High-Performance Block-Copolymer-Based Dielectric Elastomers with Enhanced Mechanical Properties

Thermoplastic elastomer gels have been highlighted in recent years due to their highly tunable properties, becoming interesting electroactive polymers for the fabrication of dielectric elastomer actuators. These materials are obtained by adding high concentrations of an organic solvent, such as mineral oil, to a block copolymer thermoplastic elastomer. The organic solvent is selective to one of the blocks and, therefore, significantly improves the elastomer flexibility. However, high solvent concentrations tend to reduce the mechanical stability of these materials, restricting future applications. In this work, we aimed to improve the strength and elongation of polystyrene-b-poly(ethylene-butylene)-b-polystyrene (SEBS) block copolymer gels by partially substituting mineral oil for a hydrogenated hydrocarbon resin, which has partial miscibility with the rubbery central block. The addition of the resin led to a significant increase in tensile strength and elongation at break (1000 and 1300%, respectively), compared to the thermoplastic elastomer gels containing solely mineral oil and without a significant increase in elastic modulus. The resulting gels show promise for electroactive applications, exhibiting a remarkable mechanical response to an electrical stimulus. The materials also demonstrate large actuation strains under relatively low electric fields, showing superior performance compared to other systems in the literature.