Enhancement of dielectric constant of polyimide by doping with modified silicon dioxide@titanium carbide...

Electrode materials used in supercapacitors must have a high dielectric constant and a low dielectric loss along with good mechanical properties. In this study, the dielectric constant of polyimide (PI) was improved by preparing a PI/SiO₂@TiC composite. A homogeneous dispersion of SiO₂@TiC nanoparticles was obtained by the hydrolyzation of tetraethyl orthosilicate, which resulted in the formation of a thin layer of SiO₂ on TiC particles. Polyamic acid was doped with the modified SiO₂@TiC nanoparticles by mechanical blending to synthesize the PI/SiO₂@TiC composite, and its dielectric properties were investigated. Scanning electron microscopy studies confirmed that the SiO₂@TiC particles were homogeneously dispersed in the PI matrix and did not exhibit agglomeration. An increase in the SiO₂@TiC filler content increased the dielectric constant and the dielectric loss of the composite, but decreased its breakdown strength and deteriorated its mechanical properties. Thus, the addition of SiO₂@TiC particles to PI is suitable for improving its dielectric properties while maintaining its flexibility.