Enhanced Dielectric Properties of Polyimide/BaTiO3 Nanocomposite by Embedding the Polypyrrole@Polyimide Core-Shell Nanoparticles

A three-phase polymer composite with a ferroelectric phase (BaTiO3) and conductive core-shell polypyrrole@ polyimide (PPy@PI) nanoparticles embedded in a polyimide (PI) matrix was prepared by using a simple direct mixing and solution casting process. PPy@PI nanoparticles as the conductive filler were synthesized to obtain homogeneous dispersion in the PI matrix. The dependence of the dielectric behavior on the BaTiO3 and PPy@PI contents was studied over a wide frequency range from 10 kHz to 1 MHz. The incorporation of low loading levels of PPy@PI nanoparticles to the PI/BaTiO3 system led to a significant enhancement in the dielectric constant with suppressed loss. The dielectric constant (Dk) of the PI/BaTiO3/PPy@PI (25/75/5) hybrid was 58.53 at 10 kHz, i.e., three times higher than that of the PI/BaTiO3 (25/75) nanocomposite without PPy@PI. The fairly improved dielectric properties were due to the synergistic enhancement of the ferroelectric ceramic filler, BaTiO3, and conductive filler, PPy@PI nanoparticles, as well as due to homogeneous dispersion. Such polymer composites have the potential for use in fabricating embedded capacitors, and specimens with various shapes can be easily obtained owing to the flexibility of the nanocomposite.