Preparation, surface and dielectric properties of copper calcium titanate/ fluoro-containing polymer composite films

In order to improve dielectric properties of fluoropolymers, a emulsion based on a block copolymer composed of perfluorohexylethyl acrylate-stearyl acrylate random copolymer segment and glycidyl methacrylate-methyl acrylate random copolymer segment was synthesized by iodine transfer miniemulsion polymerization process, and compounded with copper calcium titanate (CCTO) to prepare composite films. The structure and properties of the copolymer and composite films were characterized by GPC, IR, SEM and dielectric impedance spectrometer. Results show that the composite films exhibit a bi-layer structure composed of a CCTO-riched layer and a polymer-riched layer. The composite film with 6 vol% CCTO exhibits a dielectric constant of 34 at 100 Hz, and good surface hydrophobic and oleophobic properties (static contact angles of water and n-hexadecane are 107.5° and 57.2°, respectively). The dielectric constant of the composite films at 100 Hz is increased to 85 when 6 vol% of CCTO surface modified with fluorinated-silane coupling agent is used. This is attributed to the improvement of the phase interface action caused by the "fluorine-fluorine" interaction. The above results provide a new idea for the design of high-dielectric constant composites at low-frequencies.