Coating Containing Chain-Like Silica Nanoparticles Having Highly-Transparent Hydrophobic Surfaces

A nanoparticle coating provides transparent, hydrophobic surface coverage on charged substrates using electrostatically bound chain-like silica assemblies.
Problem:
Transparent surfaces often need water repellency without sacrificing optical transmission. Rough structures used for hydrophobicity can increase light scattering and reduce clarity. Multilayer nanoparticle coatings can also become difficult to de-wet after wetting events. A coating is needed that combines transparency, hydrophobicity, and thin surface coverage.
Solution:
The technology uses anisotropic chain-like silica nanoparticles adhered to a substrate by electrostatic charge. The coating forms surface topography while covering less than about 45% of the substrate surface. Claimed embodiments transmit greater than about 90% of incident light from about 400 nm to about 800 nm. The coating is also hydrophobic and can substantially resist condensation or fogging.
Technology:
The coating includes linked arrays of silica nanoparticles with chain dimensions of about 100 nm to 1200 nm and diameters of about 20 nm to 80 nm. The substrate surface carries net positive surface-active moieties, and the silica assemblies are held by electrostatic interactions. Preparation can include substrate functionalization, nanoparticle deposition, and washing with solvent. Deposition can be performed by dip coating, drop casting, or slot coating.
Advantages:

• Combines hydrophobic behavior with high visible-light transmission
• Uses thin surface coverage rather than dense multilayer packing
• Adheres through electrostatic interactions on functionalized substrates
• Can substantially resist condensation, fogging, or both

Applications:

• Windows: Provides a transparent hydrophobic coating for glass surfaces used in outdoor conditions.
• Solar panels: Applies a light-transmitting hydrophobic coating to panel surfaces where reduced soiling and water removal are desired.
• Anti-fogging surfaces: Uses a coating that substantially resists condensation, fogging, or both.
• Polymer and fabric surfaces: Extends hydrophobic transparent coating approaches to polymer, plastic, or fabric substrates identified in the technology.

Intellectual Property:

• US 11,365,333

Stage of Development:

• Prototype

Desired Partnerships:

• Licensing
• Research collaboration

Reference Media:

• Wu G. et al.; Adv. Mater. Interfaces 2020 Sept 13; 8(2): 2000681. 

3A is a water droplet (3 μL) on a coated glass substrate with a water contact angle of 169°. FIG. 3B is an optical image showing a coated glass slide with 20 μL water droplets on top and in front of a LCD screen. FIG. 3C is a schematic illustration of a water droplet sitting on the nanoparticle coating.
Docket: 15-7519