Abstract
A new functionalised graphene sheet (FGS) filled poly(dimethyl)siloxane insulator nanocomposite has been developed with high dielectric constant, making it well suited for applications in flexible electronics. The dielectric permittivity increased tenfold at 10 Hz and 2 wt.% FGS, while preserving low dielectric losses and good mechanical properties. The presence of functional groups on the graphene sheet surface improved the compatibility nanofiller/polymer at the interface, reducing the polarisation process. This study demonstrates that functionalised graphene sheets are ideal nanofillers for the development of new polymer composites with high dielectric constant values.PACS: 78.20.Ci, 72.80.Tm, 62.23.Kn
Highlights
In recent years, elastomeric materials with high dielectric constant have been considered for different functional applications such as artificial muscles, high charge-storage capacitors and high-K gate dielectric for flexible electronics [1,2]
The electronic charge for composites up to 1.0 wt.% of CNT remained confined on isolated carbon nanotubes by the insulating polymer matrix
The large increase in the loss tangent as a function of the frequency shows the existence of a strong interfacial polarisation phenomenon, clearly indicating that CNT/ PDMS composites are percolative systems with a critical weight fraction between 1.0 and 2.0 wt.% of CNT
Summary
Elastomeric materials with high dielectric constant have been considered for different functional applications such as artificial muscles, high charge-storage capacitors and high-K gate dielectric for flexible electronics [1,2]. Dielectric constant increments have been met with relatively high loss tangent values (tg (δ)) and frequency dependence which is undesirable for capacitor applications [6,7] Obtaining composites with both high dielectric permittivity and low loss tangent values at the same time is specially challenging due the interfacial polarisation or MaxwellWagner-Sillars (MWS) process. Rapid heating (30 s at 1,000°C) of the graphite oxide under inert atmosphere produced the partial thermal decomposition of the functional groups (epoxy, hydroxyl and carboxyl groups) present in the GO, splitting the GO into FGS through the evolution of CO2 (gas). Both CNT and FGS were used without further treatments. Samples were sputter-coated with a thin layer of 3 to 4 nm of gold/palladium lead prior to imaging
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