title: Mechanically strong, flexible polyimide aerogels cross-linked with aromatic triamine.
abstract: Polyimide gels are produced by cross-linking anhydride capped polyamic acid oligomers with aromatic triamine in solution and chemically imidizing. The gels are then supercritically dried to form nanoporous polyimide aerogels with densities as low as 0.14 g/cm(3) and surface areas as high as 512 m(2)/g. To understand the effect of the polyimide backbone on properties, aerogels from several combinations of diamine and dianhydride, and formulated oligomer chain length are examined. Formulations made from 2,2'-dimethylbenzidine as the diamine shrink the least but have among the highest compressive modulus. Formulations made using 4,4'-oxydianiline or 2,2'dimethylbenzidine can be fabricated into continuous thin films using a roll to roll casting process. The films are flexible enough to be rolled or folded back on themselves and recover completely without cracking or flaking, and have tensile strengths of 4-9 MPa. Finally, the highest onset of decomposition (above 600 °C) of the polyimide aerogels was obtained using p-phenylene diamine as the backbone diamine with either dianhydride studied. All of the aerogels are suitable candidates for high-temperature insulation with glass transition temperatures ranging from 270-340 °C and onsets of decomposition from 460-610 °C.
authors.affiliation: NASA Glenn Research Center, 21000 Brookpark Road, Cleveland, Ohio 44135, United States. maryann.meador@nasa.gov
authors.forename: Mary Ann B
authors.initials: MA
authors.lastname: Meador
authors.forename: Ericka J
authors.initials: EJ
authors.lastname: Malow
authors.forename: Rebecca
authors.initials: R
authors.lastname: Silva
authors.forename: Sarah
authors.initials: S
authors.lastname: Wright
authors.forename: Derek
authors.initials: D
authors.lastname: Quade
authors.forename: Stephanie L
authors.initials: SL
authors.lastname: Vivod
authors.forename: Haiquan
authors.initials: H
authors.lastname: Guo
authors.forename: Jiao
authors.initials: J
authors.lastname: Guo
authors.forename: Miko
authors.initials: M
authors.lastname: Cakmak
mesh_terms: D000588:Amines / Q000737:chemistry*; D001555:Benzene Derivatives / Q000737:chemistry; D005782:Gels / Q000737:chemistry; D036103:Nanotechnology; D011108:Polymers / Q000737:chemistry; D016062:Porosity; D012117:Resins, Synthetic / Q000737:chemistry*; D013696:Temperature
chemical_list: D000588:Amines; D001555:Benzene Derivatives; D005782:Gels; D011108:Polymers; D012117:Resins, Synthetic; C513053:polyamic acid; C029945:polyimide resin