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Flexible dielectric polymer composites have been of great interest as embedded capacitor materials in the electronic industry. However, a polymer composite has a low relative dielectric permittivity (ε′ < 100), while its dielectric loss tangent is generally large (tanδ > 0.1). In this study, we fabricate a novel, high-permittivity polymer nanocomposite system with a low tanδ. The nanocomposite system comprises poly(vinylidene fluoride) (PVDF) co-filled with Au nanoparticles and semiconducting TiO2 nanorods (TNRs) that contain Ti3+ ions. To homogeneously disperse the conductive Au phase, the TNR surface was decorated with Au-NPs ~10–20 nm in size (Au-TNRs) using a modified Turkevich method. The polar β-PVDF phase was enhanced by the incorporation of the Au nanoparticles, partially contributing to the enhanced ε′ value. The introduction of the Au-TNRs in the PVDF matrix provided three-phase Au-TNR/PVDF nanocomposites with excellent dielectric properties (i.e., high ε′ ≈ 157 and low tanδ ≈ 0.05 at 1.8 vol% of Au and 47.4 vol% of TNRs). The ε′ of the three-phase Au-TNR/PVDF composite is ~2.4-times higher than that of the two-phase TNR/PVDF composite, clearly highlighting the primary contribution of the Au nanoparticles at similar filler loadings. The volume fraction dependence of ε′ is in close agreement with the effective medium percolation theory model. The significant enhancement in ε′ was primarily caused by interfacial polarization at the PVDF–conducting Au nanoparticle and PVDF–semiconducting TNR interfaces, as well as by the induced β-PVDF phase. A low tanδ was achieved due to the inhibited conducting pathway formed by direct Au nanoparticle contact.

In this work, nanocomposites consisting of TiO 2 -nanorods (TiO 2 -NRs) with less than 100 nm in size and poly(vinylidene fluoride) (PVDF) were prepared using a liquid-phase assisted dispersion and hot-pressing methods. At 1 kHz and 25 C, the high dielectric permittivity of $66 and loss tangent of $0.03 can be obtained in the nanocomposite with a filler volume fraction of 0.5, which was higher than that of a neat PVDF matrix by a factor of 6. Dielectric permittivity of TiO 2 -NRs/PVDF nanocomposites not only highly increased with TiO 2 -NRs, but also almost independent of the frequency range of 10 2 -10 6 Hz. The significant enhancement in dielectric permittivity is mainly attributed to the interfacial polarization at the interfaces of TiO 2 -NRs and PVDF, and semiconducting properties of TiO 2 -NRs. Among the various models used for rationalizing the dielectric behavior, the experimental dielectric data is in close agreement with EMT (n ¼ 0.11) and Yamada models (n ¼ 8).

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Greatly enhanced dielectric permittivity (e 0 ) in poly(vinylidene fluoride) (PVDF) polymeric composites was induced by incorporating Na 1/3 Ca 1/3 Bi 1/3 Cu 3 Ti 4 O 12 (NCB) nanoparticles. The NCB/PVDF composites were fabricated by conventional mixed powders and hot pressing. Nanosized (NCB-NPs) and microsized-powders (NCB-MPs) prepared, respectively, by chemical combustion and solid state reaction methods were used as fillers. The dispersion of NCB-NPs was quite good in the PVDF matric. A greatly improved e 0 of PVDF-based polymeric composites can be induced by filling with NCB-NPs compared to that of the NCB-MPs/PVDF composite. Interestingly, at 10 3 Hz, the nanocomposite with 50 vol% of NCB-NPs can exhibit good dielectric properties with high e 0 of about 210.8 and low loss tangent (tand & 0.83). This enhanced e 0 value is much larger than that of PVDF polymer by a factor of &20. The increase in e 0 in the nanocomposites is attributed to large interfacial areas and very short interparticle distance. These can cause a great increase in the interfacial polarization intensity.

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