Mechanically strong polyimide aerogels containing benzimidazole groups with excellent flame-retardant, thermal insulation and high service temperature

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2023-04, Vol.461, p.141722, Article 141722
• Main Authors: Li, Dandan, Ke, Zhao, Xu, Ke, Dai, Fengna, Wang, Mengxia, Chen, Chunhai, Qian, Guangtao, Yu, Youhai
• Format: Article
• Language: English
• Subjects: Aromatic heterocyclic; Flame resistant; Mechanical behavior; Polyimide; Thermal insulation
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2023.141722

•Aromatic heterocyclic PI aerogels have been prepared by supercritical CO2 drying.•By adding PABZ, the morphology structure of PI aerogels is adjusted to fiber-island from tangled nanofibers.•Aerogels show outstanding mechanical behavior and thermal insulation (0.05 W/m·K).•PI aerogels also have rapid self-extinguishing and excellent flame retardant. The poor mechanical properties of polyimide (PI) aerogels made from biphenyl-3,3′,4,4′-tetracarboxylic dianydride (BPDA) and 4,4′-oxidianiline (ODA) limit their application. In this paper, an aromatic heterocyclic diamine, 5-amino-2-(4-aminophenyl)benzimidazole (PABZ) was introduced into the BPDA/ODA backbone to improve the comprehensive performance. The obtained PI aerogels represented excellent mechanical properties. The compressive Young’s modulus was up to 53.9 MPa and the stress at 10 % strain was as high as 2.39 MPa. Meanwhile, the tensile Young’s modulus ranged from 234 to 464 MPa and the tensile strength was up to 2.40 MPa. At the same time, all formulations of PI aerogels possessed outstanding thermal insulation, superb flame resistant and self-extinguishing performances, promising to be good candidates for special protective materials. Furthermore, the correlation between changes in morphology and structure resulting from the introduction of PABZ and PI aerogel properties was systematically analyzed.