 8, wherein the support membrane has an average pore diameter in the range of about 1 to about 50 nm.

15. The method of claim 8, wherein the support membrane has an average pore diameter in the range of about 5 to about 20 nm.

16. The method of claim 8, wherein the first star polymer comprises ammonium functionality.

17. The method of claim 8, wherein the second star polymer comprises carboxyl functionality.

18. The method of claim 8, wherein the surface of the support membrane is pre-treated by application of at least one of a plasma, ultraviolet light and ozone prior to step (a).

19. The method of claim 8, comprising crosslinking the multilayer stack following step c) by at least one of thermal treatment, photochemical treatment, and by using a cross-linking agent.

20. The method of claim 8, wherein the active layer comprises at least 8 barrier layers of star-polymers, and wherein each of the barrier layers has a thickness between 5 and 50 nm, the barrier layers having an alternating charge.