Polymer / carbon-nanotube interpenetrating networks and process for making same
The present invention is directed to new methods for combining, processing, and modifying existing materials, resulting in novel products with enhanced mechanical, electrical and electronic properties. The present invention provides for polymer/carbon nanotube composites with increased strength and toughness; beneficial for lighter and/or stronger structural components for terrestrial and aerospace applications, electrically and thermally conductive polymer composites, and electrostatic dissipative materials. Such composites rely on a molecular interpenetration between entangled single-wall carbon nanotubes (SWNTs) and cross-linked polymers to a degree not possible with previous processes.
1. A method comprising the steps of:
a) introducing CNTs and prepolymer molecules into a solvent to form a solvent mixture, wherein the solvent mutually:
i) dissolves the prepolymer molecules; and
ii) achieves molecular penetration into bundles of CNTs causing them to at least partially expand; and
b) atomizing the solvent mixture into micro-droplets via spraying;
c) rapidly removing the solvent from the micro-droplets and, simultaneously, at least partially curing the prepolymer to provide solid polymer/CNT particles; and
d) depositing the solid polymer/CNT particles on a surface, causing the solid polymer/CNT particles to agglomerate while completing their cure, to form a polymer/CNT composite of desired size and shape.
2. The method of claim 1 , wherein the CNTs are SWNTs.
3. The method of claim 1 , wherein the CNTs are functionalized.
4. The method of claim 1 , wherein the prepolymer is selected from the group consisting of epoxy resins, unsaturated polyester resins, vinyl ester resins, and combinations thereof.
5. The method of claim 1 , wherein the at least partially curing of the prepolymer comprises at least one curing agent.
6. The method of claim 5 , wherein the at least one curing agent is selected from the group consisting of di-amines, poly-amines, imidazoles, and combinations thereof.
7. The method of claim 1 , wherein the step of introducing involves a technique selected from the group consisting of sonication, mechanical shear, heating, and combinations thereof.
8. The method of claim 1 , wherein the step of rapidly removing solvent comprises exposure to a condition selected from the group consisting of heating, mechanical pumping, evacuation, and combinations thereof.
9. The method of claim 1 further comprising a second curing step to fully cure the prepolymer.
10. The method of claim 1 , wherein the step of depositing the particles is done in combination with a curing method, said curing method selected from the group consisting of thermal curing, radiative curing, microwave curing, and combinations thereof, to effect crosslinking.
11. The method of claim 1 , wherein the solid polymer/CNT particles are deposited on a rotating surface.
12. The method of claim 1 , wherein the solid polymer/CNT particles have a size that ranges from about 1 micron to about 100 microns.
13. The method of claim 1 , wherein the solvent mixture, comprising CNTs, prepolymer, and solvent, is formed immediately prior to being spayed through a nozzle.
14. The method of claim 1 , further comprising multiple spray guns for atomizing the solvent mixture, wherein each spray gun sprays a different mixture.
15. The method of claim 1 , wherein the CNTs in the polymer/CNT composite are aligned.