Carbon Nanotube Foams with Controllable Architecture and Methods

Abstract

CNT foams and methods are provided. The methods may include forming, in a non-solvent liquid, a suspension of CNTs and particles of a pyrolytic polymer; removing the non-solvent liquid; and removing the particles of the pyrolytic polymer to produce a CNT foam having cells that at least substantially correspond to the dimensions of the particles of the pyrolytic polymer. CNT foams having porous structures also are provided.

I claim: 
     
         1 . A method for making a carbon nanotube (CNT) foam, the method comprising:
 forming a suspension comprising a non-solvent liquid in which CNTs and particles of a pyrolytic polymer are dispersed;   removing the non-solvent liquid; and   removing the particles of the pyrolytic polymer to produce a CNT foam having cells that at least substantially correspond to the dimensions of the particles of the pyrolytic polymer.   
     
     
         2 . The method of  claim 1 , wherein forming the suspension comprises (i) dispersing CNTs in the non-solvent liquid to form a CNT suspension, and (ii) adding the particles of the pyrolytic polymer to the CNT suspension. 
     
     
         3 . The method of  claim 1 , wherein the pyrolytic polymer comprises a thermoplastic polymer. 
     
     
         4 . The method of  claim 3 , wherein the thermoplastic polymer comprises poly(methylmethacrylate), nylon, polyesters, or a combination thereof. 
     
     
         5 . The method of  claim 1 , wherein the particles of the pyrolytic polymer have an average diameter of from about 0.1 micrometers to about 1,000 micrometers. 
     
     
         6 . The method of  claim 1 , wherein the average length of the CNTs is at least two times the average diameter of the particles of the pyrolytic polymer. 
     
     
         7 . The method of  claim 1 , wherein the average length of the CNTs is at least fifteen times the average diameter of the particles of the pyrolytic polymer. 
     
     
         8 . The method of  claim 7 , wherein the average length of the CNTs is about 500 micrometers and the average diameter of the particles of the pyrolytic polymer is about 30 micrometers. 
     
     
         9 . The method of  claim 1 , wherein the particles of the pyrolytic polymer are at least substantially spherical. 
     
     
         10 . The method of  claim 1 , wherein the weight ratio of pyrolytic polymer to CNTs in the suspension ranges from about 1:1 to about 60:1. 
     
     
         11 . The method of  claim 1 , wherein removing the particles of the pyrolytic polymer comprises a first heat treatment at a temperature effective to pyrolyze and evaporate the particles of the pyrolytic polymer. 
     
     
         12 . The method of  claim 1 , further comprising adding a carbonaceous binder precursor to the suspension prior to removing the non-solvent liquid, and converting the carbonaceous binder precursor to graphitic structures after removing the non-solvent liquid. 
     
     
         13 . The method of  claim 12 , wherein converting the carbonaceous binder precursor to graphitic structures comprises a second heat treatment. 
     
     
         14 . The method of  claim 13 , wherein the second heat treatment comprises heating the CNT foam to at least 800° C. 
     
     
         15 . The method of  claim 12 , wherein the weight ratio of carbonaceous binder precursor to CNTs in the suspension ranges from about 0.1:1 to about 5:1. 
     
     
         16 . The method of  claim 12 , wherein the carbonaceous binder precursor is selected from polyacrylonitrile, pitch, or a combination thereof. 
     
     
         17 . A CNT foam comprising mesopores, macropores, nanopores, or a combination thereof, wherein the CNT foam has a density of from about 1 to about 200 mg/cm 3 , a BET surface area of at least 50 m 2 /g, and a conductivity of at least 0.1 S/cm. 
     
     
         18 . The CNT foam of  claim 17 , further comprising graphitic structures. 
     
     
         19 . The CNT foam of  claim 17 , wherein the mesopores, macropores, nanopores, or a combination thereof are provided by cell walls having a thickness of from about 0.2 to about 2 micrometers. 
     
     
         20 . A method for making a carbon nanotube (CNT) foam, the method comprising:
 forming a suspension comprising a non-solvent liquid in which CNTs, particles of a pyrolytic polymer, and a carbonaeceous binder precursor are dispersed;   removing the non-solvent liquid;   removing the particles of the pyrolytic polymer to produce a CNT foam having cells that at least substantially correspond to the dimensions of the particles of the pyrolytic polymer; and   converting the carbonaceous binder precursor to graphitic structures.