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Abstract

Recent efforts have established that thermoplastic elastomer gels (TPEGs) composed of styrenic triblock copolymers swollen with a midblock-selective solvent exhibit remarkable electromechanical properties as high-performance dielectric elastomers. This class of electroactive polymers typically requires high electric fields for actuation, and a shortcoming that continues to thwart the widespread commercialization of such materials in general is the need to apply mechanical prestrain prior to electroactuation to decrease film thickness and, thus, the electric potential required to promote actuation. To alleviate this requirement, TPEGs consisting of acrylic triblock copolymers differing in molecular weight and composition, and swollen with a high dielectric, midblock-selective solvent are investigated. Synchrotron small-angle x-ray scattering is used to probe the nanoscale morphologies of the resultant materials, and analysis of quasi-static and cyclic tensile properties provides additional insight into both blend morphologies and electroactuation efficacy. Actuation strains measured in the absence of mechanical prestrain exceed 100% on an area basis, and electric fields capable of inducing actuation are as low as ∼20 kV/mm. Failure occurs by either electromechanical instability or dielectric breakdown, depending on the copolymer and TPEG composition employed. The electromechanical properties of these acrylic-based TPEGs match or exceed those of skeletal muscle, in which case they constitute an attractive and unexplored alternative to existing dielectric elastomers.