Multifunctional porous aramids (aerogels) and fabrication thereof
The present disclosure provides a series of new and improved porous polyamide aerogels derived from multifunctional aromatics that combine the high mechanical strength of aramids with the pore structure of aerogels. The polyamide aerogels have a hyperbranched structure, relatively low density, high porosity and may be derived from functionalized monomers having more aromatic groups than functional groups. The present disclosure also provides a new method for producing the porous polyamide aerogels by polymerizing an aromatic multifunctional carboxylic acid or a ferrocene multifunctional carboxylic acid with a polyfunctional aromatic isocyanate at moderate reaction conditions followed by drying with liquid CO 2 . Also disclosed are various methods of use of these polyamide aerogels in a variety of applications.
1. A polymeric ferrocene carboxamide aerogel comprising the following repeating units:
wherein:
G represents a group selected from aryl, (aryl)-R-(aryl), and (aryl)-R-(aryl) 2 ; where each aryl independently represents an optionally substituted aromatic ring; and where R is a bond or a C 1 -C 6 straight chain or branched chain alkyl group;
G 2 represents a ferrocenyl moiety; and
(*) denotes a linkage point.
2. The ferrocene carboxamide aerogel of claim 1 having a hyperbranched structure.
3. The ferrocene carboxamide aerogel of claim 1 wherein G is a triphenylmethane group of the following formula:
where the (*)s denote the linkage points on the linking bonds; and
where the linking bonds may be independently attached on their respective phenyl rings at the 2-position, 3-position or 4-position.
4. The ferrocene carboxamide aerogel of claim 3 , in which each of the linking bonds on the phenyl rings is attached at the 4-position of its respective phenyl ring.
5. A ferrocene carboxamide aerogel represented by the formula:
wherein:
G represents a group selected from aryl, (aryl)-R-(aryl), and (aryl)-R-(aryl) 2 ; where each aryl independently represents an optionally substituted aromatic ring; and where R is a bond or a C 1 -C 6 straight chain or branched chain alkyl group;
G 2 represents a ferrocenyl moiety;
(*) denotes a linkage point; and
q is an integer in the range of 2-10000.
6. The ferrocene carboxamide aerogel of claim 5 wherein G is a triphenylmethane of the following formula:
where the (*)s denote the linkage points on the linking bonds; and
where the linking bonds may be independently attached on their respective phenyl rings at the 2-position, 3-position or 4-position.
7. The ferrocene carboxamide aerogel of claim 6 , in which each of the linking bonds on the phenyl rings is attached at the 4-position of its respective phenyl ring.
8. The ferrocene carboxamide aerogel of claim 5 obtained by the reaction of 1,1′-ferrocene dicarboxylic acid with a tris(isocyanato) compound of the formula G(N═C═O) 3 , followed by decarboxylation; wherein G represents a group as defined in claim 5 .
9. The ferrocene carboxamide aerogel of claim 8 wherein the tris(isocyanato) compound is tris(4-isocyanatophenyl)methane.
10. A method for producing a polymeric ferrocene carboxamide aerogel comprising the reaction step of mixing together a multifunctional ferrocene carboxylic acid and a polyfunctional aromatic isocyanate in an anhydrous aprotic solvent.
11. The method of claim 10 wherein the polyfunctional aromatic isocyanate is tris(4-isocyanatophenyl)methane.
12. The method of claim 10 wherein the multifunctional ferrocene carboxylic acid is 1,1′-ferrocene dicarboxylic acid.
13. The method of claim 10 wherein the anhydrous aprotic solvent is a carboxamide solvent selected from the group consisting of DMF, DMA and NMP.
14. The method of claim 13 wherein the aprotic solvent is DMF.
15. The product obtained by the pyrolysis of the ferrocene carboxamide aerogel of claim 5 in the temperature range 500-1400° C.
16. The product obtained by the graphitization of the ferrocene carboxamide aerogel of claim 5 in the temperature range 500-2300° C.
17. The transmetalation product obtained by partial or complete replacement of the iron in any of the products of any one of claims 15 - 16 with another metal.
18. The transmetalation product of claim 17 , wherein the other metal is selected from the group consisting of Au, Pd, and Pt.
19. A method of catalysis of a chemical reaction in a mixture, the method comprising the step of contacting the mixture with a catalytic amount of the transmetalation product of claim 18 .
20. The method of claim 19 , wherein the chemical reaction is selected from the group consisting of reduction of a nitro compound, oxidation of an alcohol, and a Heck coupling reaction.