Methods For Sorting Nanotubes By Wall Number

Abstract

The present teachings provide methods for sorting nanotubes according to their wall number, and optionally further in terms of their diameter, electronic type, and/or chirality. Also provided are highly enriched nanotube populations provided thereby and articles of manufacture including such populations.

1 . A method of separating carbon nanotubes by wall number, the method comprising:
 centrifuging a carbon nanotube composition in contact with a first fluid medium comprising a first density gradient; and   separating the carbon nanotube composition into two or more separation fractions, wherein
 the carbon nanotube composition comprises one or more surface active components and a carbon nanotube population comprising double-walled carbon nanotubes and carbon nanotubes having a wall number other than two, and 
 at least one of the two or more separation fractions comprises a carbon nanotube subpopulation comprising a higher percentage of double-walled carbon nanotubes than the carbon nanotube population. 
   
     
     
         2 . The method of  claim 1 , wherein the two or more separation fractions are visibly distinguishable by the human eye. 
     
     
         3 . The method of  claim 1  or  2 , wherein the carbon nanotube population comprises double-walled carbon nanotubes having a mean outer wall diameter of less than about 1.7 nm. 
     
     
         4 . The method of  claim 1 , wherein the carbon nanotube population comprises double-walled carbon nanotubes and single-walled carbon nanotubes having overlapping outer wall diameters. 
     
     
         5 . The method of  claim 4 , wherein at least one of the two or more separation fractions comprises a carbon nanotube subpopulation comprising a higher percentage of single-walled carbon nanotubes than the carbon nanotube population. 
     
     
         6 . The method of  claim 4 , wherein the carbon nanotube composition is introduced into the first fluid medium at a density less than about 1.095 g/mL. 
     
     
         7 . The method of  claim 6 , comprising centrifuging an enriched separation fraction in contact with a second fluid medium comprising a second density gradient, wherein the enriched separation fraction comprises a carbon nanotube subpopulation comprising a higher percentage of double-walled carbon nanotubes than the carbon nanotube population, wherein the enriched separation fraction is introduced into the second fluid medium at a density greater than about 1.115 g/mL. 
     
     
         8 . The method of  claim 1 , wherein the carbon nanotube population comprises multi-walled carbon nanotubes comprising three or more walls. 
     
     
         9 . A carbon nanotube population comprising greater than about 95% double-walled carbon nanotubes. 
     
     
         10 . A method of separating carbon nanotubes by electronic type, the method comprising:
 centrifuging a carbon nanotube composition in contact with a first fluid medium comprising a first density gradient; and   separating the carbon nanotube composition into two or more separation fractions, wherein
 the carbon nanotube composition comprises two or more surface active components and a carbon nanotube population comprising double-walled carbon nanotubes having a semiconducting outer wall (s-DWCNTs), and double-walled carbon nanotubes having a metallic outer wall (m-DWCNTs), and 
 the two or more separation fractions comprise a first separation fraction comprising a carbon nanotube subpopulation comprising a higher percentage of s-DWCNTs than the carbon nanotube population, and a second separation fraction comprising a carbon nanotube subpopulation comprising a higher percentage of m-DWCNTs than the carbon nanotube population. 
   
     
     
         11 . The method of  claim 10 , wherein the two or more surface active components comprise a planar surface active component and a linear surface active component. 
     
     
         12 . The method of  claim 10 , wherein the carbon nanotube population comprises semiconducting single-walled carbon nanotubes (s-SWCNTs) and metallic single-walled carbon nanotubes (m-SWCNTs), and wherein after the centrifuging step, the carbon nanotube composition is separated by wall number and by outer wall electronic type into at least four separation fractions, the at least four separation fractions comprising the first separation fraction, the second separation fraction, a third separation fraction comprising a carbon nanotube subpopulation comprising a higher percentage of s-SWCNTs than the carbon nanotube population, and a fourth separation fraction comprising a carbon nanotube subpopulation comprising a higher percentage of m-SWCNTs than the carbon nanotube population. 
     
     
         13 . The method of  claim 12 , wherein the relative ratio of the two or more surface active components is selected to cause metallic carbon nanotubes to have a lower buoyant density than semiconducting carbon nanotubes regardless of wall number. 
     
     
         14 . The method of  claim 12 , wherein the relative ratio of the two or more surface active components is selected to cause semiconducting carbon nanotubes to have a lower buoyant density than metallic carbon nanotubes of the same wall number. 
     
     
         15 . The method of  claim 12 , where the relative ratio of the two or more surface active components is selected to cause metallic carbon nanotubes to have a lower buoyant density than semiconducting carbon nanotubes of the same wall number. 
     
     
         16 . The method of  claim 12 , wherein the relative ratio of the two or more surface active components is selected to cause semiconducting carbon nanotubes to have a lower buoyant density than metallic carbon nanotubes regardless of wall number. 
     
     
         17 . A population of double-walled carbon nanotubes, wherein greater than about 50% of the double-walled carbon nanotubes comprise a metallic outer wall. 
     
     
         18 . A transparent conductive film comprising the population of  claim 17 . 
     
     
         19 . A population of double-walled carbon nanotubes, wherein greater than about 70% of the double-walled carbon nanotubes comprise a semiconducting outer wall. 
     
     
         20 . A thin film transistor comprising a semiconductor component comprising the population of  claim 19 .