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.

Formation mechanisms and morphological effects on multi-properties of carbon nanotube fibers and their polyimide aerogel-coated composites

“…A polyamic acid oligomer with a molar ratio of BPDA: ODA ¼ 26: 25 was formulated in NMP [20]. 1.2796 g of BPDA was added to a solution of ODA (0.8376 g) in 19.0 ml of NMP.…”

“…BPDA and ODA are commonly used as dianhydride and diamine monomers in polyimide resin and polyimide aerogels. Herein BPDA imparts the high temperature resistivity and glass transition temperature [25], while ODA provides a flexible backbone [20]. In addition, OAPS has been regarded as an effective way to enhance the thermal and mechanical properties of the polyimide nanocomposites [19,20].…”

Robust ambient pressure dried polyimide aerogels and their graphene oxide directed growth of 1D–2D nanohybrid aerogels using water as the only solvent

“…Many researchers especially NASA have carried innovative researches on the preparation of PI aerogels using various dianhydride and multifunctional amines, [16][17][18] and generally, high boiling point solvents like N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc) and N-methyl-2-pyrrolidone (NMP) are used to prepare the polyamic acid (PAA) precursor, followed by supercritical CO 2 dying to afford PI aerogels. Most of these high boiling points are very difficult to recycle and thus cause serious environmental pollution.…”

Direct preparation of green and renewable aerogel materials from crude bagasse

“…Organic aerogels represent an interesting alternative to the inorganic aerogels (Guo et al 2012) and can be subsequently converted to carbon aerogels by pyrol ysis, which are the only electron conductive aerogels.…”