Thermally treated polyamic amide aerogel
Thermally treated aerogel compositions that include polyamic amides in an amount less than the aerogel compositions that include polyamic amides prior to thermal treatment, and articles of manufacture that include or are manufactured from the aerogel compositions are described.
1. A method of making, a thermally treated polyamic amide aerogel, the method comprising:
(a) providing at least one diamine compound to a solvent to form a solution;
(b) providing at least one dianhydride compound to the solution of step (a) under conditions sufficient to form a polyamic acid solution;
(c) providing a secondary amine to the polyamic acid solution;
(d) subjecting the solution of step (c) to conditions suitable to produce a polymer matrix solution comprising a polyamic amide;
(e) subjecting the polymer matrix solution to conditions sufficient to form an aerogel comprising an open-cell structured polymer matrix having a polyamic amide; and
thermally treating the (e) polyamic amide aerogel at a temperature sufficient to lower the amount of the polyamic amide in the aerogel.
2. The method of claim 1 , wherein step (f) conditions comprise heating the aerogel at a temperature of 275° C. to 550° C., or 290° C. to 500° C., or 300° C. to 350° C., to produce a thermally treated polyimide aerogel.
3. The method of claim 2 , wherein step (f) is performed under an inert atmosphere or in air.
4. The method of claim 1 , further comprising subjecting the thermally treated polyamic amide aerogel to a second temperature cycle, under vacuum or in air to remove compounds not chemically bound to the polymer matrix.
5. The method of claim 1 , wherein the thermally treated polyamic amide aerogel includes at least 0.01 wt. % and up to 4.95 wt. % of the polyamic amide polymer.
6. The method of claim 1 , wherein thermally treating reduces the amount of polyamic amide in the aerogel by at least 15%, or at least 50%.
7. The method of claim 1 , wherein the secondary amine is a substituted or an unsubstituted cyclic amine, a substituted or an unsubstituted aromatic amine, or combinations thereof.
8. The method of claim 1 , wherein secondary amine further comprises at least one secondary nitrogen and at least one tertiary nitrogen.
9. The method of claim 8 , wherein the secondary amine is imidazole or a substituted imidazole, a triazole or a substituted triazole, a tetrazole or substituted tetrazole, a purine or a substituted purine, a pyrazole or a substituted pyrazole, or combinations thereof.
10. The method of claim 9 , wherein the nitrogen atoms are separated by at least one carbon atom.
11. The method of claim 1 , wherein the secondary amine in step (c) has the following general structure:
where R 3 , R 4 , and R 5 are each individually a hydrogen, an alkyl group, or a substituted alkyl group, or an aromatic group or a substituted group, or R 4 , and R 5 come together with other atoms to form a cyclic structure.
12. The method of claim 11 , wherein the alkyl group has 1 to 12 carbon atoms.
13. The method of claim 11 , wherein R 3 is a methyl group or an ethyl group, and R 4 and R 5 are H atoms, an alkyl group, or a substituted alkyl.
14. The method of claim 13 , wherein R 3 is a methyl group and R 4 and R 5 are H atoms.
15. The method of claim 14 , wherein R 3 is an ethyl group and R 4 and R 5 are each individually a H atom, an alkyl group, or a substituted alkyl.
16. The method of claim 1 , wherein step (d) comprises providing a dehydrating agent prior to, during, or after, adding the secondary amine.
17. The method of claim 1 , wherein step (e) comprises forming a gel from the solution and removing the solvent from the gel.
18. The method of claim 17 , comprising subjecting the gel to a drying step to remove the solvent.
19. The method of claim 18 , wherein the drying step comprises supercritical drying, subcritical drying, thermal drying, evaporative air drying, vacuum drying, or any combination thereof.
20. The method of claim 19 , wherein drying comprises evaporative air drying.
21. The method of claim 19 , wherein the drying step comprises:
(i) subjecting the gel to conditions sufficient to freeze the solvent to form a frozen material; and
(ii) subjecting the frozen material to a subcritical drying step sufficient to form an open-cell structure.
22. The method of claim 1 , further comprising subjecting the gel to at least one solvent exchange with a different solvent prior to drying the gel.
23. The method of claim 22 , wherein at least one solvent exchange is performed with acetone.