High dielectric performance and thermal conductivity dielectric composite film via vertical alignment of hybrid BaTiO3 nanofibers

The arrangement of anisotropic dielectric fillers in polymer matrix can lead to a significant enhancement of dielectric properties along a specific direction, enabling the rapid development of integrated circuits and high-performance microelectronic devices. In this work, magnetic barium titanate nanofibers/polyimide composite films (mBT NFs/PI) with vertically oriented structures were constructed with the assistant of magnetic field. The dielectric constant was significantly increased from 20.8 to 39.1 at a filler content of 30 wt%, as compared to the randomly aligned films. However, the breakdown strength was affected. Addressing this issue, an optimized core-shell structure was fabricated by introducing insulated and thermo-conductive boron nitride (BN) "shell" on the surface of mBT NFs by coaxial electrospinning. The obtained mBT@BN/PI nanocomposite exhibits improved thermal conductivity and breakdown strength, while maintaining a high dielectric constant. This work highlights an effective strategy to achieve excellent dielectric properties and thermal conductivity for high-temperature dielectric capacitor materials.