Core-shell like structured barium zirconium titanate-barium calcium titanate-poly(methyl methacrylate) [(Ba0.94Ca0.06)(Zr0.16Ti0.84) O-3-PMMA] nanocomposites were prepared by surface-initiated atom transfer radical polymerization (SI-ATRP) of methyl methacrylate (MMA) from the surface of BZT-BCT nanoparticles. X-ray diffraction patterns of pure polymer and BZT-BCT nanoparticles revealed their amorphous and polycrystalline natures respectively. Fourier transform infrared spectroscopy confirmed the grafting of the PMMA shell on the surface of the BZT-BCT nanoparticles cores. Transmission electron microscopy (TEM) results revealed that BZT-BCT nanoparticles were covered by a very thin layer of PMMA forming a core-shell like structure and thermogravimetric analysis results showed that the grafted BZT-BCT-PMMA nanoparticles consist of similar to 80.1% PMMA by weight. Polymer grafted BZT-BCT nanocomposite thick films (similar to 10 mu m) have shown an improved dielectric constant (epsilon similar to 56), a high breakdown field strength (similar to 3 MV/cm) and high-energy storage density similar to 22.5 J/cm(3). The improved electrical properties of core-shell like structured BZT-BCT-PMMA nanocomposites were attributed to improved nanoparticle dispersion and enhanced interfacial polarization due to the covalent linkage between polymer and nanoparticle interface. Mechanically stable and homogeneous composite films were obtained using the surface grafted BZT-BCT ceramic nanoparticles. (C) 2016 Elsevier Ltd. All rights reserved.