A rational design of core-shell-satellite structured BaTiO3 fillers for epoxy-based composites with enhanced microwave dielectric constant and low loss

Abstract With the rapid progress of wireless communication technology, development of composites with high dielectric constant (high-k) and low loss at gigahertz frequency calls for novel materials design strategies. Core-shell-satellite structured BaTiO3 (BT) nanoparticles with polydopamine (PDA) layers and silver (Ag) nanoparticles were herein developed, which were incorporated into epoxy (EP) to prepare a set of composites. Physicochemical properties of modified BT nanoparticles and the dispersion and interface of corresponding modified BT/EP composites were comparatively investigated. The dielectric properties of modified BT/epoxy (EP) nanocomposites with various filler fractions were investigated at 8–12 GHz. It is found that, at the highest filler volume fraction (20 vol%), the dielectric constant of BT-PDA-Ag/EP at 10 GHz reached 8.4, and the loss tangent was also suppressed at 0.024. The polarization and loss mechanisms of the composites were then proposed based on the morphologies and the microstructures of the composites. BT-PDA-Ag promotes interfacial polarization, better dispersion and reduced mismatch, resulting in enhanced dielectric constant and low loss. More importantly, by ensuring a disconnection of the silver particles, PDA hinders the formation of conductive network thus suppressing the dielectric loss. This research provides a novel strategy to prepare high-k and suppressed loss nanocomposites potentially for 5G applications.