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 polyimide aerogel, the method comprising:
mixing an anhydride and a triisocyanate in a solvent to form a sol-gel material; and
drying the sol-gel material to form the polyimide aerogel.
2. The method of claim 1 , wherein the solvent comprises a pyrrolidone.
3. The method of claim 1 , wherein the anhydride is pyromellitic dianhydride.
4. The method of claim 1 , wherein the solvent further comprises acetonitrile, acrylonitrile, and/or acetone.
5. The method of claim 1 , further comprising a step of subjecting the sol-gel material to solvent-exchange using a pyrrolidone, acetonitrile, and/or acetone.
6. The method of claim 1 , wherein the drying the sol-gel material includes supercritical drying of the sol-gel material.
7. The method of claim 1 , wherein the drying the sol-gel material includes subcritical drying of the sol-gel material.
8. The method of claim 1 , further comprising pyrolyzing the polyimide aerogel to form a carbon network.
9. The method of claim 8 , wherein the carbon network is chemically etched to produce a carbon network having increased microporosity.
10. The method of claim 2 , wherein the pyrrolidone is N-methyl-2-pyrrolidone.