Electromechanical performance of polydimethylsiloxane containing reduced graphene oxide grafted by long-chain alkyl sila
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Electromechanical performance of polydimethylsiloxane containing reduced graphene oxide grafted by long-chain alkyl silane Mohsen Sadroddini1 1
and Mehdi Razzaghi-Kashani1,*
Polymer Engineering Department, Faculty of Chemical Engineering, Tarbiat Modares University, P.O. Box 14115-114, Tehran, Islamic Republic of Iran
Received: 26 April 2020
ABSTRACT
Accepted: 4 September 2020
The present study investigates the effects of grafting a long-chain organosilane (OS) onto the reduced graphene oxide (rGO) on dielectric and electromechanical performance of polydimethylsiloxane (PDMS). Accordingly, two types of OSrGO particles were synthesized with different grafting densities and characterized by various tests such as Fourier transform infrared spectroscopy, Raman spectroscopy, and thermo-gravimetric analyses. As-prepared particles were introduced into PDMS using the solution mixing method to manufacture composites with different concentrations of particles. Dielectric results revealed that the composites containing OS-rGO particles offer better dielectric performance in terms of higher ‘‘dielectric efficiency’’ and dielectric breakdown strength than composites containing rGO or neat PDMS. The higher the grafting density of OS, the better the dielectric and electromechanical performance is obtained. By examining the electrical conductivity of particles, it was discussed that the spacer length of silane creates a space-filling insulating layer around the conductive rGO particles, traps free electric charges at the particle-polymer interface, postpones the electrical percolation threshold to higher concentrations, and reduces the dielectric loss through suppressing the leakage current of charges in the composite. Actuation strain of PDMS containing 3 wt% of OSrGO with high grafting density was almost twice that for the neat PDMS.
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Springer Science+Business
Media, LLC, part of Springer Nature 2020
1 Introduction Electroactive polymers (EAPs), as a category of smart polymers, are known as transducers for electrical stimulation to mechanical deformation [1]. Dielectric elastomer actuators (DEAs), as one of the important
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https://doi.org/10.1007/s10854-020-04423-2
subgroups of EAPs, offer significant capabilities in various applications such as artificial muscles and microactuators [2]. From the dielectric point of view, the high dielectric permittivity is one of the primary requirements in DEAs. Including fillers is one of the ways to enhance
J Mater Sci: Mater Electron
the dielectric permittivity of polymers using (I) ceramics with high dielectric permittivity and (II) electrically conductive carbon derivatives [3]. Electrically conductive particles provide advantages over ceramic particles in polymer composites such as high dielectric constant, low filler loading, good mechanical flexibility, and easy processing [4]. In the last decade, graphene has drawn the attention of researchers in the field of polymer composites due to its unique mechanical,
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