Controlled-orientation films and nanocomposites including nanotubes or other nanostructures
Generally, the present invention provides methods for the production of materials comprising a plurality of nanostructures such as nanotubes (e.g., carbon nanotubes) and related articles. The plurality of nanostructures may be provided such that their long axes are substantially aligned and, in some cases, continuous from end to end of the sample. For example, in some cases, the nanostructures may be fabricated by uniformly growing the nanostructures on the surface of a substrate, such that the long axes are aligned and non-parallel to the substrate surface. The nanostructures may be, in some instances, substantially perpendicular to the substrate surface. In one set of embodiments, a force with a component normal to the long axes of the nanostructures may be applied to the substantially aligned nanostructures. The application of a force may result in a material comprising a relatively high volume fraction or mass density of nanostructures. In some instances, the application of a force may result in a material comprising relatively closely-spaced nanostructures. The materials described herein may be further processed for use in various applications, such as composite materials (e.g., nanocomposites). For example, a set of aligned nanostructures may be formed, and, after the application of a force, transferred, either in bulk or to another surface, and combined with another material (e.g., to form a nanocomposite) to enhance the properties of the material.
1. An article comprising a plurality of elongated nanostructures wherein:
the long axes of the elongated nanostructures are substantially aligned relative to each other;
each elongated nanostructure is positioned relative to an adjacent elongated nanostructure at a distance so as to together define an average distance between adjacent elongated nanostructures;
the plurality of elongated nanostructures extends a distance at least 10 times greater than the average distance between adjacent elongated nanostructures in each of two orthogonal directions each perpendicular to the long axes; and
the volume fraction of the elongated nanostructures within the article is at least about 5%.
2. The article of claim 1 , wherein the elongated nanostructures comprise carbon-based nanostructures.
3. The article of claim 2 , wherein the carbon-based elongated nanostructures comprise carbon nanotubes.
4. The article of claim 1 , further comprising a solid support material between the elongated nanostructures.
5. The article of claim 4 , wherein the support material comprises a monomer.
6. The article of claim 4 , wherein the support material comprises a polymer.
7. The article of claim 4 , wherein the support material comprises a fiber.
8. The article of claim 4 , wherein the support material comprises a ceramic.
9. The article of claim 4 , wherein the support material comprises a metal.
10. The article of claim 1 , wherein the average distance between the elongated nanostructures is less than about 80 nm.
11. The article of claim 1 , wherein the volume fraction of the elongated nanostructures within the article is at least about 10%.
12. The article of claim 1 , wherein the volume fraction of the elongated nanostructures within the article is at least about 20%.
13. The article of claim 1 , wherein the volume fraction of the elongated nanostructures within the article is at least about 40%.
14. The article of claim 1 , wherein the volume fraction of the elongated nanostructures within the article is at least about 60%.
15. The article of claim 1 , wherein the volume fraction of the elongated nanostructures within the article is at least about 70%.
16. The article of claim 1 , wherein the volume fraction of the elongated nanostructures within the article is at least about 75%.
17. The article of claim 1 , wherein the volume fraction of the elongated nanostructures within the article is at least about 78%.
18. The article of claim 1 , wherein the elongated nanostructures comprise nanotubes.
19. The article of claim 1 , wherein the elongated nanostructures comprise nanofibers.
20. The article of claim 1 , wherein the elongated nanostructures comprise nanowires.
21. The article of claim 1 , wherein the plurality of elongated nanostructures extends a distance at least 100 times greater than the average distance between adjacent elongated nanostructures in each of two orthogonal directions each perpendicular to the long axes.
22. The article of claim 1 , wherein the plurality of elongated nanostructures extends a distance at least 1000 times greater than the average distance between adjacent elongated nanostructures in each of two orthogonal directions each perpendicular to the long axes.
23. The article of claim 1 , wherein the elongated nanostructures have an average diameter of 75 nm or less.
24. The article of claim 1 , wherein the elongated nanostructures have an average diameter of 50 nm or less.
25. The article of claim 1 , wherein the elongated nanostructures have an average diameter of 25 nm or less.
26. The article of claim 1 , wherein the elongated nanostructures have an average diameter of 10 nm or less.
27. The article of claim 1 , wherein the average distance between the elongated nanostructures is less than about 60 nm.
28. The article of claim 1 , wherein the average distance between the elongated nanostructures is less than about 40 nm.
29. The article of claim 1 , wherein the average distance between the elongated nanostructures is less than about 30 nm.
30. The article of claim 1 , wherein the average distance between the elongated nanostructures is less than about 20 nm.
31. The article of claim 1 , wherein the average distance between the elongated nanostructures is less than about 10 nm.
32. The article of claim 1 , wherein the average distance between the elongated nanostructures is less than about 5 nm.