POROUS NANOSTRUCTURED POLYIMIDE NETWORKS AND METHODS OF MANUFACTURE
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.