Porous titanium dioxide coatings and methods of forming porous titanium dioxide coatings having improved photocatalytic activity
View Patent ↗Methods for forming porous anatase titanium dioxide coatings are disclosed. Sol-gel compositions are prepared having at least one porosity agent, are applied to a substrate, and at least one porosity agent is removed. Porous anatase titanium dioxide coatings having at least one of improved antimicrobial properties, self-cleaning properties, hydrophilicity, and/or temperability are also disclosed. Substrates comprising such coatings are also disclosed.
1. A method of forming a porous anatase titanium dioxide coating on a substrate, comprising:
preparing a titanium dioxide sol-gel composition comprising at least one porosity agent;
coating the substrate with the sol-gel composition; and
removing the porosity agent;
wherein the porosity agent is removed by heating the coated substrate at a temperature greater than about 600° C. to form the anatase titanium dioxide coating from the sol-gel composition;
wherein the porosity agent is present in the sol-gel composition in an amount comprising at least 5 wt % of the total weight of the sol-gel composition.
2. The method of claim 1 , wherein the substrate comprises a glass substrate.
3. The method of claim 2 , wherein the glass substrate is chosen from clear or low-iron glass.
4. The method of claim 1 , wherein the porosity agent is removed by heating the coated substrate at a temperature greater than about 625° C.
5. The method of claim 1 , wherein the preparing of the titanium dioxide sol-gel composition includes preparing a sol-gel composition that comprises (1) a titanium alkoxide or a titanium chloride, and (2) the porosity agent.
6. The method of claim 1 , wherein said porosity agent is polyethylene glycol.
7. The method of claim 6 , wherein the polyethylene glycol is present in the sol-gel composition in an amount comprising at least about 10 wt % of the total weight of the sol-gel composition.
8. The method of claim 7 , wherein the polyethylene glycol is present in the sol-gel composition in an amount comprising at least about 20 wt % of the total weight of the sol-gel composition.
9. A method of improving at least one of antimicrobial properties, self-cleaning properties, hydrophilicity, and temperability of a titanium dioxide coating, comprising:
preparing a titanium dioxide sol-gel composition comprising at least one porosity agent;
coating a substrate with the sol-gel composition; and
heating the coated substrate to remove the porosity agent without forming rutile phase titanium dioxide;
wherein the porosity agent is removed by heating the coated substrate at a temperature greater than about 600° C. to form an anatase titanium dioxide coating from the sol-gel composition;
wherein the porosity agent is present in the sol-gel composition in an amount comprising at least 5 wt % of the total weight of the sol-gel composition.
10. The method of claim 9 , wherein said substrate is chosen from clear or low-iron glass.
11. The method of claim 9 , wherein the anatase titanium dioxide coating is a pure anatase phase titanium dioxide coating.
12. The method of claim 9 , wherein the preparing of the titanium dioxide sol-gel composition includes preparing a sol-gel composition that comprises (1) a titanium alkoxide or a titanium chloride, and (2) the porosity agent.
13. The method of claim 9 , wherein the porosity agent is polyethylene glycol.
14. The method of claim 13 , wherein the polyethylene glycol is present in the sol-gel composition in an amount comprising at least about 10 wt % of the total weight of the sol-gel composition.
15. The method of claim 14 , wherein the polyethylene glycol is present in the sol-gel composition in an amount comprising at least about 20 wt % of the total weight of the sol-gel composition.