Polyalkylene imide aerogels and processes for making the same

Patent metadata

Field	Value
Publication number	US-9650487-B1
Application number	US-201514698084-A
Country	US
Kind code	B1
Filing date	Apr 28, 2015
Priority date	Jun 20, 2014
Publication date	May 16, 2017
Grant date	May 16, 2017

Abstract

An aerogel and process of making the aerogel are provided. The aerogel is a polyimide aerogel having polyamide cross-links formed using a poly(maleic anhydride) cross-linker.

First claim

The invention claimed is:

1. An aerogel, comprising:
a polyimide oligomer; and
a poly(maleic anhydride) cross-linker, the poly(maleic anhydride) cross-linker connected to the polyimide oligomer, the polyimide oligomer comprising a diamine and a dianhydride in a ratio of (n+1) to n where n is the number of repeat units in the polyimide oligomer.

2. The aerogel of claim 1 , the poly(maleic anhydride) cross-linker being selected from the group comprising poly(maleic anhydride-alt-1-octadecene), poly(ethylene-alt-maleic anhydride), poly (isobutylene-alt-maleic anhydride), and poly(methyl vinyl ether-alt-maleic anhydride).

3. The aerogel of claim 1 wherein the diamine is 4, 4′-oxidianiline.

4. The aerogel of claim 1 wherein the diamine is a combination of 2, 2′-dimethylbenzidine and 4, 4′-oxidianiline.

5. The aerogel of claim 1 wherein the diamine is poly(propylene glycol) bis(2-aminopropyl ether) (PPG-230).

6. The aerogel of claim 1 wherein the diamine is poly(propylene glycol) bis(2-aminopropyl ether) (PPG-400).

7. The aerogel of claim 6 wherein the aerogel has a contact angle of up to 124°.

8. The aerogel of claim 1 wherein the diamine is 2, 2′-dimethylbenzidine.

9. The aerogel of claim 1 wherein the aerogel has a porosity of greater than 88%.

10. The aerogel of claim 1 , the polyimide oligomer comprising an aliphatic diamine.

11. A process for making a polyimide aerogel, comprising:
providing a poly(amic acid) oligomer solution;
adding poly(maleic anhydride) to the poly(amic acid) oligomer solution to cross-link poly(amic acid) oligomers of the poly(amic acid)oligomer solution; and
chemically imidizing the cross-linked poly(amic acid) oligomers of the provided poly(amic acid) solution to form a polyimide oligomer solution, wherein the polyimide oligomers are amine terminated.

12. The process of claim 11 , the step of creating the polyimide oligomer solution further comprises:
generating amine-capped polyimide oligomers, the generating comprising:
dissolving diamine in solution;
adding dianhydride to the diamine in solution;
adding acetic anhydride to the anhydride and diamine solution and mixing; and
adding acetic anhydride and triethylene amine to form a cross-linked polyimide gel.

13. The process of claim 12 , further comprising drying the cross-linked polyimide gel.

14. The process of claim 11 , comprising:
dissolving the poly(amic acid) oligomers N-methyl-2-pyrrolidone (NMP) to form a solution.

15. The process of claim 11 , comprising:
chemically imidizing the cross-linked poly(amic acid) oligomers into polyimide at room temperature using acetic anhydride and triethyleneamine.

16. The process of claim 14 , comprising:
allowing the solution to gel.

17. The process of claim 16 , comprising:
converting the gel to an aerogel by supercritical fluid extraction.

18. The process of claim 12 , wherein the polyimide solution comprises various dianhydrides and diamines.

19. The process of claim 12 , wherein the dianhydrides are selected from a group consisting of benzophenone-3,3′,4,4′-tetracarboxylic dianhydride (BTDA) and biphenyl-3,3′,4,4′-tetracarboxylic dianhydride (BPDA).

20. The process of claim 12 , wherein the diamines are selected from a group consisting of 3,4-oxydianiline (3,4-ODA), 4,4-oxydianiline (4,4-ODA or ODA), p-phenylene diamine (PPDA), DMBZ, 4,4-bis(4-aminophenoxy)biphenyl, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, bisaniline-p-xylidene (BAX), m-phenylenediamine, 4,4-bis(aminophenoxy)-2,2-dimethylbiphenyl (BAPD), 4,4′-[1,3-phenylenebis(1-methyl-ethylidene)]bisaniline (bisaniline-M), 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane (HFBAPP), and (poly(propylene glycol) bis(2-aminopropyl ether) (PPG-230 or PPG-400).

21. The process of claim 11 , further comprising:
dissolving diamines in solution before adding a dianhydride;
dissolving the dianhydride; and
chemically imidizing the cross-linked poly(amic acid) oligomers into polyimide.

22. The process of claim 11 , the poly(maleic anhydride) being selected from a group consisting of:
poly(maleic anhydride-alt-1-octadecene), poly(ethylene-alt-maleic anhydride), poly (isobutylene-alt-maleic anhydride), and poly(methyl vinyl ether-alt-maleic anhydride).

23. The process of claim 11 , wherein the solution can be cast into a mold to form special shapes or cast as a film and then forms a gel.

24. The process of claim 11 , wherein the poly(maleic anhydride) cross-linked polyimide aerogel made with 50% DMBZ+50% ODA has a lower shrinkage and a lower density than those made with DMBZ or ODA after heated at 200° C. and 300° C.

Assignees

• Nasa
• The Us Administrator Of Nat Aeronautics And Space Administration

Inventors

• Guo Haiquan
• Meador Mary Ann B

Classifications

• C08J9/0023

  containing oxygen · CPC title

• C08J9/28 Primary

  by elimination of a liquid phase from a macromolecular composition or article, e.g. drying of coagulum · CPC title

• C08J2379/08

  Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors · CPC title

• C08J9/286

  the liquid phase being a solvent for the monomers but not for the resulting macromolecular composition, i.e. macroporous or macroreticular polymers · CPC title

• C08J9/0028

  containing nitrogen · CPC title