Structural coatings with dewetting and anti-icing properties, and coating precursors for fabricating same

Patent metadata

Field	Value
Publication number	US-9546280-B2
Application number	US-201213708642-A
Country	US
Kind code	B2
Filing date	Dec 7, 2012
Priority date	Dec 7, 2012
Publication date	Jan 17, 2017
Grant date	Jan 17, 2017

Abstract

Variations of this invention provide durable, impact-resistant structural coatings that have both dewetting and anti-icing properties. The coatings in some embodiments possess a self-similar structure that combines a low-cost matrix with two feature sizes that are tuned to affect the wetting of water and freezing of water on the surface. Dewetting and anti-icing performance is simultaneously achieved in a structural coating comprising multiple layers, wherein each layer includes (a) a continuous matrix; (b) discrete templates dispersed that promote surface roughness to inhibit wetting of water; and (c) nanoparticles that inhibit heterogeneous nucleation of water. These structural coatings utilize low-cost, lightweight, and environmentally benign materials that can be rapidly sprayed over large areas using convenient coating processes. The presence of multiple layers means that if the surface is damaged during use, freshly exposed surface will expose a coating identical to that which was removed, for extended lifetime.

First claim

What is claimed is:

1. A structural coating that inhibits wetting and freezing of water, said structural coating comprising a plurality of layers, wherein each layer includes:
(a) a substantially continuous matrix comprising a hardened material;
(b) a plurality of discrete templates dispersed within said matrix, wherein said discrete templates are chemically different than said continuous matrix, wherein said discrete templates have an average template length scale from about 75 nanometers to about 10 microns, wherein said discrete templates promote surface roughness at a surface of said layer, and wherein said surface roughness inhibits wetting of water;
(c) porous voids surrounding at least a portion of said discrete templates, wherein said porous voids have an average pore length scale from about 50 nanometers to about 5 microns, and wherein said average pore length scale is less than said average template length scale; and
(d) a plurality of nanoparticles with an average size of about 50 nanometers or less within said matrix, wherein said nanoparticles are disposed on pore surfaces of said porous voids, wherein said nanoparticles are chemically different than said discrete templates, and wherein said nanoparticles inhibit heterogeneous nucleation of water,
wherein said structural coating has a thickness from about 5 microns to about 500 microns.

2. The structural coating of claim 1 , wherein said thickness is from about 50 microns to about 100 microns.

3. The structural coating of claim 1 , wherein said discrete templates are uniformly dispersed within said matrix.

4. The structural coating of claim 1 , wherein at least some of said discrete templates are anisotropic.

5. The structural coating of claim 1 , wherein at least some of said discrete templates are geometrically asymmetric.

6. The structural coating of claim 1 , wherein said discrete templates have an average template length scale from about 100 nanometers to about 3 microns.

7. The structural coating of claim 1 , wherein said structural coating has an average density of discrete templates from about 0.1 to about 0.5 g/cm 3 .

8. The structural coating of claim 1 , wherein said porous voids have an average pore length scale from about 50 nanometers to about 900 nanometers.

9. The structural coating of claim 1 , wherein said structural coating has a void density from about 10 11 to about 10 13 voids per cm 3 .

10. The structural coating of claim 1 , wherein said structural coating has a porosity from about 20% to about 70%.

11. The structural coating of claim 1 , wherein said nanoparticles have an average particle size from about 5 nanometers to about 50 nanometers.

12. The structural coating of claim 1 , wherein at least a portion of said plurality of nanoparticles is disposed on or adjacent to surfaces of said discrete templates.

13. The structural coating of claim 12 , wherein said nanoparticles are chemically and/or physically bonded to or associated with said discrete templates.

14. The structural coating of claim 1 , wherein said hardened material comprises a crosslinked polymer selected from the group consisting of polyurethanes, epoxies, acrylics, phenolic resins including urea-formaldehyde resins and phenol-formaldehyde resins, urethanes, siloxanes, and combinations thereof.

15. The structural coating of claim 1 , wherein said matrix further comprises one or more additives selected from the group consisting of fillers, colorants, UV absorbers, defoamers, plasticizers, viscosity modifiers, density modifiers, catalysts, and scavengers.

16. The structural coating of claim 1 , wherein said discrete templates comprise an inorganic templating material selected from the group consisting of calcium carbonate, sodium chloride, sodium bromide, potassium chloride, tin (II) fluoride, iron oxides, and combinations thereof.

17. The structural coating of claim 16 , wherein said discrete templates comprise anisotropic calcium carbonate particles.

18. The structural coating of claim 1 , wherein said discrete templates are surface-modified with a compound selected from the group consisting of fatty acids, silanes, alkyl phosphonates, alkyl phosphonic acids, alkyl carboxylates, and combinations thereof.

19. The structural coating of claim 1 , wherein said nanoparticles comprise a nanomaterial selected from the group consisting of silica, alumina, titania, zinc oxide, carbon, graphite, polytetrafluoroethylene, polystyrene, polyurethane, silicones, and combinations thereof.

20. The structural coating of claim 1 , wherein said nanoparticles are surface-modified with a hydrophobic material selected from alkylsilanes, fluoroalkylsilanes, alkyldisilazanes, or combinations thereof.

21. The structural coating of claim 1 , wherein said structural coating is characterized by a water contact angle of about 110° or higher.

22. The structural coating of claim 1 , wherein said structural coating is characterized by a water contact angle of about 150° or higher.

23. The structural coating of claim 1 , wherein said structural coating is characterized by a water roll-off angle of about 10° or less.

24. The structural coating of claim 1 , wherein said structural coating is characterized by an ice melting-point depression to at least −10° C.

25. The structural coating of claim 1 , wherein said structural coating is characterized by a kinetic delay of water freezing of at least 75 seconds.

26. A structural coating that inhibits wetting and freezing of water, said structural coating comprising:
(a) a substantially continuous matrix comprising a hardened material;
(b) a plurality of discrete templates dispersed within said matrix, wherein said discrete templates are chemically different than said continuous matrix, wherein said discrete templates have an average template length scale from about 75 nanometers to about 10 microns, wherein said discrete templates promote surface roughness at a surface of said structural coating, and wherein said surface roughness inhibits wetting of water; and
(c) a plurality of nanoparticles with an average particle size from about 5 nanometers to about 50 nanometers within said matrix, wherein said nanoparticles are chemically different than said discrete templates, and wherein said nanoparticles inhibit heterogeneous nucleation of water,
wherein said structural coating has a thickness from about 5 microns to about 500 microns; and
wherein said structural coating contains porous voids that are uniformly distributed within said matrix, with a void density from about 10 11 to about 10 13 voids per cm 3 .

27. The structural coating of claim 26 , wherein said thickness is from about 25 microns to about 200 microns.

28. The structural coating of claim 26 , wherein said thickness is less than 25 microns.

29. The structural coating of claim 26 , wherein said average template length scale is from about 100 nanometers to about 3 microns.

30. The structural coating of claim 26 , wherein said porous voids have an average pore length scale from about 50 nanometers to about 5 microns, and wherein said average pore length scale is less than said average template length scale.

31. The structural coating of claim 30 , wherein said average pore length scale is from about 50 nanometers to about 1 micron.

32. The structural coat

Assignees

• Nowak Andrew P
• Gross Adam F
• Bartl Michael H
• Hrl Lab Llc

Inventors

• Nowak Andrew P
• Gross Adam F
• Bartl Michael H

Classifications

• Y10T428/24421

  Silicon containing · CPC title

• Y10T428/24413

  Metal or metal compound · CPC title

• Y10T428/24405

  Polymer or resin [e.g., natural or synthetic rubber, etc.] · CPC title

• Y10T428/24388

  Silicon containing coating · CPC title

• Y10T428/2438

  Coated · CPC title