Transparent durable superhydrophobic ceramic coating

Patent metadata

Field	Value
Publication number	US-10253190-B2
Application number	US-201615224840-A
Country	US
Kind code	B2
Filing date	Aug 1, 2016
Priority date	Aug 25, 2015
Publication date	Apr 9, 2019
Grant date	Apr 9, 2019

Abstract

A superhydrophobic ceramic coating that is transparent and durable includes a dispersion of a multiplicity of silica nanoparticles stacked to form a topography that is rough that is infused with and conformally coated with a sol-gel glass matrix that has a fluoroalkyl silane or an alkyl silane monolayer on the surface of the coating. The silica nanoparticles do not scatter light to a large extent as they are sufficiently small and free of aggregation. The sol-gel glass is formed from a trialkoxysilane precursor and applied to the stacked silica nanoparticles to retain the rough topography of the deposited nanoparticles.

First claim

We claim:

1. A durable and transparent superhydrophobic ceramic coating comprising:
a stacked structure, the stacked structure comprising a random dispersion of silica nanoparticles, the stacked structure being formed by 2 to 5 depositions of a solution comprising from 0.1 to 1.0% by weight of silica nanoparticles, the stacked structure having a topography comprising peaks and valleys, wherein a majority of dimensions of the peaks and valleys are less than 400 nm;
a sol-gel glass matrix, the sol-gel glass matrix coating the stacked structure with a degree of conformity sufficient to retain the topography of the stacked structure, the sol-gel glass matrix binding the random dispersion of silica nanoparticles, the sol-gel glass matrix being formed by hydrolysis and condensation a sol-gel formulation comprising 3 to 4% by weight of a tetraalkoxysilane; and
a monolayer bound to the sol-gel glass matrix, the monolayer comprising at least one monolayer precursor selected from a fluoroalkyl silane, an alkyl silane, and combinations thereof,
wherein the durable and transparent superhydrophobic coating has a transmittance of at least 80%, and
wherein the durable and transparent superhydrophobic coating retains a contact angle greater than 140° after a 70 cycle linear abrasion test performed with a windshield wiper at a force of 1.5 ounce/inch.

2. The durable and transparent superhydrophobic ceramic coating according to claim 1 , wherein the tetraalkoxysilane is tetraethoxysilane.

3. The durable and transparent superhydrophobic ceramic coating according to claim 1 , wherein the tetraalkoxysilane is tetramethoxysilane.

4. The durable and transparent superhydrophobic ceramic coating according to claim 1 , wherein said silica nanoparticles are 20 to 100 nm in cross-section.

5. The durable and transparent superhydrophobic ceramic coating according to claim 1 , wherein said silica nanoparticles are spherical in shape.

6. The durable and transparent superhydrophobic ceramic coating according to claim 1 , wherein said fluoroalkyl silane has the structure F 3 C(CF 2 ) x CH 2 CH 2 Si where x is 2 to 20.

7. A method of preparing a durable and transparent superhydrophobic ceramic coating comprising:
a stacked structure, the stacked structure comprising a random dispersion of silica nanoparticles, the stacked structure being formed by 2 to 5 depositions of a solution comprising from 0.1 to 1.0% by weight of silica nanoparticles, the stacked structure having a topography comprising peaks and valleys, wherein a majority of dimensions of the peaks and valleys are less than 400 nm;
a sol-gel glass matrix, the sol-gel glass matrix coating the stacked structure with a degree of conformity sufficient to retain the topography of the stacked structure, the sol-gel glass matrix binding the random dispersion of silica nanoparticles, the sol-gel glass matrix being formed by hydrolysis and condensation a sol-gel formulation comprising 3 to 4% by weight of a tetraalkoxysilane; and
a monolayer bound to the sol-gel glass matrix, the monolayer comprising at least one monolayer precursor selected from a fluoroalkyl silane, an alkyl silane, and combinations thereof,
wherein the durable and transparent superhydrophobic coating has a transmittance of at least 80%, and
wherein the durable and transparent superhydrophobic coating retains a contact angle greater than 140° after a 70 cycle linear abrasion test performed with a windshield wiper at a force of 1.5 ounce/inch,

the method comprising,
providing a substrate;
performing 2 to 5 depositions of the solution comprising from 0.1 to 1.0% by weight of silica nanoparticles onto the substrate to form the stacked structure;
infusing the stacked structure with the sol-gel formulation comprising 3 to 4% by weight of the tetraalkoxysilane;
performing the hydrolysis and condensation of the sol-gel formulation to form the sol-gel glass matrix; and
contacting the sol-gel glass matrix with the at least one monolayer precursor to form the monolayer bound to the sol-gel glass matrix.

8. The method of claim 7 , wherein said silicon nanoparticles are 20 to 100 nm in cross-section.

9. The method of claim 7 , wherein said silica nanoparticles are spherical in shape.

10. The method of claim 7 , wherein said tetraalkoxysilane is tetramethoxysilane.

11. The method of claim 7 , wherein said tetraalkoxysilane is tetraethoxysilane.

12. The method of claim 7 , wherein said fluoroalkyl silane coupling agent is F 3 C(CF 2 ) x CH 2 CH 2 SiCl 3 where x is 2 to 20.

Assignees

• Univ Florida

Inventors

• Sigmund Wolfgang M
• Hung Yung-Chieh

Classifications

• C03C2217/213

  SiO2 · CPC title

• C23C18/00

  Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating · CPC title

• C09D183/08

  containing silicon bound to organic groups containing atoms other than carbon, hydrogen, and oxygen · CPC title

• C09D7/80

  Processes for incorporating ingredients · CPC title

• C09D7/67

  Particle size smaller than 100 nm · CPC title