Enhancing dynamic actuation performance of dielectric elastomer actuators by tuning viscoelastic effects with polar crosslinking

Dielectric elastomer actuators (DEAs) have shown great potential in the field of robotics, energy harvesting, or haptics for wearables. However, existing DEA materials typically require prestretching and exhibit time-dependent deformations due to their inherent viscoelastic properties. In this work, we address these issues by designing and synthesizing a polyurethane acrylate (PUA) DEA copolymerized with a polar crosslinker, polyethylene glycol diacrylate (PEGDA), to reduce viscoelastic effects through chemical crosslinking. We realized a buckling-mode actuator that displays out-of-plane deformations triggered by an electric field without the need for prestretching. Copolymerization with PEGDA showed improved dynamic response actuation performances compared to pristine PUA, wherein the former reached 90% of its maximum actuation in <1 s. In addition, precise and stable actuation was achieved, reducing viscoelastic drifts to a negligible amount. Despite the higher elastic modulus of the DEA incurred by the chemical crosslinks, the polar groups present in the PEGDA comonomer effectively increased the dielectric constant. As such, a higher area strain was achieved in comparison to that exhibited by low viscoelastic elastomers such as silicone. By eliminating the need for prestretching, rigid components can be avoided, thereby enabling greater prospects for the integration of fast response and stable DEAs into soft bodies.