High-k zwitterionic dielectric elastomers with internal plasticization for low-voltage actuation

Abstract

High dielectric constant (high-k) elastomers have been the focus of numerous studies, particularly for the low-voltage operation of dielectric elastomer actuators (DEAs). However, existing methods to achieve both mechanical softness and high-k properties have been dependent on external additives, such as solvents or conductive species, which limit the efficient charge accumulation on the dielectric surfaces at high voltage. We synthesized high-k zwitterionic dielectric elastomers by copolymerizing a zwitterionic monomer with a low glass transition temperature (Tg) monomer. The low Tg comonomer, which serves as an internal plasticizer, facilitates the orientation polarization of zwitterion side chains. The resulting dielectric elastomer exhibits both a significantly elevated dielectric constant (49.6 @ 10 Hz) and high compliance (2.6 MPa⁻¹) at room temperature compared to pure zwitterionic polymers. Its exceptional electromechanical sensitivity enables an unprecedented low-field DEA operation, demonstrating 100 % areal strain using only household electricity (220 V_AC, ∼11.4 V/μm). This work proposes a simple intramolecular approach for designing novel high-k soft dielectrics that can be widely adopted for various polar polymers.