Core-shell structured CaCO3@CNF for enhanced dielectric properties of polymer nanocomposites

Polymer composites filled with conductive particles for high dielectric constant (high-κ) have been extensively studied due to their distinct advantages such as good processability, flexibility and lightweight. However, to achieve high dielectric constant usually requires high loadings of filler, which may bring conductivity leading to large dielectric loss. Here, insulative CaCO₃ is uniformly coated on the surfaces of carbon nanofibers (CNFs) via a facile self-assembly route, resulting in a core-shell structured CaCO₃@CNF. Blending it with epoxy resin shows an obvious enhancement in dielectric constant to neat epoxy resin due to the presence of 2.1 wt% CNFs in composite. Importantly, uniform dispersion of the core-shell structure with about 80 nm insulating shell can effectively block electron current. Then reduced dielectric loss and enhanced dielectric constant could occur simultaneously, which is significantly positive to the composites for further electric energy storage.