Polyimide composite films reinforced by graphene quantum dots

Polyimide composite films have been widely used in some advanced field of microelectronic devices, precision instruments and national defense applications. Graphene quantum dots have great application potential in polymer doping modification because of their good mechanical strength, high specific surface area and excellent tunability of physical and chemical properties. In this paper, Graphene quantum dots are prepared by pyrolysis at different temperatures. The results show that different reaction temperatures have a great influence on the size and size distribution of graphene quantum dots. When the pyrolysis temperature is 200 °C, the size of graphene quantum dots is uniform at 3–5 nm. Graphene quantum dots-polyimide nanocomposite films prepared by in-situ polymerization show excellent mechanical properties. When the doping amount of graphene quantum dots is 0.5 wt%, the tensile strength and elastic modulus of the composite films can reach 130.24 MPa and 2.93 GPa respectively, which are 41.3% and 108% higher than that of pure polyimide films, respectively. Moreover, the thermal stability of polyimide composite films increases with the increase of the doping amount of graphene quantum dots. This shows that graphene quantum dots have good dispersion in polyimide matrix and can effectively improve the interface of composites. These results provide a successful preparation method to help guide to fabricate graphene quantum dots-polyimide composite films with high performance for the advanced applications.