Porous nanostructured polyimide networks and methods of manufacture

Abstract

Porous three-dimensional networks of polyimide and porous three-dimensional networks of carbon and methods of their manufacture are described. For example, polyimide aerogels are prepared by mixing a dianhydride and a diisocyanate in a solvent comprising a pyrrolidone and acetonitrile at room temperature to form a sol-gel material and supercritically drying the sol-gel material to form the polyimide aerogel. Porous three-dimensional polyimide networks, such as polyimide aerogels, may also exhibit a fibrous morphology. Having a porous three-dimensional polyimide network undergo an additional step of pyrolysis may result in the three dimensional network being converted to a purely carbon skeleton, yielding a porous three-dimensional carbon network. The carbon network, having been derived from a fibrous polyimide network, may also exhibit a fibrous morphology.

1 . A method of manufacturing a three-dimensional nanostructured polyimide network, the method comprising:
 mixing an anhydride and an isocyanate in a solvent to form a sol-gel material; and   drying the sol-gel material to form the polyimide network.   
     
     
         2 . The method of  claim 1 , wherein the solvent comprises at least one of pyrrolidone and N-methyl-2-pyrrolidone. 
     
     
         3 . The method of  claim 1 , wherein the anhydride is pyromellitic dianhydride. 
     
     
         4 . The method of  claim 1 , wherein the isocyanate is 4,4′-diisocyanatodiphenylmethane. 
     
     
         5 . The method of  claim 1 , wherein the solvent further comprises at least one of acetonitrile, acrylonitrile, or acetone. 
     
     
         6 . The method of  claim 1 , further comprising a step of subjecting the sol-gel material to solvent-exchange using at least one of a pyrrolidone, acetonitrile, or acetone. 
     
     
         7 . The method of  claim 1 , wherein the drying the sol-gel material includes supercritical drying of the sol-gel material. 
     
     
         8 . The method of  claim 1 , wherein the drying the sol-gel material includes subcritical drying of the sol-gel material. 
     
     
         9 . A fibrous aerogel comprising:
 a three dimensional network of particles including polyimide, the three dimensional network having a fibrous morphology.   
     
     
         10 . An insulator, a lightweight structural material, an acoustic insulating material, or an impact dampening material comprising the aerogel of  claim 9 . 
     
     
         11 . The method of  claim 1 , further comprising pyrolyzing the polyimide network to form a carbon network. 
     
     
         12 . The method of  claim 11 , wherein the carbon network is chemically etched to produce a carbon network having increased microporosity. 
     
     
         13 . The carbon aerogel of  claim 11 . 
     
     
         14 . A fibrous aerogel comprising:
 a three dimensional network of nanoparticles including a carbon skeleton, the three dimensional network having a fibrous morphology.   
     
     
         15 . An electrode, a battery, a supercapacitor device, an insulator, a ballistic material, an ablative material, an armor comprising the aerogel of  claim 14 . 
     
     
         16 . A method of manufacturing an aerogel, the method comprising:
 mixing an anhydride and an isocyanate in a solvent in the presence of a ceramic oxide to form a sol-gel material;   drying the sol-gel material to form the hybrid polyimide aerogel; and   pyrolyzing the hybrid polyimide aerogel to form at least one of a metal aerogel, a metalloid aerogel, a metal carbide aerogel and a metalloid carbide aerogel.   
     
     
         17 . The method of  claim 16 , in which the ceramic oxide forms an interpenetrating network throughout a polyimide network. 
     
     
         18 . The method of  claim 16 , in which the ceramic oxide comprises one or more of a metal oxide, a metalloid oxide, or silicon oxide. 
     
     
         19 . The aerogel of  claim 16 . 
     
     
         20 . The method of  claim 1 , wherein the isocyanate comprises at least one of a diisocyanate, triisocyanate, and a polyisocyanate.