Method for carbon nanotube purification

Abstract

A method for carbon nanotube purification, preferably including: providing carbon nanotubes; depositing a mask; and/or selectively removing a portion of the mask; and optionally including removing a subset of the carbon nanotubes and/or removing the remaining mask.

We claim: 
     
         1 . A method for carbon nanotube purification, comprising:
 coating a bed of carbon nanotubes (CNTs) with a polymer mask, the bed comprising metallic CNTs and semiconducting CNTs;   selectively heating the metallic CNTs, wherein the metallic CNTs transfer heat to the polymer mask such that:
 substantially all the polymer mask coating the metallic CNTs depolymerizes into at least one of constituent monomers or constituent oligomers; and 
 substantially none of the polymer mask coating the semiconducting CNTs depolymerizes; and 
   after substantially all the polymer mask coating the metallic CNTs depolymerizes, selectively removing the metallic CNTs, wherein the polymer mask coating the semiconducting CNTs protects the semiconducting CNTs during removal of the metallic CNTs.   
     
     
         2 . The method of  claim 1 , further comprising, after selectively removing the metallic CNTs, removing a remainder of the polymer mask. 
     
     
         3 . The method of  claim 2 , wherein removing the remainder of the polymer mask comprises depolymerizing the remainder of the polymer mask into at least one of constituent monomers or constituent oligomers, thereby exposing the semiconducting CNTs. 
     
     
         4 . The method of  claim 3 , wherein depolymerizing the remainder of the polymer mask comprises heating the remainder of the polymer mask above a threshold depolymerization temperature. 
     
     
         5 . The method of  claim 2 , wherein:
 before selectively heating the metallic CNTs, the bed of CNTs and the polymer mask are supported by a substrate; and   removing the remainder of the polymer mask comprises delaminating the remainder of the polymer mask from the substrate, wherein the semiconducting CNTs remain embedded in the remainder of the polymer mask during delamination.   
     
     
         6 . The method of  claim 1 , wherein the CNTs of the bed are arranged substantially in a single monolayer or partial monolayer. 
     
     
         7 . The method of  claim 6 , wherein substantially all CNTs of the bed are arranged substantially parallel to each other. 
     
     
         8 . The method of  claim 1 , wherein, after selectively removing the metallic CNTs, a metallic/semiconducting ratio of the bed of CNTs is less than 0.001. 
     
     
         9 . The method of  claim 1 , wherein the polymer mask coating the metallic CNTs depolymerizes via an unzipping process. 
     
     
         10 . The method of  claim 1 , wherein selectively heating the metallic CNTs comprises illuminating the bed of CNTs with light, wherein the light is more strongly absorbed by the metallic CNTs than by the semiconducting CNTs. 
     
     
         10 . ethod of  claim 10 , wherein illuminating the bed of CNTs with light comprises illuminating the bed of CNTs with light defining a wavelength bandwidth spanning more than 25 nm. 
     
     
         12 . The method of  claim 10 , further comprising, while selectively heating the metallic CNTs, providing additional heat to the polymer mask. 
     
     
         13 . The method of  claim 1 , wherein the polymer mask comprises a self-immolative polymer. 
     
     
         14 . The method of  claim 1 , wherein selectively removing the metallic CNTs comprises exposing the metallic CNTs and the remainder of the polymer mask to an etchant environment. 
     
     
         15 . A method for carbon nanotube purification, comprising:
 coating a bed of carbon nanotubes (CNTs) with a polymer mask, the bed comprising metallic CNTs and semiconducting CNTs;   selectively heating the metallic CNTs, wherein the metallic CNTs transfer heat to the polymer mask such that:   substantially all the polymer mask coating the metallic CNTs depolymerizes via an unzipping process; and   substantially none of the polymer mask coating the semiconducting CNTs depolymerizes, resulting in a remaining polymer mask that coats the semiconducting CNTs; and   after substantially all the polymer mask coating the metallic CNTs depolymerizes, separating the metallic CNTs from the semiconducting CNTs.   
     
     
         15 . The method of  claim 14 , wherein separating the metallic CNTs from the semiconducting CNTs comprises destroying the metallic CNTs, wherein the remaining polymer mask protects the semiconducting CNTs during destruction of the metallic CNTs. 
     
     
         16 . The method of  claim 15 , wherein destroying the metallic CNTs comprises exposing the metallic CNTs and the remaining polymer mask to an etchant environment. 
     
     
         17 . The method of  claim 15 , wherein:
 before selectively heating the metallic CNTs, the bed of CNTs and the polymer mask are supported by a substrate; and   separating the metallic CNTs from the semiconducting CNTs comprises delaminating the remaining polymer mask from the substrate, wherein the semiconducting CNTs remain embedded in the remaining polymer mask during delamination.   
     
     
         17 . method of  claim 17 , further comprising, after delaminating the remaining polymer mask from the substrate, transferring the semiconducting CNTs onto a second substrate. 
     
     
         19 . The method of  claim 15 , wherein the polymer mask comprises a self-immolative polymer. 
     
     
         20 . The method of  claim 19 , wherein the self-immolative polymer comprises at least one of: poly(N-isopropyl acrylamide), poly(N-ethylpyrrolidine methacrylate), poly(phthalaldehyde), poly(4,5-dichlorophthalaldehyde), poly(methyl glyoxylate), poly(carbamate), polyurethane, polycarbonate, or poly(benzyl ether).