Polyimide-based Nanocomposites as Low-Temperature Dielectrics

Introducing nanomaterials into a polymer can drastically change the properties of the host material. The resulting nanocomposites often possess new characteristics and can be used in an expanded range of applications. In this study, polyimide (PI) nanocomposites embedded with silicon dioxide (SiO2) nanoparticles were fabricated using two different approaches: a sol-gel process that involves chemical reactions and a physical mixing process. The distribution of the SiO2 nanoparticle in the resulting samples was inspected with scanning electron microscopy (SEM). The results showed that the sol-gel process produced uniformly distributed nanoparticles in the host polymer while the direct mixing process resulted in nanoparticle agglomeration. The dielectric performance of the sol-gel films was evaluated using high-voltage DC breakdown testing. The structure around the breakdown point was inspected by the SEM. The dielectric strengths of the nanocomposites, with 4 wt.% and 10 wt.% SiO2 contents, were obtained at 300 K and 164 K. This preliminary investigation shows that the PI-based nanocomposites are promising candidates as low-temperature dielectrics. Further research into this subject matter can bring additional benefits into PI-based nanocomposites for many other applications.