title: Tailoring properties of cross-linked polyimide aerogels for better moisture resistance, flexibility, and strength.
abstract: Combinations of rigid and flexible aromatic diamines were used to tailor the properties of octa(aminophenyl)-silsesquioxane (OAPS) cross-linked polyimide aerogels. 2,2'-Dimethylbenzidine (DMBZ) or p-phenylenediamine (PPDA) was used in combination with the more-flexible diamine, 4,4'-oxydianiline (ODA). The amount of rigid diamine was varied from 0% to 100% of the total diamines in the backbone. The resulting aerogels vary in density, shrinkage, porosity, surface area, mechanical and thermal properties (depending on the type of diamine and the proportions of rigid diamine to flexible diamine used). Replacing ODA with PPDA increases shrinkage that occurs during gelation and processing, while increasing the DMBZ fraction decreases shrinkage. Replacing ODA with 50 mol% of DMBZ maintains the flexibility of thin films, while the moisture resistance of the aerogels is greatly improved.
authors.affiliation: Ohio Aerospace Institute, 22800 Cedar Point Road, Cleveland, Ohio 44142, USA. haiquan.n.guo@nasa.gov
authors.forename: Haiquan
authors.initials: H
authors.lastname: Guo
authors.forename: Mary Ann B
authors.initials: MA
authors.lastname: Meador
authors.forename: Linda
authors.initials: L
authors.lastname: McCorkle
authors.forename: Derek J
authors.initials: DJ
authors.lastname: Quade
authors.forename: Jiao
authors.initials: J
authors.lastname: Guo
authors.forename: Bart
authors.initials: B
authors.lastname: Hamilton
authors.forename: Miko
authors.initials: M
authors.lastname: Cakmak