Due to some useful
mechanical, dynamic, and dielectric properties
along with the ease of processing and forming, liquid rubbers are
ideal materials for fabricating dielectric elastomer actuators in
various configurations and for many potential applications ranging
from automation to automobile and medical industry. In this study,
we present a cross-linkable liquid rubber composition where amine-catalyzed
esterification reactions lead to the formation of a network structure
based on anhydride functional isoprene rubber, carboxyl-terminated
nitrile-butadiene rubber, and epoxy end-capped prepolymers. The success
of this intricate network formation procedure was verified by HR-MAS
NMR spectroscopy. The new isoprene-based elastomeric material exhibits
actuation-relevant attributes including a low elastic modulus of 0.45
MPa, soft response to an applied load up to a large deformation of
300%, and a dielectric constant value (2.6) higher than the conventional
Elastosil silicone (2.2). A dot actuator comprising of an isoprene
dielectric elastomer film in unstretched state and carbon paste electrodes
was fabricated that demonstrated an electrode deformation of 0.63%,
which is nearly twice as high as for the commercial Elastosil 2030
film (∼0.30%) at 5 kV. Compared to the Elastosil silicone film,
the enhanced performance is attributed to the low modulus and high
dielectric constant value of the new isoprene elastomer.