Suspending microscale droplets of liquid metals like
eutectic gallium–indium
(EGaIn) in polydimethylsiloxane (PDMS) has been shown to dramatically
enhance electrical permittivity without sacrificing the elasticity
of the host PDMS matrix. However, increasing the dielectric constant
of EGaIn–PDMS composites beyond previously reported values
requires high EGaIn loading fractions (>50% by volume) that can
result
in substantial increases in density and loss of material integrity.
In this work, we enhance permittivity without further increasing EGaIn
loading by incorporating polydopamine (PDA)-coated graphene oxide
(GO) and partially reduced GO. In particular, we show that the combination
of EGaIn and PDA-GO within a PDMS matrix results in an elastomer composite
with a high dielectric constant (∼10–57), a low dissipation
factor (∼0.01), and rubber-like compliance and elasticity.