Antireflective synthetic brochosomal coatings

Patent metadata

Field	Value
Publication number	US-2021181380-A1
Application number	US-202117145749-A
Country	US
Kind code	A1
Filing date	Jan 11, 2021
Priority date	Apr 5, 2017
Publication date	Jun 17, 2021
Grant date	—

Abstract

Synthetic brochosomes can be prepared by disposing a monolayer of first polymer microspheres on a substrate and forming a layer of metal on the monolayer of the first polymer microspheres. A monolayer of second polymer microspheres is then disposed on the layer of metal to form a template. The second polymer microspheres are smaller than the first polymer microspheres. A brochosome material is then electrodeposited on the template. The brochosome material is selected from the group consisting of a metal, a metal oxide, a polymer or a hybrid thereof. The first polymer microspheres and the second polymer microspheres are then removed to form a coating of synthetic brochosomes of the brochosome material on the substrate.

First claim

What is claimed is:

1 . A method of making a synthetic brochosome, the method comprising:
a) forming a spherical portion of a material that is capable of receiving an electrodeposition-compatible material, the spherical portion having an interior surface, the interior surface having a shape that is at least a portion of a first sphere having a first diameter; and b) radially depositing a plurality of outgrowths of the electrodeposition-compatible material from the spherical portion, thereby forming the synthetic brochosome, the plurality of outgrowths defining a plurality of indentations, the radially depositing being outward from the interior surface and around a plurality of removable structures, each indentation having a shape that is a negative imprint of one of the plurality of removable structures, the plurality of indentations each having a second diameter, wherein the second diameter is smaller than the first diameter.

2 . The method of claim 1 , wherein the first diameter is in a range from 1 μm to 10 μm.

3 . The method of claim 1 , wherein the second diameter is in a range from 100 nm to 1 μm.

4 . The method of claim 1 , wherein the plurality of indentations form a honeycomb pattern.

5 . The method of claim 1 , wherein a ratio of the second diameter to the first diameter is less than 0.35.

6 . The method of claim 1 , wherein each spherical portion has a first radius, and each indentation has a second radius,
wherein the first radius is less than 9 times a predetermined wavelength of light, and the first radius is greater than 1.4 times the predetermined wavelength of light, and wherein the second radius is less than 2 times the predetermined wavelength of light, and the second radius is greater than 0.5 times the predetermined wavelength of light.

7 . The method of claim 6 , wherein the predetermined wavelength of light falls within at least one of the following regions:
ultraviolet light region; visible light region; or near infrared light region.

8 . The method of claim 1 , wherein the plurality of indentations includes at least 7 indentations.

9 . A method of making an antireflective coating, the method comprising:
repeating the method of claim 1 a plurality of times to make a plurality of synthetic brochosomes; and disposing the plurality of synthetic brochosomes in a layer on a substrate, wherein the layer is a monolayer.

10 . The method of claim 9 , wherein the coating has a reflectance of less than 10% at a wavelength in a range from 250 nm to 2000 nm.

11 . The method of claim 9 , wherein the plurality of synthetic brochosomes are arranged to form a pattern, the pattern being substantially a honeycomb pattern.

12 . A method of preparing synthetic brochosomes, the method comprising:
disposing a layer of first removable spheres on a substrate; forming a layer of an electrically conductive material on the layer of first removable spheres; disposing a layer of second removable spheres on the layer of electrically conductive material to form a template, the second removable spheres being smaller the first removable spheres; electrodepositing a brochosome material on the template, and removing the first removable spheres and the second removable spheres to form synthetic brochosomes of the brochosome material.

13 . The method of claim 12 , further comprising isotropic etching of the first removable spheres prior to electrodepositing the brochosome material and removing the first and the removable spheres to reduce the size of the first and removable spheres, thereby releasing the synthetic brochosomes from the substrate following the removing of the first and second removable spheres.

14 . The method of claim 12 , wherein disposing the layer of first spheres on the substrate comprises:
disposing the first removable spheres on an intermediate substrate; forming a free-standing monolayer of the first removable spheres at an interface of a liquid and air by immersing the intermediate substrate in the liquid, the liquid having a specific gravity greater than that of the first removable spheres and the liquid being substantially inert to the first removable spheres; and transferring the free-standing monolayer onto the substrate.

15 . The method of claim 14 , wherein the first removable spheres comprise polystyrene and the liquid is an aqueous medium.

16 . The method of claim 12 , wherein
the brochosome material comprises a metal, and during electrodepositing the brochosome material, the electrically conductive material of the template is used as a cathode.

17 . The method of claim 12 , wherein
the brochosome material is a metal oxide or a conducting polymer, and during electrodepositing the brochosome material, the electrically conductive material of the template is used as an anode.

18 . The method of claim 12 , wherein the first removable spheres have a length scale in a range from 1 μm to 10 μm.

19 . The method of claim 12 , wherein the second removable spheres have a length scale of 100 nm to 1 μm.

20 . The method of claim 12 , wherein a ratio (R t /R b ) of a radius of R t of the second removable spheres to a radius R b of the first removable spheres is less than 0.35.

Assignees

• Penn State Res Found

Inventors

• Wong Tak-Sing
• Yang Shikuan
• Sun Nan
• Boschitsch Birgitt

Classifications

• C25D13/06

  with polymers {(not used, see C09D5/44)} · CPC title

• C25D5/605

  Surface topography of the layers, e.g. rough, dendritic or nodular layers · CPC title

• B22F1/18

  Non-metallic particles coated with metal · CPC title

• G02B1/118

  having sub-optical wavelength surface structures designed to provide an enhanced transmittance, e.g. moth-eye structures · CPC title

• B22F1/05

  Metallic powder characterised by the size or surface area of the particles · CPC title