Effect of surface modification on the dielectric properties of PEN nanocomposites based on double-layer core/shell-structured BaTiO3 nanoparticles

► BaTiO3 nanoparticles were surface amine-functionalized and then grafted. ► The effect on the morphologies, interfacial and dielectric properties were investigated. ► The dielectric properties were measured as a function of both frequency and temperature. ► The inherent mechanism of temperature dependences of dielectric properties was clarified.