Enhanced dielectric properties in polyimide nanocomposites containing barium titanate@ polydopamine core-shell nanoparticles

In this work, we prepared the polyimide (PI) nanocomposite films containing barium titanate @polydopamine ([email protected]) nanoparticles within a core-shell structure by solution casting method. The dielectric constant of these nanocomposite films is significantly improved compared to pure PI film, and increases with the increase of BT nanoparticles. And, the breakdown strength of these nanocomposite films is better than that of untreated BT/PI films at the fixed BT content. The PI composite film containing 1 vol% of [email protected] nanoparticles exhibits the highest energy storage density of 1.94 J/cm3 under an electric field of 315 kV/mm, which is 42% over the pristine PI (1.37 J/cm3 at 295 kV/mm) and about 162% greater than biaxially-oriented polypropylene (BOPP) (≈1.2 J/cm3 at 640 kV/mm). The presence of PDA shell effectively improves the dispersion uniformity and interfacial compatibility of BT nanoparticles in the PI matrix, giving rise to lower local electric field distortion in the composites. Besides, the [email protected]/PI nanocomposite films have excellent dielectric thermal stability in the temperature range from 25 to 200 °C and thermal stability up to 500 °C. The [email protected]/PI composites fabricated in this work have a great potential to be used in the high-temperature film capacitors.