Silica-decorated reduced graphene oxide (SiO ₂ @rGO) as hybrid fillers for enhanced dielectric and actuation behavior of polydimethylsiloxane composites

Abstract

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 SiO 2 shell (SiO 2 @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 SiO 2 shells were introduced and reduction process was applied. Composites of polydimethylsiloxane (PDMS) containing different amounts of rGO and SiO 2 @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 SiO 2 @rGO with denser SiO 2 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.