Dielectric properties of polystyrene based composites filled with core-shell BaTiO3/polystyrene hybrid nanoparticles

In this work, core-shell structured BaTiO ₃ /polystyrene nanoparticles (BT-PS) with different thickness of PS shell were synthesized through atom transfer radical polymerization and the influence of their shell thickness on dielectric properties of BT-PS/PS composites was studied. Two types of BT-PS with the PS shell of 3 nm or 12 nm were obtained by controlling the polymerization time. The structure of BT-PS was carefully characterized by infrared spectroscopy, X-ray diffraction, thermal gravimetric analysis, and transmission electron microscope. The results confirmed the successful preparation of core-shell BT-PS nanoparticles. Compared to pristine BT, the core-shell particles can be more homogeneously dispersed into PS matrix. As a result, higher dielectric constant, higher breakdown strength, and lower dielectric loss were achieved in BT-PS/PS composites. Moreover, the dielectric constant of BT-PS/PS composites displayed frequency independent behavior. In addition, the composites filled by BT-PS with 3 nm of PS shell showed better dielectric properties than those filled by BT-PS with 12 nm of PS shell. A maximum energy density as large as 4.24 J/cm ³ was obtained in BT-PS/PS films.