Silica-decorated reduced graphene oxide (SiO2@rGO) as hybrid fillers for enhanced dielectric and actuation behavior of polydimethylsiloxane composites

Abstract

A novel high performance dielectric elastomer actuator with a high dielectric constant, low dielectric loss, high dielectric breakdown strength and large actuated strain was prepared through introducing hybrid fillers of chemically reduced graphene oxide (rGO) covered by a SiO2 shell (SiO2@rGO). Hybrid particles were synthesized with two different shell coverage using tetraethylorthosilicate (TEOS) and characterized with different methods to identify the surface chemistry, inter-layer spacing, and thickness of the platelets as SiO2 shells were introduced and reduction process was applied. Composites of polydimethylsiloxane (PDMS) containing different amounts of rGO and SiO2@rGO particles were prepared by the solution mixing method. The results showed that composites with hybrid fillers have higher dielectric efficiency and dielectric strength than rGO/PDMS composites. However, higher actuated strains than the pure PDMS was obtained only with hybrid particles with dense coverage. Maximum actuated strain increased from 4.63% for the pure PDMS to 12.83% and 9.12% for composites with 1 wt% and 2 wt% of SiO2@rGO with denser SiO2 shell, respectively. Results suggest the positive effect of hybrid graphenic structures with high shell coverage and certain weight fraction toward preparing high performance dielectric elastomer actuator composites.