Enhancing dielectric properties of ceramic-polymer composites by rationally constructing of a 3D-BaTiO3 network

The conventional melt-mixing process for preparing ceramic-polymer dielectric composites often requires a high filler loading and results in random dispersion of fillers, which leads to an extremely low efficiency in enhancing the dielectric constant (ε') and increases processing difficulty. Enhancing the dielectric properties of composites materials at low filler contents has remained a significant challenge. In this study, silane coupling agent was selected as the bridging agent, its double bond end was copolymerized with polystyrene (PS) microspheres, and its silicon bond end was bonded with hydroxyl dehydration on the surface of ferroelectric barium titanate (BT) ceramics, so that BT particles were firmly riveted on the surface of PS microspheres (PS@BT). Then the composites with a three-dimensional (3D) segregated structure were obtained through hot-pressing PS@BT microspheres. The effects of the 3D BT network structure and its content on the dielectric properties of the composites were investigated. The results indicated that when the content of BT was only 13.7 vol%, the ε' of the composites reached 9.7 (100 kHz), significantly higher than that of the traditional randomly mixed PS/BT composites, while the dielectric loss (tanδ) remaining basically unchanged, which are significantly superior to those of composites prepared by conventional melt-blending. This method can provide guidance for the fabrication of high-performance dielectric composites.