ULTRA-LOW REFRACTIVE INDEX HIGH SURFACE AREA NANOPARTICULATE FILMS AND NANOPARTICLES

• US 20090269016A1
• Filed: 02/17/2009
• Published: 10/29/2009
• Est. Priority Date: 02/14/2008
• Status: Active Grant

• Current Assignee: Curators of the University of Missouri (University of Missouri)
• Original Assignee: Curators of the University of Missouri (University of Missouri)
• Inventors: Gangopadhyay, Keshab, Polo-Parada, Luis, Gangopadhyay, Shubhra, Bok, Sangho, Korampally, Venumadhav
• Granted Patent: US 7,907,809 B2
• Time in Patent Office: Days
• US Class Current: 385/129
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C01B 33/12 Silica; Hydrates thereof, e.g. lepidoic silicic acid
• CPC Class Codes: C01B 33/14 Colloidal silica, e.g. dispersions, gels, sols
• CPC Class Codes: C01B 33/145 Preparation of hydroorganosols, organosols or dispersions in an organic medium
• CPC Class Codes: C08G 77/045 containing less than 25 silicon atoms
• CPC Class Codes: C08G 77/06 Preparatory processes C08G77/045 takes precedence
• CPC Class Codes: C08L 2666/28 Non-macromolecular organic substances
• CPC Class Codes: C08L 83/04 Polysiloxanes
• CPC Class Codes: G02B 2006/0325 Fluid core or cladding
• CPC Class Codes: G02B 6/0229 characterised by nanostructures, i.e. structures of size less than 100 nm, e.g. quantum dots
• CPC Class Codes: G02B 6/122 Basic optical elements, e.g. light-guiding paths
• CPC Class Codes: Y10S 977/778 within specified host or matrix material, e.g. nanocomposite films
• CPC Class Codes: Y10S 977/78 Possessing fully enclosed nanosized voids or physical holes
• CPC Class Codes: Y10T 428/249986 Void-containing component contains also a solid fiber or solid particle

Abstract

Nanoparticles having a mean particle size of less than about 25 nanometers and a mean pore size of less than 10 nanometers, and a mean surface area of at least 500 m²/g; nanoporous films of such nanoparticles; and composites and devices containing such nanoparticles and nanoporous films.

Claims

1. A nanoporous film comprising:

organosilica nanoparticles having a mean particle size of less than about 25 nanometers and a mean pore size of less than 10 nanometers;

wherein the film has a surface area of at least 500 m²/g and a porosity of at least about 50% by volume.

2. The nanoporous film of claim 1 wherein the film has a dielectric constant of less than 2.

3. The nanoporous film of claim 1 wherein the film has a refractive index of less than 1.33.

4. The nanoporous film of claim 1 wherein the film has a thickness of less than 3 microns.

5. The nanoporous film of claim 1 wherein the film has a thickness of less than 1 micron.

6. The nanoporous film of claim 1 wherein:

the film has a thickness of less than about 3 microns;

the film has a dielectric constant of less than 2;

said surface area of the film is at least about 600 m²/g; and

the film has a refractive index of less than 1.33.

7. The nanoporous film of claim 1 wherein:

the film has a thickness of less than about 3 microns;

the film has a dielectric constant of less than 1.8;

said surface area of the film is at least about 600 m²/g; and

the film has a refractive index of less than 1.2.

8. The nanoporous film of claim 1 wherein:

the film has a thickness of less than about 3 microns;

the film has a dielectric constant of less than 1.5;

said surface area of the film is at least about 1200 m²/g; and

the film has a refractive index of less than 1.15.

9. The film of claim 1 wherein the nanoparticles comprise polymethylsilsesquioxane nanoparticles.

10. The nanoporous film of claim 1 wherein:

the nanoparticles comprise polymethylsilsesquioxane nanoparticles;

the film has a thickness of less than about 3 microns;

the film has a dielectric constant of less than 2;

said surface area of the film is at least about 600 m²/g; and

the film has a refractive index of less than 1.33.

11. The nanoporous film of claim 1 wherein:

the nanoparticles comprise polymethylsilsesquioxane nanoparticles;

the film has a thickness of less than about 3 microns;

the film has a dielectric constant of less than 1.8;

said surface area of the film is at least about 600 m²/g; and

the film has a refractive index of less than 1.2.

12. The nanoporous film of claim 1 wherein:

the nanoparticles comprise polymethylsilsesquioxane nanoparticles;

the film has a thickness of less than about 3 microns;

the film has a dielectric constant of less than 1.5;

said surface area of the film is at least about 1200 m²/g; and

the film has a refractive index of less than 1.15.

organosilica nanoparticles having a mean particle size of less than about 25 nanometers and a mean pore size of less than 10 nanometers;

wherein the film has a surface area of at least 500 m²/g and a porosity of at least about 50% by volume.

13. A composite comprising:

a substrate;

a nanoporous film on the substrate, the nanoporous film comprising organosilica nanoparticles having a mean particle size of less than about 25 nanometers and a mean pore size of less than 10 nanometers;

wherein the film has a surface area of at least 500 m²/g and a porosity of at least about 50% by volume.

14. The composite of claim 13 wherein:

the nanoparticles comprise polymethylsilsesquioxane nanoparticles;

the film has a thickness of less than about 3 microns;

the film has a dielectric constant of less than 1.8;

said surface area of the film is at least about 1200 m²/g; and

the film has a refractive index of less than 1.2.

15. The composite of claim 13 wherein the substrate is an optical fiber.

16. The composite of claim 13 wherein the substrate is a waveguide surface.

17. The composite of claim 13 wherein the substrate is a component of a chemical or biological sensor.

18. The composite of claim 13 wherein the substrate is a component of a chemical or biological sensor and the nanoparticles comprise gold.

19. The composite of claim 13 wherein the nanoparticles further comprise a dye.

20. The composite of claim 13 wherein the film further comprises biological molecules linked to the nanoparticles.

21. A process for the preparation of a nanoporous film comprising nanoparticles, the process comprising:

forming a solution of a nanoparticle precursor in a mixed solvent system comprising a first solvent and a second solvent, wherein the first solvent is different from the second solvent, wherein the second solvent has a boiling point which is greater than a boiling point of the first solvent, and wherein the nanoparticle precursor has a greater solubility in the first solvent than in the second solvent;

removing at least 50% of the first solvent;

depositing the solution as a film onto a substrate; and

calcining the deposited film at a temperature of at least 200°

C. to remove the second solvent from the film to form a nanoporous, nanoparticulate film having a thickness of less than 3 microns, a surface area of at least 500 m²/g, a refractive index of less than 1.33, a dielectric constant of less than 2, and a porosity of at least about 50% by volume.

22. The process of claim 21 wherein the nanoparticles are organosilicate nanoparticles.

23. The process of claim 21 wherein the nanoparticle precursor comprises polymethylsilsesquioxane.

24. The process of claim 21 wherein:

the nanoparticle precursor comprises polymethylsilsesquioxane;

the first solvent comprises propylene glycol methyl ether acetate;

the second solvent comprises poly(propylene glycol); and

the calcining is at a temperature of at least 400°

C.

25. The process of claim 21 comprising an additional step of incorporating a labile polymer porogen into the solution after said removing first solvent, and wherein said labile polymer porogen is removed from the deposited film during the calcining.

26. A nanoparticulate mass comprising:

organosilicate nanoporous nanoparticles having a mean particle size of less than about 25 nanometers, a mean pore size of less than 10 nanometers, and a mean surface area of at least 500 m²/g.

27. The nanoparticulate mass of claim 26 wherein said mean surface area is at least about 1000 m²/g.

28. The nanoparticulate mass of claim 26 wherein the nanoparticles comprise polymethylsilsesquioxane nanoparticles.

29. The mass of claim 26 further comprising a dye.

30. The mass of claim 26 wherein biological molecules are linked to the nanoparticles.

31. A waveguide comprising:

at least two spaced-apart opposed surfaces defining a channel therebetween;

a waveguide inlet; and

a film on each of the two spaced-apart opposed surfaces wherein the film comprises organosilica nanoparticles having a mean particle size of less than about 25 nanometers and a mean pore size of less than 10 nanometers;

wherein the film has a surface area of at least 500 m²/g and a porosity of at least about 50% by volume;

the film has a thickness of less than about 3 microns;

the film has a dielectric constant of less than 2; and

the film has a refractive index of less than 1.33.

32. The waveguide of claim 31 wherein the nanoparticles comprise polymethylsilsesquioxane nanoparticles.