Fibers of aligned single-wall carbon nanotubes and process for making the same
View Patent ↗The present invention involves fibers of highly aligned single-wall carbon nanotubes and a process for making the same. The present invention provides a method for effectively dispersing single-wall carbon nanotubes. The process for dispersing the single-wall carbon nanotubes comprises mixing single-wall carbon nanotubes with 100% sulfuric acid or a superacid, heating and stirring under an inert, oxygen-free environment. The single-wall carbon nanotube/acid mixture is wet spun into a coagulant to form the single-wall carbon nanotube fibers. The fibers are recovered, washed and dried. The single-wall carbon nanotubes were highly aligned in the fibers, as determined by Raman spectroscopy analysis.
1. A method of making a fiber of aligned single-wall carbon nanotubes, comprising:
(a) mixing single-wall carbon nanotubes with a superacid selected from the group consisting of:
(i) a Brønsted superacid selected from the group consisting of perchloric acid, chlorosulfuric acid, fluorosulfuric acid, chlorosulfonic acid, fluorosulfonic acid, perfluoroalkanesulfonic acid, trifluoromethanesulfonic acid, higher perfluoroalkanesulfonic acid, C 2 F 5 SO 3 H, C 4 F 9 SO 3 H, C 5 F 11 SO 3 H, C 6 F 13 SO 3 H, C 8 F 17 SO 3 H,
and α, ω-perfluoroalkanedisulfonic acid,
(ii) a Lewis superacid selected from the group consisting of antimony pentafluoride, arsenic pentafluoride, tantalum pentafluoride and niobium pentafluoride, and
(iii) a Brønsted-Lewis conjugate superacid selected from the group consisting of polyphosphoric acid-oleum mixtures, tetra(hydrogen sulfato)boric acid-sulfuric acid, fluorosulfuric acid-antimony pentafluoride, fluorosulfuric acid-sulfur trioxide, fluorosulfuric acid-arsenic pentafluoride, HSO 3 F:HF:SbF 5 , HSO 3 F:SbF 5 :SO 3 , a perfluoroalkanesulfonic acid-based system, C n F 2n+1 SO 3 H:SbF 5 , where n=1, 2 or 4, CF 3 SO 3 H:B(SO 3 CF 3 ) 3 , hydrogen-flouride-antimony pentafluoride, hydrogen fluoride-tantalum pentafluoride, hydrogen fluoride-boron trifluoride, a cojugate Friedel-Crafts acid, HBr:AlBr 3 , and HCl:AlCl 3 ; to form a single-wall carbon nanotube/acid mixture, and
(b) spinning the single-wall carbon nanotube/acid mixture to form a fiber.
2. The method of claim 1 , wherein the single-wall carbon nanotubes are at a concentration range between about 0.01 wt % and about 10 wt % in the acid.
3. The method of claim 1 , wherein the single-wall carbon nanotubes are at a concentration range between about 4 wt % and about 10 wt % in the acid.
4. The method of claim 1 , wherein the single-wall carbon nanotubes are at a concentration range between about 6 wt % and about 8 wt % in the acid.
5. The method of claim 1 , wherein the mixing step is done in a time range between about 3 hours and about 3 days.
6. The method of claim 1 , wherein the spinning step comprises wet spinning into a coagulant.
7. The method of claim 1 , wherein the aligned single-wall carbon nanotubes in the fiber have a Fraser fraction of at least about 0.25.
8. The method of claim 1 , wherein the aligned single-wall carbon nanotubes in the fiber have a Fraser fraction of at least about 0.5.
9. The method of claim 1 , wherein the aligned single-wall carbon nanotubes in the fiber have a Fraser fraction of at least about 0.7.
10. The method of claim 1 , further comprising washing the fiber.
11. The method of claim 10 , wherein the washing is done in a liquid selected from the group consisting of water, diethyl ether, methanol and combinations thereof.
12. The method of claim 1 , further comprising drying the fiber.
13. The method of claim 12 , wherein the drying is done by a method selected from the group consisting of heating, air drying, vacuum drying and a combination thereof.
14. The method of claim 1 , wherein the mixing step is done under an inert atmosphere.
15. The method of claim 1 , wherein the mixing step is done at a temperature range between about room temperature and about 150° C.
16. The method of claim 6 , wherein the coagulant is selected from the group consisting of water, diethyl ether, 10% sulfuric acid, ethylene glycol and mixtures thereof.
17. The method of claim 1 , wherein the superacid is trifluoromethanesulfonic acid.
18. The method of claim 1 , further comprising annealing the fiber.
19. The method of claim 18 , wherein the annealing is done at a temperature in the range between about 400° C. and about 800° C.
20. The method of claim 1 further comprising subjecting the fiber to a reducing environment at an elevated temperature.
21. The method of claim 20 , wherein the temperature is up to about 450° C.
22. A method of making a fiber of aligned single-wall carbon nanotubes, comprising:
(a) mixing single-wall carbon nanotubes with an anhydrous acid selected from the group consisting of 100% sulfuric acid and a superacid to form a single-wall carbon nanotube/acid mixture, wherein the superacid is trifluoromethanesulfonic acid, and
(b) spinning the single-wall carbon nanotube/acid mixture to form a fiber.
23. A method of making a fiber of aligned single-wall carbon nanotubes, comprising:
(a) mixing single-wall carbon nanotubes with an anhydrous acid selected from the group consisting of 100% sulfuric acid and a superacid to form a single-wall carbon nanotube/acid mixture, and
(b) spinning the single-wall carbon nanotube/acid mixture to form a fiber, wherein the spinning step comprises wet spinning into a coagulant and wherein the coagulant is selected from the group consisting of water, diethyl ether, 10% sulfuric acid, ethylene glycol and mixtures thereof.
24. A method of making a fiber of aligned single-wall carbon nanotubes, comprising:
(a) mixing single-wall carbon nanotubes with an anhydrous acid selected from the group consisting of 100% sulfuric acid and a superacid to form a single-wall carbon nanotube/acid mixture, and
(b) spinning the single-wall carbon nanotube/acid mixture to form a fiber, and
(c) annealing the fiber.
25. The method of claim 24 , wherein the annealing is done at a temperature in the range between about 400° C. and about 800° C.
26. A method of making a fiber of aligned single-wall carbon nanotubes, comprising:
(a) mixing single-wall carbon nanotubes with an anhydrous acid selected from the group consisting of 100% sulfuric acid and a superacid to form a single-wall carbon nanotube/acid mixture,
(b) spinning the single-wall carbon nanotube/acid mixture to form a fiber, and
(c) subjecting the fiber to a reducing environment at an elevated temperature.
27. The method of claim 26 , wherein the temperature is up to about 450° C.
28. A method for forming intercalated single-wall carbon nanotubes, comprising:
mixing single-wall carbon nanotubes with a superacid selected from the group consisting of
(a) a Brønsted superacid selected from the group consisting of perchloric acid, chlorosulfuric acid, fluorosulfuric acid, chlorosulfonic acid, fluorosulfonic acid, perfluoroalkanesulfonic acid, trifluoromethanesulfonic acid, higher perfluoroalkanesulfonic acid, C 2 F 5 SO 3 H, C 4 F 9 SO 3 H, C 5 F 11 SO 3 H, C 6 F 13 SO 3 H, C 8 F 17 SO 3 H,
and α, ω-perfluoroalkanedisulfonic acid,
(b) a Lewis superacid selected from the group consisting of antimony pentafluoride, arsenic pentafluoride, tantalum pentafluoride and niobium pentafluoride, and
(c) a Brønsted-Lewis conjugate superacid selected from the group consisting of polyphosphoric acid-oleum mixtures, tetra(hydrogen sulfato)boric acid-sulfuric acid, fluorosulfuric acid-antimony pentafluoride, fluorosulfuric acid-sulfur trioxide, fluorosulfuric acid-arsenic pentafluoride, HSO 3 F:HF:SbF 5 , HSO 3 F:SbF 5 :SO 3 , a perfluoroalkanesulfonic acid-based system, C n F 2n+1 SO 3 H:SbF 5 , where n=1, 2 or 4, CF 3 SO 3 H:B(SO 3 CF 3 ) 3 , hydrogen-fluoride-antimony pentafluoride, hydrogen fluoride-tantalum pentafluoride, hydrogen fluoride-boron trifluoride, a conjugate Friedel-Crafts acid, HBr:AlBr 3 , and HCl:AlCl 3 ; under an inert atmosphere at a temperature ranging from about room temperature to about 150° C. for a time sufficient to form a single-wall carbon nanotube/acid mixture.
29. The method of claim 28 , wherein the single-wall carbon nanotubes are at a concentration range between about 0.01 wt % and about 10 wt % in the acid.
30. The method of claim 28 , wherein the superacid is an aggregate redispersing acid.
31. The method of claim 28 , wherein the intercalated single-wall carbon nanotubes form super ropes.
32. The method of claim 28 , wherein the superacid is an aggregate redispersible acid.
33. The method of claim 28 , wherein the intercalated single-wall carbon nanotubes form super ropes.
34. The method of claim 33 , wherein the super ropes have a diameter in the range between about one-half micron and about 2 microns.