Superhydrophobic coatings and methods for their preparation

• US 9,675,994 B2
• Filed: 06/01/2012
• Issued: 06/13/2017
• Est. Priority Date: 06/01/2011
• Status: Active Grant

• Current Assignee: University of North Carolina At Chapel Hill (University of North Carolina System)
• Original Assignee: Kwangwoon University Industry, University of North Carolina At Chapel Hill (University of North Carolina System)
• Inventors: Shin, Jae Ho, Privett, Ben, Youn, Jonghae, Schoenfisch, Mark H.
• Primary Examiner(s): Rodriguez, Michael P
• Application Number:
  US14/122,378
• Publication Number:
  US 20140238263A1
• Time in Patent Office: 1,838 Days
• Field of Search: None
• CPC Class Codes: B05D 1/02 performed by spraying
• CPC Class Codes: C01B 33/128 by acidic treatment of aqueous silicate solutions
• CPC Class Codes: C01B 33/142 by acidic treatment of silicates
• CPC Class Codes: C01B 33/143 of aqueous solutions of silicates
• CPC Class Codes: C09D 1/00 Coating compositions, e.g. paints, varnishes or lacquers, based on inorganic substances

Abstract

Superhydrophobic coatings and compositions and methods for preparing superhydrophobic coatings and compositions are described herein whereby the coatings and compositions are prepared under mild conditions, yet the methods are amenable to chemical functionalization of the coatings and components therein. The methods are useful for tuning and optimizing the physical properties of the coatings. In an embodiment, the coatings comprise nanostructured fluorinated silica colloids.

Claims

1. A method of preparing a coating, comprising:

a) contacting at room temperature, not including any heat generated by the contacting itself, a silica-containing colloid with two or more silanes to prepare a first colloid mixture, wherein one of the silanes is methyltrimethoxysilane (MTMOS) and at least one of the silanes is a fluoroalkoxysilane,

b) contacting at room temperature, not including any heat generated by the contacting itself, said first colloid mixture with an acid, wherein a superhydrophobic coating is prepared;

wherein no heat, besides any heat generated by the contacting, is added in either step a) or step b); and

wherein said MTMOS is present in a molar excess amount relative to said fluoroalkoxysilane.

2. The method of claim 1, wherein said colloid comprises silica nanoparticles.

3. The method of claim 1, wherein said fluoroalkoxysilane is (heptadecafluoro-1,1,2,2-tetrahydrodecyl)trimethoxysilane.

4. The method of claim 1, wherein at least one of said silanes is a backbone silane selected from the group consisting of butyltrimethoxysilane (BTMOS), tetramethylorthosilicate (TMOS), tetraethylorthosilicate (TEOS) or their combinations thereof.

5. The method of claim 1, further comprising:

c) contacting the product of said b) with a solid substrate, wherein no plasma etching, chemical etching, or chemical vapor deposition is performed.

6. The method of claim 5, wherein said solid substrate is selected from the group consisting of medical devices, plumbing fixtures, condenser coils, optical surfaces, boat hulls and aircraft.

7. The method of claim 5, wherein said contacting comprises spray coating.

8. A method of reducing microbial adhesion, condensation or ice buildup, comprising:

contacting the coating prepared according to claim 1 with a solid substrate, wherein no plasma etching, chemical etching, or chemical vapor deposition is performed.

9. The method of claim 8, wherein said microbial adhesion is a bacterial adhesion.

10. The method of claim 8, wherein said microbial adhesion is a fungal adhesion.

11. The method of claim 10, wherein said fungal adhesion comprises an adhesion of a Candida species.

12. The method of claim 8, wherein said contacting comprises spray coating.

13. A method of coating a substrate comprising:

contacting said substrate at room temperature by spray coating a composition comprising, nanostructured fluorinated silica colloids, and a fluoroalkoxysilane covalently linked to at least one additional backbone silane to prepare a coated substrate;

wherein said additional backbone silane is methyltrimethoxysilane (MTMOS);

wherein no heat, besides any heat generated by the contacting, is added during the spray coating; and

wherein no plasma etching, chemical etching, or chemical vapor deposition is performed during the spray coating.