Heterogeneous BaTiO3@Ag core-shell fibers as fillers for polymer dielectric composites with simultaneously improved dielectric constant and breakdown strength

Interfacial polarization between fillers and polymer matrix in polymer composites would be responsible for enhancement of dielectric constant ( e ˊ ), but the dielectric mismatch between fillers and polymer also leads to an undesirable electric breakdown. Herein, we successfully developed a core-shell structured barium titanate@silver (BaTiO3 @Ag, BT@Ag) novel heterogeneous fiber via coaxial electrospinning followed by calcination technology, to simultaneously improve the dielectric property and breakdown strength ( E b ) of poly(vinylidene fluoride) (PVDF)-based composites. Dielectric measurement reveals that PVDF/BT@Ag composites have an enhanced e ˊ , low dielectric loss (tan δ) and moderately increased E b . Since the core-shell structured fibers help in tailoring the local electric field around the interface, but also provide double interfacial polarization, which effectively improves the dielectric properties of the composites. When the loading of BT@Ag reached up to 10 wt%, the e ˊ increased to 19.4 @1 kHz while the E b had maximum value of 389.1 MV/m, finally resulting in an improvement of U e . Moreover, the incorporation of BT@Ag obviously improves the mechanical properties of composites. It is expected that these results would further inspire the design of fillers with novel architecture for high-performance dielectric polymer composites.