Actuation behavior of PDMS dielectric elastomer composites containing optimized graphene oxide

Abstract

Actuation behavior of polydimethylsiloxane composites containing conductive fillers is of great interest but faces challenges such as increased elastic modulus and dielectric loss. In this work, thermal reduction of graphene oxide (GO) was utilized as an alternative to chemical modification in order to optimize dielectric properties and enhance actuation strain of the composites containing reduced graphene oxides (rGOs) near percolation threshold. During thermal reduction, the ratio of carbon to oxygen on the surface of rGOs was systematically altered in order to design particles with different surface properties. Dielectric behavior of composites containing rGOs prepared at four reduction temperatures (150 °C, 200 °C, 300 °C, and 400 °C) and employed at three volume fractions (0.25%, 0.5%, and 1%) was measured. The optimized condition for maximum dielectric permittivity and minimum dielectric loss was introduced as 0.52 vol% rGO reduced at 283 °C. The optimized condition was verified by measuring planar actuation strain and comparing with theoretical results. It was discussed that for dielectric elastomer composites containing conductive fillers near electrical percolation threshold, optimization based on dielectric properties provides better results than predictions based on the electromechanical sensitivity.