Preparation and properties of high dielectric polyimide composite using a core–shell C@SiC filler

Polyimide (PI) is very popular in polymer film capacitors due to its excellent performance and easy film-forming properties. However, its relatively low dielectric constant (approximately 3–4) limits its application and development in the field of high-performance capacitors. In general, dielectric constant can be enhanced effectively by adding special filler materials into polyimide. In this study, core–shell structured C@SiC nanoparticles were synthesized via a hydrothermal method. Novel polyimide composites (C@SiC/PI) were obtained by dispersing C@SiC nanoparticles into polyamic acid, followed by thermal imidization. The dielectric constant of C@SiC/PI composite material is as high as 40.2, which is 11.4 times that of pure PI. The maximal discharging energy density reached up to 2.49 J cm −3 with 10% C@SiC nanoparticles, which is almost 3 times higher than pure PI under identical conditions. Additionally, the composites have excellent thermal stability with a decomposition temperature of 5% above 530℃. The tensile strength of the composite film is in the range of 89.7–130.50 MPa, and the elongation at break is between 5.4% and 9.1%, maintaining good mechanical properties. Consequently, the fabricated composites hold significant promise for applications in polymer thin-film capacitors and flexible electronics.