Ultralight and heat-insulating mesoporous polyimide aerogels cross-linked with aminated SiO₂ nanoparticles

Ideally, excellent heat-insulating material should have low thermal conductivity, low density, excellent resistance to high and low temperatures and good mechanical properties. But few materials can meet all the above requirements at the same time. Take polyimide (PI) aerogel as an example. Although it has the advantages of lightweight, good mechanical properties and excellent temperature resistance, the value of its thermal conductivity is often unsatisfactory. To solve this problem, a series of mesoporous polyimide aerogels using aminated SiO₂ nanoparticles as cross-linker have been prepared. By changing the content of SiO₂ and the synthetic methods, the key properties of PI aerogels such as the density and thermal conductivity were effectively tuned. These aerogels have low density, high specific modulus, significantly low thermal conductivity (~20 mW m⁻¹ K⁻¹), and excellent high temperature resistance. Their general properties (shrinkage, density, compression performances, specific surface area, pore size distribution, high temperature resistance) and their application potential as lightweight, high-performance thermal insulation materials in harsh environments are discussed.