title: Polyimide aerogels with amide cross-links: a low cost alternative for mechanically strong polymer aerogels.
abstract: Polyimide aerogels combine high porosity, low thermal conductivity, flexibility, and low density with excellent mechanical properties. However, previously used cross-linkers, such as 1,3,5-triaminophenoxybenzene (TAB), 2,4,6-tris(4-aminophenyl)pyridine (TAPP), or octa(aminophenoxy)silsesquioxane (OAPS), either are not commercially available or are prohibitively expensive. Finding more cost efficient cross-linkers that are commercially available to synthesize these aerogels is crucial for making large scale manufacturing attractive. Herein, we describe an approach to making polyimide aerogels starting with amine capped oligomers that are cross-linked with 1,3,5-benzenetricarbonyl trichloride (BTC). BTC is a lower cost, commercially available alternative to TAB, TAPP, or OAPS. Aerogels made in this way have the same or higher modulus and higher surface area compared to those previously reported with either TAB or OAPS cross-links at the same density. While the cross-link structure is an amide, the thermal stability is not compromised most likely because the cross-link is only a small part of the composition of the aerogel. Onset of decomposition depends primarily on the backbone chemistry with 4,4'-oxidianiline (ODA) being more thermally stable than 2,2'-dimethylbenzidine (DMBZ), similar to those previously reported with other cross-links.
authors.affiliation: NASA Glenn Research Center , 21000 Brookpark Road, Cleveland, Ohio 44135, United States.
authors.forename: Mary Ann B
authors.initials: MA
authors.lastname: Meador
authors.forename: Christian R
authors.initials: CR
authors.lastname: Alemán
authors.forename: Katrina
authors.initials: K
authors.lastname: Hanson
authors.forename: Nakaira
authors.initials: N
authors.lastname: Ramirez
authors.forename: Stephanie L
authors.initials: SL
authors.lastname: Vivod
authors.forename: Nathan
authors.initials: N
authors.lastname: Wilmoth
authors.forename: Linda
authors.initials: L
authors.lastname: McCorkle
keywords: aerogel; cross-linked; mesoporous; polyamide; polyimide