Core‐shell structured poly(glycidyl methacrylate)/BaTiO₃ nanocomposites prepared by surface‐initiated atom transfer radical polymerization: A novel material for high energy density dielectric storage

Core‐shell structured barium titanate‐poly(glycidyl methacrylate) (BaTiO 3 ‐PGMA) nanocomposites were prepared by surface‐initiated atom transfer radical polymerization of GMA from the surface of BaTiO 3 nanoparticles. Fourier transform infrared spectroscopy confirmed the grafting of the PGMA shell on the surface of the BaTiO 3 nanoparticles cores. Transmission Electron Microscopy results revealed that BaTiO 3 nanoparticles are covered by thin brushes (∼20 nm) of PGMA forming a core‐shell structure and thermogravimetric analysis results showed that the grafted BaTiO 3 ‐PGMA nanoparticles consist of ∼13.7% PGMA by weight. Upon incorporating these grafted nanoparticles into 20 μm‐thick films, the resultant BaTiO 3 ‐PGMA nanocomposites have shown an improved dielectric constant ( ε = 54), a high breakdown field strength (∼3 MV/cm) and high‐energy storage density ∼21.51 J/cm 3 . AC conductivity measurements were in good agreement with Jonscher's universal power law and low leakage current behavior was observed before the electrical breakdown field of the films. Improved dielectric and electrical properties of core‐shell structured BaTiO 3 ‐PGMA nanocomposite were attributed to good nanoparticle dispersion and enhanced interfacial polarization. Furthermore, only the surface grafted BaTiO 3 yielded homogenous films that were mechanically stable.