Fabrication, structure, and property of epoxy-based composites with metal–insulator core–shell structure fillers

The Ag@SiO2core-shell structure nanoparticles prepared by chemical method were dispersed into epoxy matrix. By comparing with the epoxy-based composites filled with the mixed Ag and SiO2nanoparticles (Ag + SiO2), it is found that the Ag@SiO2core-shell structure fillers had important effects on the improved dielectric properties of the Ag@SiO2/epoxy composites. The core-shell structure fillers introduce a duplex interfacial polarization and a small number of free charge carriers, which enhance the dielectric permittivity of the composites. At the same time, the insulating SiO2shell layer changes the interfacial interaction between the Ag filler and the epoxy matrix, not only avoiding Ag particles to connect directly and aggregate together but also providing a rough surface to contact with the epoxy host, which enhances the compatibility between the Ag@SiO2fillers and the epoxy matrix. As the Ag@SiO2packing ratio increases, the permittivity of the composites straightly increases and the loss tangent decreases, reaching the maximum and minimum respectively with the filler loading up to 60%.