Ultra-low refractive index high surface area nanoparticulate films and nanoparticles

1. A nanoporous film comprising:

organosilica nanoparticles having a particle size from about 2 to about 5 nm and 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 m 2 /g and a porosity of at least about 50% by volume.

2. 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 m 2 /g, a porosity of at least about 50% by volume, and a dielectric constant of less than 2.

3. The nanoporous film of claim 2 wherein the film has a refractive index of less than 1.33.

4. The nanoporous film of claim 2 wherein the film has a thickness of less than 3 microns.

5. The nanoporous film of claim 2 wherein the film has a thickness of less than 1 micron.

6. The nanoporous film of claim 2 wherein:

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

said surface area of the film is at least about 600 m 2 /g; and

the film has a refractive index of less than 1.33.

7. The nanoporous film of claim 2 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 m 2 /g; and

the film has a refractive index of less than 1.2.

8. The nanoporous film of claim 2 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 m 2 /g; and

the film has a refractive index of less than 1.15.

9. The nanoporous film of claim 2 wherein the nanoparticles comprise polymethylsilsesquioxane nanoparticles.

10. The nanoporous film of claim 2 wherein:

the nanoparticles comprise polymethylsilsesquioxane nanoparticles;

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

said surface area of the film is at least about 600 m 2 /g; and

the film has a refractive index of less than 1.33.

11. The nanoporous film of claim 2 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 m 2 /g; and

the film has a refractive index of less than 1.2.

12. The nanoporous film of claim 2 wherein:

the nanoparticles comprise polymethylsilsesquioxane nanoparticles, have a mean particle size of less than about 25 nanometers and have a mean pore size of less than 10 nanometers;

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 m 2 /g;

the film has a refractive index of less than 1.15; and

the film has a surface area of at least 500 m 2 /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 particle size from about 2 to about 5 nm and 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 m 2 /g and a porosity of at least about 50% by volume.

14. 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, 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;

the film has a surface area of at least about 1200 m 2 /g; and

the film has a refractive index of less than 1.2.

15. The composite of claim 14 wherein the substrate is an optical fiber.

16. 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, 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;

the film has a surface area of at least about 1200 m 2 /g; and

the film has a refractive index of less than 1.2;

wherein the substrate is a waveguide surface.

17. The composite of claim 14 wherein the substrate is a component of a chemical or biological sensor.

18. The composite of claim 14 wherein the substrate is a component of a chemical or biological sensor and the nanoparticles comprise gold.

19. The composite of claim 14 wherein the nanoparticles further comprise a dye.

20. The composite of claim 14 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 m 2 /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 particle size from about 2 to about 5 nm and 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 m 2 /g.

27. 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 about 1000 m 2 /g.

28. A nanoparticulate mass comprising:

organosilicate nanoporous nanoparticles comprising polymethylsilsesquioxane 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 m 2 /g.

29. The mass of claim 27 further comprising a dye.

30. The mass of claim 27 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 m 2 /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.

33. The process of claim 21 wherein the nanoporous, nanoparticulate film contains nanoparticles having a mean particle size of less than about 25 nanometers.

34. The process of claim 21 wherein the nanoporous, nanoparticulate film contains nanoparticles having a particle size of from about 2 to about 5 nanometers.

35. The nanoporous film of claim 2 comprising organosilica nanoparticles having a particle size of from about 2 to about 5 nanometers.

36. The composite of claim 14 comprising organosilica nanoparticles having a particle size from about 2 to about 5 nanometers.

37. The nanoparticulate mass of claim 27 comprising organosilica nanoparticles having a particle size from about 2 to about 5 nanometers.