Preparation and application of polyimide aerogel materials

Polyimide (PI) is a polymer with the imide ring on the major chain. Due to the stable structure of the rigid aromatic ring and conjugation effect of the aromatic heterocyclic ring of the imide ring, its bond energy of the main chain and intermolecular interaction are strengthened. Therefore, it has good mechanical properties, excellent chemical resistance, good dielectric properties and high temperature stability, with applicability as a high temperature engineering polymer with broad application potential. PI products, such as films, coatings, adhesives, photoelectric materials, advanced composite materials, microelectronic devices, separation films and photoresist, have been widely used in electronic information, fire and bulletproofing, aerospace, gas‒liquid separation, photoelectric liquid crystals and other fields. Polyimide aerogels (PIA) are cross-linked, three dimensional porous materials made up of polymer molecular chains, combining the excellent properties of PI and aerogels, such as lightweight, low density, high specific surface area, low coefficient of thermal conductivity and a low dielectric constant. Therefore, PIA are being rapidly investigated as an excellent organic aerogel for broad application in aerospace, electronic communications, heat insulations, flame retardants, sound absorption, adsorption cleaning and other fields. Since National Aeronautics and Space Administration (NASA) and other scientific research institutions have developed flexible PIA materials and successfully used them in military and civilian applications, sophisticated weapons, Mars exploration and other application fields, their application research and development has been expanded. Given the characteristics of the PIA materials and the need to improve the preparation process and properties, the preparation method, influencing factors (solvent effect, monomer structure and solid content), application and future development are discussed in this paper.