US 12,077,639 B2
Aqueous polyimide processes
Nicholas Leventis, Worcester, MA (US); Roxana Trifu, Worcester, MA (US); Redouane Begag, Hudson, MA (US); George L. Gould, Mendon, MA (US); Nicholas A. Zafiropoulos, Wayland, MA (US); and Harris R. Miller, Sharon, MA (US)
Assigned to Aspen Aerogels, Inc., Northborough, MA (US)
Filed by Aspen Aerogels, Inc., Northborough, MA (US)
Filed on Dec. 9, 2021, as Appl. No. 17/546,761.
Claims priority of provisional application 63/124,451, filed on Dec. 11, 2020.
Claims priority of provisional application 63/124,458, filed on Dec. 11, 2020.
Prior Publication US 2022/0185970 A1, Jun. 16, 2022
Int. Cl. C08J 3/075 (2006.01); C01B 32/05 (2017.01)
CPC C08J 3/075 (2013.01) [C01B 32/05 (2017.08); C08J 2379/08 (2013.01)] 14 Claims
OG exemplary drawing
 
1. A method of forming a polyimide aerogel, the method comprising:
providing an aqueous solution of a polyamic acid salt, the polyamic acid salt comprising a polyamic acid including carboxylic acid groups, wherein the carboxylic acid groups are associated with an alkali metal cation and greater than 95% of the carboxylic acid groups are present as carboxylate anions, wherein providing the aqueous solution of the polyamic acid salt comprises:
providing a polyamic acid;
adding the polyamic acid to water to form an aqueous suspension of the polyamic acid; and
adding an alkali metal hydroxide to the aqueous suspension of the polyamic acid to form the aqueous solution of the polyamic acid salt;
imidizing the polyamic acid salt to form a polyimide gel; and
drying the polyimide gel to form the polyimide aerogel.