Anisotropic nanotube fabric layers and films and methods of forming same
View Patent ↗Methods for forming anisotropic nanotube fabrics are disclosed. In one aspect, a nanotube application solution is rendered into a nematic state prior to its application over a substrate. In another aspect, a pump and narrow nozzle assembly are employed to realize a flow induced alignment of a plurality of individual nanotube elements as they are deposited onto a substrate element. In another aspect, nanotube adhesion promoter materials are used to form a patterned nanotube application layer, providing narrow channels over which nanotube elements will self align during an application process. Specific dip coating processes which are well suited for aiding in the creation of anisotropic nanotube fabrics are also disclosed.
1. A method of forming an anisotropic nanotube fabric layer onto a substrate element, which comprises:
suspending a first plurality of nanotube elements within a solvent to form a nanotube application solution;
rendering said nanotube application solution into a nematic state by adjusting the concentration level of said nanotube application solution; and
applying said rendered nanotube application solution over said substrate element.
2. The method of claim 1 , wherein said first plurality of nanotube elements are carbon nanotubes.
3. The method of claim 1 , wherein the step of rendering is achieved by increasing the concentration of said nanotube elements within said nanotube application solution.
4. The method of claim 3 , wherein the concentration of said nanotube elements within said nanotube application solution is increased by adding a second plurality of nanotube elements to said solvent.
5. The method of claim 3 , wherein the concentration of said nanotube elements within said nanotube application solution is increased by removing a volume of said solvent.
6. The method of claim 3 , wherein the step of rendering is achieved by increasing the concentration of said nanotube elements from a first value below about 0.005 g/ml to a second value above about 0.05 g/ml.
7. The method of claim 1 , wherein the step of applying is selected from the group consisting of a spin coating operation, a dip coating operation and a spray coating operation.
8. The method of claim 1 , wherein the substrate is flexible.