electric fi elds (above 50 V mm − 1 ), which poses the greatest obstacle to their practical application.When an electric fi eld is applied across a fi lm thickness, a fi lm of electrostrictive materials is compressed in the longitudinal direction, and spreads in the lateral planar direction. Unlike piezoelectricity, which has a linear relationship with applied fi eld, this electrostriction behavior demonstrates that the total thickness strain, s z has a quadratic relationship with the applied electric fi eld ( E ), as delineated by the following equation:where R 33 represents the sensitivity of the strain response of a material to the applied electric fi eld.In general, the electric actuation of dielectric elastomers is driven by the two mechanisms of Maxwell stress and a true electrostrictive effect, as illustrated in Figure 1 . [ 13 , 14 ] The electrostriction of a dielectric elastomer is usually dominated by Maxwell stress, which is caused by the Coulomb interaction between oppositely charged compliant electrodes, expressed as Equation 2 . Electric Actuation of Nanostructured Thermoplastic Elastomer Gels with Ultralarge Electrostriction Coeffi cientsElectrostriction facilitates the electric fi eld-stimulated mechanical actuation of dielectric materials. This work demonstrates that introduction of dielectric mismatched nanodomains to a dielectric elastomer results in an unexpected ultralarge electrostriction coeffi cient, enabling a large electromechanical strain response at a low electric fi eld. This strong electrostrictive effect is attributed to the development of an inhomogeneous electric fi eld across the fi lm thickness due to the high density of interfaces between dielectric mismatched periodic nanoscale domains. The periodic nanostructure of the nanostructured gel also makes it possible to measure the true electromechanical strain from the dimensional change monitored via in situ synchrotron small angle X-ray scattering. The work offers a promising pathway to design novel high performance dielectric elastomers as well as to understand the underlying operational mechanism of nanostructured multiphase electrostrictive systems.

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Silicone elastomer actuators were investigated to develop a simple and industrially scalable product with improved mechanical properties, such as a low modulus, high tearing strength, and good resilience, and enhanced electromechanical actuation properties. Silicone elastomers were fabricated via a hydrosilylation addition reaction with a vinyl-end-functionalized poly(dimethyl siloxane) (V), a multivinyl-functionalized silicone resin, and a crosslinker in the presence of a platinum catalyst. For the larger electromechanical actuation response, the silicone dielectric elastomer actuator had to have a larger molecular weight of poly(dimethyl siloxane), a smaller hardener content, and a resin-free composition. However, the silicone elastomer actuators needed to include a small amount of resin to improve the tearing strength. V C 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40030.

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