Preparation and dielectric properties of core–shell structural composites of poly(1H,1H,2H,2H-perfluorooctyl methacrylate)@BaTiO3 nanoparticles

Polymer nanocomposite films, poly(1H,1H,2H,2H-perfluorooctyl methacrylate)@BaTiO3 (PPFOMA@BaTiO3), with enhanced dielectric permittivity was fabricated via a two-step processes, consisting of BaTiO3 nanoparticle surface modification and surface initiated atom transfer radical grafting polymerization (SI-ATRP). At first, BaTiO3 nanoparticles were treated by hydroxylation, silylation and amidation to offer their SI-ATRP capability. Then PPFOMA chains were grafted from the modified BaTiO3 nanoparticles by SI-ATRP at 70 °C to form core–shell composites. The effects of polymer structure and polymer/BaTiO3 ratios on dielectric properties were measured over a broad frequency from 40 Hz to 30 MHz at room temperature. The results showed that the dielectric constant (k) increased and dielectric loss reduced significantly with the addition of BaTiO3. The k of the composite was up to 7.4 at 100 kHz at room temperature when the BaTiO3 loading was up to 70.70 wt% which is almost three time of pure PPFOMA (k = 2.6). While the dielectric loss (tan δ) of PPFOMA@BaTiO3 composite was about 0.01, which was much lower than that of the pure PPFOMA (tan δ = 0.04).