Spheroidal aggregates comprising single-wall carbon nanotubes and method for making the same
View Patent ↗A method for separating single-wall carbon nanotubes from an aqueous slurry comprises adding a water-immiscible organic solvent to an aqueous slurry comprising single-wall carbon nanotubes, isolating at least some of the single-wall carbon nanotubes in the solvent, and removing the solvent from the single-wall carbon nanotubes to form dried single-wall carbon nanotubes. A spheroidal aggregate of single-wall carbon nanotubes is formed wherein the aggregate is approximately spherical and has a diameter in a range of about 0.1 and about 5 mm, and wherein the aggregate contains at least about 80 wt % single-wall carbon nanotubes. The spheroidal aggregates of single-wall carbon nanotubes are easily handled in industrial processes and are redispersable to single-wall carbon nanotubes and/or ropes of single-wall carbon nanotubes. This invention can also be applied to multi-wall carbon nanotubes.
1. A method for separating multi-wall carbon nanotubes from an aqueous slurry, comprising:
a) adding a water-immiscible organic solvent to an aqueous slurry comprising multi-wall carbon nanotubes;
b) isolating at least some of the multi-wall carbon nanotubes in the solvent; and
c) removing the solvent from the multi-wall carbon nanotubes to form dried multi-wall carbon nanotubes.
2. The method of claim 1 wherein the isolating forms spheroidal aggregates of multi-wall carbon nanotubes.
3. The method of claim 1 wherein the dried multi-wall carbon nanotubes are in the shape of spheroidal aggregates having diameters in the range of about 0.1 mm and about 5 mm.
4. The method of claim 1 wherein the dried multi-wall carbon nanotubes are in the shape of spheroidal aggregates having diameters in the range of about 0.5 mm and about 2 mm.
5. The method of claim 1 wherein the dried multi-wall carbon nanotubes are in the shape of spheroidal aggregates wherein the spheroidal aggregates comprise at least about 80 wt % multi-wall carbon nanotubes.
6. The method of claim 1 wherein the dried multi-wall carbon nanotubes are in the shape of spheroidal aggregates wherein the spheroidal aggregates comprise at least about 90 wt % multi-wall carbon nanotubes.
7. The method of claim 1 wherein the dried multi-wall carbon nanotubes are in the shape of spheroidal aggregates wherein the spheroidal aggregates comprise at least about 95 wt % multi-wall carbon nanotubes.
8. The method of claim 1 wherein the removing step is done by a procedure selected from the group consisting of evaporation, vacuum drying, convective drying and combinations thereof.
9. The method of claim 1 wherein the organic solvent comprises a solvent selected from the group consisting of hydrocarbons, oxygenated hydrocarbons, aliphatic solvents, aromatic solvents, alkanes, alkenes, alkynes, chlorinated hydrocarbons, chlorinated solvents, silicone oils, hydrocarbon oils, and combinations thereof.
10. The method of claim 1 wherein the organic solvent comprises hexane.
11. The method of claim 1 wherein the organic solvent comprises octane.
12. The method of claim 1 wherein the nanotubes and the solvent are present in a ratio from about 1 g nanotubes to about 0.1 ml solvent to about 1 g nanotubes to about 100 mls solvent.
13. The method of claim 1 wherein the nanotubes and the solvent are present in a ratio from about 1 g nanotubes to about 1 ml solvent to about 1 g nanotubes to about 25 mls solvent.
14. A method for forming spheroidal aggregates of multi-wall carbon nanotubes comprising:
a) adding a water-immiscible organic solvent to an aqueous slurry comprising multi-wall carbon nanotubes;
b) forming aggregates of multi-wall carbon nanotubes in the solvent; and
c) removing the solvent from the aggregates to form dried spheroidal aggregates of multi-wall carbon nanotubes.
15. The method of claim 14 wherein the dried spheroidal aggregates have a diameter in the range of about 0.1 mm and about 5 mm.
16. The method of claim 14 wherein the dried spheroidal aggregates have a diameter in the range of about 0.5 mm and about 2 mm.
17. The method of claim 14 wherein the solvent is removed by a procedure selected from the group consisting of evaporation, vacuum drying, convective drying and combinations thereof.
18. The method of claim 14 wherein the dried spheroidal aggregates contain at least about 80 wt % multi-wall carbon nanotubes.
19. The method of claim 14 wherein the dried spheroidal aggregates contain at least about 90 wt % multi-wall carbon nanotubes.
20. The method of claim 14 wherein the dried spheroidal aggregates contain at least about 95 wt % multi-wall carbon nanotubes.
21. The method of claim 14 wherein the organic solvent comprises a solvent selected from the group consisting of hydrocarbons, oxygenated hydrocarbons, aliphatic solvents, aromatic solvents, alkanes, alkenes, alkynes, chlorinated hydrocarbons, chlorinated solvents, silicone oils, hydrocarbon oils, and combinations thereof.
22. The method of claim 14 wherein the organic solvent comprises hexane.
23. The method of claim 14 wherein the organic solvent comprises octane.
24. The method of claim 14 wherein the nanotubes and the solvent are present in a ratio from about 1 g nanotubes to about 0.1 ml solvent to about 1 g nanotubes to about 100 mls solvent.
25. The method of claim 14 wherein the nanotubes and the solvent are present in a ratio from about 1 g nanotubes to about 1 ml solvent to about 1 g nanotubes to about 25 mls solvent.
26. An aggregate comprising multi-wall carbon nanotubes wherein the aggregate is spheroidal and has a diameter in a range of about 0.1 mm and about 5 mm, and wherein the aggregate contains at least about 80 wt % multi-wall carbon nanotubes.
27. The aggregate of claim 26 wherein the diameter is in the range of about 0.5 mm and about 2 mm.
28. The aggregate of claim 26 wherein the aggregate contains at least about 90 wt % multi-wall carbon nanotubes.
29. The aggregate of claim 26 wherein the aggregate contains at least about 95 wt % multi-wall carbon nanotubes.