Influence of shell thickness on the dielectric properties of composites filled with Ag@SiO2 nanoparticles

Flexible polymer composites were fabricated by a solution casting method with core-shell structure nanoparticles (Ag cores coated by SiO2 shell). Ag@SiO2 nanoparticles were prepared by a simple Stober method. The transmission electron microscopy micrographs indicated that the Ag nanoparticles were about 40-55 nm in diameter and the thickness of the shell was 5-20 nm. Compared to the pure PVDF-TrFE, the composites exhibited enhanced dielectric constants and lower dielectric loss. Additionally, an improved breakdown field of the composites was obtained when the filler content was 10 wt% with the SiO2 shell thickness of 10 and 20 nm. Furthermore, the effect of shell thickness was investigated and the results showed that dielectric constant and breakdown field increased with increasing shell thickness. The improved dielectric performance suggests a promising way to fabricate composites for potential applications in electronic devices.