Claims
- 1. A method comprising:starting exposure of a photocatalytic coating layer on a substrate to photoexcitation, said layer including a photocatalyst; and stopping said exposure when said photoexcitation yields a mosaic of hydrophilic and hydrophobic regions in the exposed area.
- 2. The method of claim 1 wherein each of said hydrophilic and hydrophobic regions have an area of about 100 to 10,000 nm2.
- 3. The method of claim 1 wherein, after said stopping step, the surface of said layer is amphiphilic such that oil deposited on said surface can be easily removed by rinsing said surface with water and water deposited on said surface can be easily removed by rinsing with oil.
- 4. The method of claim 1 wherein said hydrophobic regions are more hydrophobic after said stopping of said exposure than before said starting of said exposure.
- 5. The method of claim 1 wherein the total area of said hydrophilic regions is at least about 20% but less than 100% of said exposed area.
- 6. The method of claim 1 wherein, after said stopping step, the surface of said layer has a contact angle with water of not more than 5° and a contact angle with glyceride trioleate of not more than 5°.
- 7. The method of claim 1 wherein the photoexcitation is carried out by exposing the layer to sunlight or UV light having an intensity within the range from 0.001 to 1 mW/cm2.
- 8. The method of claim 1 wherein said photocatalyst comprises a metal oxide, and oxygen atoms of said metal oxide are exposed on the surface of said layer, and substantially all of said exposed oxygen atoms are oxygen atoms at bridging sites in the metal oxide.
- 9. The method of claim 8 wherein the metal oxide is rutile titanium oxide with the (110) crystal face or (100) crystal face thereof being exposed on the surface of the layer containing a photocatalyst.
- 10. The method of claim 8 wherein the metal oxide is anatase titanium oxide with the (001) crystal face thereof being exposed on the surface of the layer containing a photocatalyst.
- 11. The method of claim 1 further comprising the step of subjecting the layer to water.
- 12. The method of claim 11 wherein the water is in the form of humidity.
- 13. The method of claim 1 wherein said hydrophilic regions have hydroxyl groups fixed thereto, with water molecules physically adsorbed to said hydroxyl groups.
- 14. A method of increasing hydrophobicity of a hydrophobic region on a photocatalytic coating layer, the method comprising:starting exposure of the region to photoexcitation; and stopping said exposure when said photoexcitation renders the exposed region more hydrophobic than before the starting of said photoexcitation.
- 15. The method of claim 14 wherein the increase in hydrophobicity is characterized by a contact angle of the layer with glyceride trioleate being not more than 5°.
- 16. The method of claim 14 wherein said hydrophobic region has an area of about 100 to 10,000 nm2.
Priority Claims (2)
Number |
Date |
Country |
Kind |
8-344584 |
Dec 1996 |
JP |
|
9-256090 |
Sep 1997 |
JP |
|
Parent Case Info
This application is a continuation of application Ser. No. 08/987,670, filed Dec. 9, 1997, now U.S. Pat. No. 5,939,194, which is a continuation-in-part of application Ser. No. 08/933,886, filed Sep. 19, 1997, now U.S. Pat. No. 6,013,372, which is a continuation-in-part of PCT Application No. JP96/00733, filed Mar. 21, 1996, and which designated the U.S.
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Continuations (1)
|
Number |
Date |
Country |
Parent |
08/987670 |
Dec 1997 |
US |
Child |
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|
US |
Continuation in Parts (2)
|
Number |
Date |
Country |
Parent |
08/933886 |
Sep 1997 |
US |
Child |
08/987670 |
|
US |
Parent |
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Mar 1996 |
US |
Child |
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|
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