Method and device for restoring and maintaining superhydrophobicity under liquid

Patent metadata

Field	Value
Publication number	US-9314818-B2
Application number	US-201113811272-A
Country	US
Kind code	B2
Filing date	Jul 22, 2011
Priority date	Jul 27, 2010
Publication date	Apr 19, 2016
Grant date	Apr 19, 2016

Abstract

A superhydrophobic surface includes a plurality of microfeatures disposed on a substrate and a gas generator disposed within the microfeatures, the gas generator configured to generate a gas within the microfeatures. Gas is generated within the microfeatures when at least a portion of the microfeatures is in a wetted state to restore the microfeatures to a dewetted state. Gas generation is self-regulating in that gas generation automatically starts when a wetted condition exists and stops when sufficient gas has been generated to recover a dewetted state that restores superhydrophobicity.

First claim

What is claimed is:

1. A superhydrophobic surface substantially immersed in water comprising:
a substrate substantially immersed in the water;
a plurality of microfeatures in the shape of posts or grates extending away from the substrate and substantially separated from one another by a distance and oriented substantially orthogonal to a surface of the substrate, wherein adjacent microfeatures define spaces there between;
a plurality of gas generators disposed on or embedded in the substrate or microfeatures;
wherein each gas generator is configured to automatically generate one of hydrogen gas (H 2 ) or oxygen gas (O 2 ) within the respective space when water invades the space and contacts the gas generator and wherein gas generation automatically stops when water is expelled from the space by the generated hydrogen gas (H 2 ) or oxygen gas (O 2 ); and
wherein the gas fraction, contact angles, and height (H) to pitch (L) ratio of the microfeatures are within a range that directs the generated hydrogen gas (H 2 ) or oxygen gas (O 2 ) to grow into a substantially continuous layer of gas filling the spaces between the microfeatures rather than allowing the generated hydrogen gas (H 2 ) or oxygen gas (O 2 ) to form individual bubbles of gas leaving the superhydrophobic surface during filling of the spaces.

2. The superhydrophobic surface of claim 1 , wherein the substrate further comprises a plurality of nanofeatures disposed thereon.

3. The superhydrophobic surface of claim 1 , wherein the microfeatures further comprises a plurality of nanofeatures disposed thereon.

4. The superhydrophobic surface of claim 1 , wherein the gas generators comprise electrodes coupled to a source of electrical power.

5. The superhydrophobic surface of claim 4 , wherein the electrodes are disposed on or embedded in the surface of the substrate or microfeatures.

6. The superhydrophobic surface of claim 1 , wherein the gas generators comprise a chemical reactant.

7. The superhydrophobic surface of claim 1 , wherein the surface is located on the hull of a vessel.

8. The superhydrophobic surface of claim 1 , wherein the surface is located on an interior surface of a pipe.

9. The superhydrophobic surface of claim 1 , wherein the gas generators comprise a metal.

10. The superhydrophobic surface of claim 1 , wherein the superhydrophobic surface has a gas fraction greater than or equal to 80%.

11. The superhydrophobic surface of claim 1 , wherein the superhydrophobic surface has a gas fraction greater than or equal to 90%.

12. A superhydrophobic surface substantially immersed in water comprising:
a substrate substantially immersed in the water;
a plurality of microfeatures in the shape of posts or grates extending away from the substrate and substantially separated from one another by a distance and oriented substantially orthogonal to a surface of the substrate, wherein adjacent microfeatures define spaces there between;
a plurality of gas generating electrodes disposed on or embedded in the surface of the substrate or microfeatures;
a power source coupled to the gas generating electrodes, wherein the gas generating electrodes are configured to automatically generate one of hydrogen gas (H 2 ) or oxygen gas (O 2 ) within the respective space when the water invades the space and contacts the gas generating electrode and wherein hydrogen gas (H 2 ) or oxygen gas (O 2 ) generation automatically stops when water is expelled from the space by the generated hydrogen gas (H 2 ) or oxygen gas (O 2 ); and
wherein the gas fraction, contact angles, and height (H) to pitch (L) ratio of the microfeatures are within a range that directs the generated hydrogen gas (H 2 ) or oxygen gas (O 2 ) to grow into a substantially continuous layer of gas filling the spaces between the microfeatures rather than allowing the generated hydrogen gas (H 2 ) or oxygen gas (O 2 ) to form individual bubbles of gas leaving the superhydrophobic surface during filling of the spaces.

13. The superhydrophobic surface of claim 12 , wherein the substrate further comprises a plurality of nanofeatures disposed thereon.

14. The superhydrophobic surface of claim 12 , wherein the microfeatures further comprises a plurality of nanofeatures disposed thereon.

15. The superhydrophobic surface of claim 12 , wherein the superhydrophobic surface has a gas fraction greater than or equal to 80%.

16. The superhydrophobic surface of claim 12 , wherein the superhydrophobic surface has a gas fraction greater than or equal to 90%.

Assignees

• Kim Chang-Jin
• Lee Choongyeop
• Univ California

Inventors

• Kim Chang-Jin
• Lee Choongyeop

Classifications

• B05C7/00

  Apparatus specially designed for applying liquid or other fluent material to the inside of hollow work · CPC title

• Y10T428/24355

  Continuous and nonuniform or irregular surface on layer or component [e.g., roofing, etc.] · CPC title

• B82Y30/00

  Nanotechnology for materials or surface science, e.g. nanocomposites · CPC title

• C09D5/1681 Primary

  Antifouling coatings characterised by surface structure, e.g. for roughness effect giving superhydrophobic coatings or Lotus effect · CPC title

• C25D17/00

  Constructional parts, or assemblies thereof, of cells for electrolytic coating · CPC title