Lightweight and strong toughness of polyimide/SiO₂ composite aerogels with super-high working temperature for high-performance thermal insulation and flame-resistant application

As the continuous development of aerospace and outer space exploration, high-performance thermal insulation materials with high-temperature resistance and attractive mechanical properties have always been a fascinating topic of research to protect human body or components from extreme environments. In this research, hydrophobic silicon dioxide (SiO₂) nanoparticles as molecular skeleton enhancers and heat transfer inhibitors are introduced in crosslinked polyimide (PI) aerogels with rigid molecular structure to maintain the stable nanoporous network structure. The density, shrinkage, porosity, specific surface area and pore size distribution of PI/SiO₂ composite aerogels can be adjusted by the addition of SiO₂ nanoparticles, so as to improve the comprehensive performances. The excellent thermal stability and mechanical properties of PI/SiO₂ composite aerogels with super-high working temperature of over 550 °C and high modulus of compression and tension (compression Young’s modulus of 37.75 MPa and tensile modulus of 237.1 MPa) ensure their use as a structural component. The charming thermal conductivity (29.7 mWm⁻¹ K⁻¹) and excellent flame resistance make them a candidate for high-performance thermal insulation materials.