A review on high temperature resistant polyimide films: Heterocyclic structures and nanocomposites

Polyimide (PI) films are used in a wide spectrum of high-tech fields including photovoltaics, microelectronics, and aerospace engineering thanks to their good heat resistance, large mechanical strength, and low thermal expansion coefficients. Further improving their temperature resistance is expected to expand its applications. However, great challenges still exist in the fabrication of PI film with high thermal stability and good combined properties. This review summaries the design strategies and synthesis route of high thermal stability PI films, and discusses the recent progress on improving the thermal stability of PI films by nanocomposite modification. Especically, reported results by introducing a heterocyclic ring into the polymer chain to improve thermal stability were presented. Inorganic particles such as layered silicate, nitrides or metal oxides, carbon nanotubes (CNTs) and graphene used to make organic/inorganic nanocomposite for PI modification were also discussed.