Preparation and Dielectric Characterization of P(VDF-TrFE) Copolymer-Based Composites Containing Metal-Formate Frameworks

Abstract

We report the synthesis and dielectric characterization of novel polyvinylidene fluoride-trifluoroethylene P(VDF-TrFE) composite films containing [(CH₃)₂NH₂][Mg(HCOO)₃] (DMAMg) and [NH₄][Zn(HCOO)₃] (AmZn) dense metal-organic frameworks (MOFs). The optical camera and Raman microscopies are used to map the distribution of the MOF fillers in the prepared films. The dielectric spectroscopy experiments of the DMAMg/P(VDF-TrFE) composite performed in a broad temperature range demonstrate rich dielectric behavior originating from the dipolar dynamics of the (CH₃)₂NH₂⁺ molecular cations and glassy behavior of the copolymer matrix. An anomalous behavior of the complex dielectric permittivity is also observed because of the structural phase transition of DMAMg fillers. The dielectric properties of the AmZn/P(VDF-TrFE) composite film are mainly determined by the dipolar glass relaxation of the P(VDF-TrFE) polymer. The frequency-dependent dielectric spectra of both composites allow us to characterize the observed dipolar relaxation processes. The (CH₃)₂NH₂⁺ cation dynamics follows the Arrhenius law, whereas the glassy behavior of P(VDF-TrFE) is described by the Vogel-Fulcher equation. For both composites, we observe a significant increase of the dielectric permittivity compared with the P(VDF-TrFE) film without MOF fillers.