Large-scale production of oxidation-resistant Cu@SiO2 core-shell nanoparticles for dielectric applications

In this study, we report the large-scale fabrication of Cu@SiO₂ nanoparticles with core-shell structure using a modified Stöber method. The obtained nanoparticles had an average particle size of 300 nm with SiO₂ shell about 20 nm and exhibited excellent oxidation resistance and thermal stability in air atmosphere. PVDF based nanocomposites filled with pure Cu and Cu@SiO₂ nanoparticles have been prepared by hot press method and their dielectric behavior was investigated. Compared with the Cu/PVDF composite, no typical percolation effect was observed in the Cu@SiO₂/PVDF composite and when the content of Cu@SiO₂ filler reached 20 vol %, the composite exhibited a high dielectric constant of 100 while maintained a low loss value of 0.1 at 1 kHz. Based on their excellent dielectric properties, core-shell Cu@SiO₂ NPs are expected to be ideal fillers to develop polymer-based composites with high dielectric constant and low dielectric loss.