Methods for Preparing a Superomniphobic Coating

Patent metadata

Field	Value
Publication number	US-2021331967-A1
Application number	US-202016855378-A
Country	US
Kind code	A1
Filing date	Apr 22, 2020
Priority date	Apr 22, 2020
Publication date	Oct 28, 2021
Grant date	—

Abstract

A method for preparing an optically transparent, superomniphobic coating on a substrate, such as an optical substrate, is disclosed. The method includes providing a glass layer disposed on a substrate, the glass layer having a first side adjacent the substrate and an opposed second side, the glass layer comprising 45-85 wt. % silicon oxide in a first glass phase and 10-40 wt. % boron oxide in a second glass phase, such that a glass layer has a composition in a spinodal decomposition region. The method further includes heating the second side of the glass layer to form a phase-separated portion of the layer, the phase-separated portion comprising an interpenetrating network of silicon oxide domains and boron oxide domains, and removing at least a portion of the boron oxide domains from the phase-separated portion to provide a graded layer disposed on the substrate. The graded layer has a first side disposed adjacent the substrate, the first side comprising 45-85 wt. % silicon oxide and 10-40 wt. % boron oxide, and opposite the first side, a porous second side comprising at least 45 wt. % silicon oxide and no more than 5 wt. % boron oxide.

First claim

1 . A method for preparing a coating, comprising
providing a glass layer disposed on a substrate, the glass layer having a first side adjacent the substrate and an opposed second side, the glass layer comprising 45-85 wt. % silicon oxide in a first glass phase and 10-40 wt. % boron oxide in a second glass phase, such that the glass layer has a composition in a spinodal decomposition region; heating the second side of the glass layer to form a phase-separated portion of the layer, the phase-separated portion comprising an interpenetrating network of silicon oxide domains and boron oxide domains; and removing at least a portion of the boron oxide domains from the phase-separated portion to provide a graded layer disposed on the substrate, the graded layer having
a first side disposed adjacent the substrate, the first side comprising 45-85 wt. % silicon oxide and 10-40 wt. % boron oxide, and
opposite the first side, a porous second side comprising at least 45 wt. % silicon oxide and no more than 5 wt. % boron oxide.

2 . The method of claim 1 , wherein heating the second side comprises heating with a flash lamp.

3 . The method of claim 1 , wherein heating the second side comprises heating with a pulsed laser.

4 . The method of claim 1 , wherein removing the phase-separated boron oxide domains comprises selectively etching for a period of time sufficient to remove substantially all of the boron oxide domains.

5 . The method of claim 4 , comprising etching with an acid.

6 . The method of claim 1 , further comprising
before heating the second side, depositing a diffusing layer onto the second side of the glass layer; and after forming the phase-separated portion, removing the diffusing layer.

7 . The method of claim 6 , wherein the diffusing layer comprises carbon.

8 . The method of claim 6 , wherein the diffusing layer has a thickness in the range of 5 nm to 500 nm.

9 . The method of claim 1 , further comprising depositing a hydrophobic silane layer onto at least a portion of the second side of the graded layer.

10 . The method of claim 9 , wherein the deposited silane is covalently linked to the phase-separated silicon oxide domains of the graded layer.

11 . The method of claim 1 , wherein the graded layer has a thickness within the range of 300 nm to 1 μm.

12 . The method of claim 1 , wherein the graded layer comprises an inner region adjacent the first side, a middle region adjacent the inner region, and an outer region adjacent the middle region and the second side, and wherein
the inner region is substantially non-porous; the middle region comprises a first plurality of pores, wherein the average pore size of the first plurality increases along a gradient from the inner region to the outer region; and the outer region comprises a second plurality of pores.

13 . The method of claim 12 , wherein
the inner region comprises at least 80 wt. % of a non-phase-separated borosilicate glass, and at least about 80 wt. % of the silicon oxide present in the outer region comprises amorphous silica.

14 . The method of claim 12 , wherein the average pore size of the first plurality of pores increases along the gradient from less than 25 nm, to 50 nm to 180 nm.

15 . The method of claim 12 , wherein the average pore size of the second plurality of pores is within the range of 50 nm to 180 nm.

16 . The method of claim 12 , wherein
the inner region has a thickness of less than 250 nm; the middle region has a thickness within the range of 250 nm to 750 nm; and the outer region has a thickness of less than 250 nm.

17 . The method of claim 1 , further comprising disposing aerogel in at least a portion of the pores of the graded layer.

18 . The method of claim 17 , wherein disposing aerogel comprises
forming a sol-gel in at least a portion of the pores of the graded layer; and drying the sol-gel to form an aerogel.

19 . The method of claim 17 , wherein disposing aerogel comprises
disposing a suspension of aerogel nanoparticles in at least a portion of the pores of the graded layer; and drying the suspension.

20 . An article prepared according to the method of claim 1 .

Assignees

• Waymo Llc

Inventors

• Simpson John T

Classifications

• C03C2218/33

  by etching · CPC title

• C03C3/089

  containing boron · CPC title

• C03C2217/91

  Coatings containing at least one layer having a composition gradient through its thickness · CPC title

• C03C17/02 Primary

  with glass (C03C17/34, C03C17/44 take precedence) · CPC title

• C03C2217/42

  consisting of particles only · CPC title