Fluorinated silica microchannel surfaces

• US 20040052929A1
• Filed: 09/16/2002
• Published: 03/18/2004
• Est. Priority Date: 09/16/2002
• Status: Active Grant

• Current Assignee: National Technology & Engineering Solutions Of Sandia LLC (Honeywell International Inc.)
• Original Assignee: Sandia National Laboratories (Government of the United States of America)
• Inventors: Kirby, Brian J., Shepodd, Timothy Jon
• Granted Patent: US 6,865,939 B2
• Time in Patent Office: Days
• US Class Current: 427/58
• CPC Class Codes: B05D 2203/30 Other inorganic substrates, e.g. ceramics, silicon
• CPC Class Codes: B05D 2254/04 Applying the material on the interior of the tube
• CPC Class Codes: B05D 3/0254 After-treatment
• CPC Class Codes: B05D 5/083 involving the use of fluoropolymers

Abstract

A method for surface modification of microchannels and capillaries. The method produces a chemically inert surface having a lowered surface free energy and improved frictional properties by attaching a fluorinated alkane group to the surface. The coating is produced by hydrolysis of a silane agent that is functionalized with either alkoxy or chloro ligands and an uncharged C₃-C₁₀ fluorinated alkane chain. It has been found that the extent of surface coverage can be controlled by controlling the contact time from a minimum of about 2 minutes to a maximum of 120 minutes for complete surface coverage.

Claims

1. A method of coating the interior surface of a microchannel with a fluorocarbon coating, comprising:

contacting the microchannel walls with a chemical mixture comprising an acid catalyst and a functionalized silane agent in a solvent, wherein the chemical mixture is contacted with the microchannel walls for a predetermined period of time and at a fixed temperature to control the extent to which the walls are coated.

2. The method of claim 1, wherein the silane agent is functionalized with an uncharged fluorinated alkane and alkoxy or halogen ligands.

3. The method of claim 2, wherein the halogen ligands are chloro ligands.

4. The method of claim 2, wherein the uncharged fluorinated alkane is an uncharged C₃-C₁₀ fluorinated alkane chain.

5. The method of claim 2, wherein alkoxy is methoxy, ethoxy, acetoxy, methoxyethoxy or methoxymethyl.

6. The method of claim 1, wherein the silane agent is (tridecafluoro-1,1,2,2-tetrahydrooctyl)triethoxysilane.

7. The method of claim 1, wherein the period of time is in the range of from about 2 to about 120 minutes.

8. The method of claim 1, wherein the fixed temperature is a temperature in the range of from about 50 to 90°

C.

9. The method of claim 8, wherein the temperature is about 70°

C.

10. The method of claim 1, wherein the microchannel is a silica microchannel.

11. A device comprising a system of microchannels, wherein the interior surfaces of the microchannels are coated with the fluorocarbon coating of claim 1.

12. An improved device for controlling fluid flow in a microchannel in which a mobile, monolithic polymer element, made by polymerizing a monomer mixture within the microchannel, is disposed in the microchannel, and in which a displacing force controls the movement of the monolithic polymer element in the microchannel, w herein the improvement comprises coating the interior surface of the microchannel with the fluorocarbon coating of claim 1.

13. A method for controlling the surface energy of a microchannel, comprising:

introducing into the microchannel a chemical mixture comprising an acid catalyst and a functionalized silane agent in a solvent, w herein the chemical mixture is contacted with the microchannel walls for a predetermined period of time and at a fixed temperature to control the extent to which the walls are coated.

14. The method of claim 13, wherein the silane agent is functionalized with an uncharged fluorinated alkane and alkoxy or halogen ligands.

15. The method of claim 13, wherein the halogen ligands are chloro ligands.

16. The method of claim 13, wherein the uncharged fluorinated alkane is an uncharged C₃-C₁₀ fluorinated alkane chain.

17. The method of claim 14, wherein alkoxy is methoxy, ethoxy, acetoxy, methoxyethoxy or methoxymethyl.

18. The method of claim 13, wherein the silane agent is (tridecafluoro-1,1,2,2-tetrahydrooctyl) triethoxysilane.

19. The method of claim 13, wherein the period of time is in the range of from about 2 to about 120 minutes.

20. The method of claim 13, wherein the fixed temperature is a temperature in the range of from about 50 to 90°

C.

21. The method of claim 20, wherein the temperature is about 70°

C.