Preparation and properties of polyimide/LTNO composite films with high dielectric constant

To develop the polymer-based materials with high dielectric constant and thermal stability, Li and Ti doped NiO (LTNO) particles with super high dielectric constant (ε) were dispersed into pyromellitic dianhydride (PMDA) and 4, 4′-oxydianiline (ODA)-based polyimide. Through mixing LTNO particles with the poly(amic acid) precursor solution, casting film and following thermal curing, the polyimide/LTNO composite films were obtained. The thermal stability and structure of the composites were studied by TGA and X-ray diffraction, respectively. Dielectric and conductive measurements were adopted to investigate the properties of the samples. The results revealed that the obtained composites had good morphology stability, but their thermal resistances become a little lower in comparison with pure polyimide. With increasing the content of LTNO particles, ε and conductivity of the composite films increased greatly. For the sample with the LTNO content at 0.4 in volume fraction, ε was as high as 570 at the frequency of 100 Hz. It showed that doping LTNO particles into polyimide would be an efficient route to high ε composites.