Enhanced dielectric properties of PVDF-HFP/BaTiO₃-nanowire composites induced by interfacial polarization and wire-shape

Polymer based composites with high dielectric constant were successfully fabricated using BaTiO₃ nanowires with high aspect ratio as inorganic filler and PVDF-HFP as polymer matrix. PVDF-HFP/BaTiO₃ nanoparticles composites were also prepared as a contrast. The BaTiO₃ nanowires were synthesized via one-step hydrothermal method. The BaTiO₃ nanowires and its two types of composites were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy and transmission electron microscopy. For the composites, breakdown strength measurements, tensile tests and broadband dielectric spectroscopy analyses were also carried out. The results show that the two types of fillers are homogeneously dispersed in the matrix. The dielectric constant of composites filled by BaTiO₃ nanowires is larger than that filled by BaTiO₃ nanoparticles at the same content. Stronger interfacial polarization was found in PVDF-HFP/BaTiO₃ nanowire composites. Two theoretical models were employed to predict the dielectric constants of composites, and the experimental data were consistent with the estimated trend. The enhanced dielectric properties of PVDF-HFP/BaTiO₃ nanowire composites are attributed to the superior interfacial polarization and high aspect ratio of BaTiO₃ nanowires.