High dielectric permittivity and suppressed loss tangent in PVDF polymer nanocomposites using gold nanoparticle-deposited BaTiO3 hybrid particles as fillers

A high dielectric permittivity (ε′) with a suppressed loss tangent (tanδ) can be obtained in poly(vinylidene fluoride) (PVDF) polymer nanocomposites using gold (Au)−deposited nano-BaTiO3 hybrid particles (Au-nBT) as fillers. Au-nBT hybrid particles were successfully prepared by a modified Turkevich method, while Au-nBT/PVDF nanocomposites were prepared using liquid-phase assisted dispersion and hot-pressing methods. Au nanoparticles with sizes of ≈10-30 nm were discretely grown on the nBT surface, which efficiently inhibited continuous contact between conductive Au nanoparticles and formation of conducting paths in the polymer matrix. This can cause suppression of conductivity and related tanδ values. Interestingly, ε′ of the Au-nBT/PVDF nanocomposites increased from 26.7 to 158.2 (at 1 kHz) with increased filler loadings from 4 to 62 vol%, while tanδ slightly increased from 0.034 to 0.055 with very low conductivities (σ < 10−9 S/cm). Greatly enhanced ε′ values that were slightly dependent on frequency in the range of 102−106 Hz are attributed to an enhanced local electric field strength, inducing stronger dipolar polarization in the Au-nBT/PVDF nanocomposites.