Dielectric and conduction properties of polyimide/silica nano-hybrid films

Dielectric and conduction properties of polyimide/silica nano-hybrid films were investigated with the silica content and the testing frequency, using a small electrode system. The hybrid films were prepared through solgel process and thermal imidization, by using pyromellitic dianhydride and 4,4′-oxydianiline as polyimide precursors, and tetraethoxysilane and methyltriethoxysilane as silica precursors. The dielectric coefficient of Pl/SiO₂ films was monotonically increased with increasing silica content, and decreased with increasing testing frequency. The dielectric loss of Pl/SiO₂ films had no obvious changes with increasing silica content, but monotonically increased with increasing testing frequency. These can be contributed to the different quantity and migration chunnels of current carriers, which were mainly influenced by a few of complicated factors. There were remarkable differences between conduction property of Pl/TEOS-SiO ₂ films and Pl/MTEOS-SiO₂ films because of the different size and dispersion status of silica particles in the polyimide matrix.