Plasticizer-modulated low-voltage dielectric elastomer actuator with superior electromechanical properties

Dielectric elastomer actuators (DEAs) are characterized by large actuation strain, fast response, and high energy conversion efficiency, and hence are promising for bioinspired soft robotics. However, current DEAs typically require high driving electric fields due to their low dielectric constant and high Young's modulus. Herein, we propose a versatile strategy that incorporates a small-molecule plasticizer, dioctyl phthalate (DOP), into a dielectric elastomer network to develop plasticized DEAs with a high electromechanical sensitivity coefficient (207.6 MPa −1 ) and an extremely low driving electric field threshold of 1.8 V/μm. The developed DEAs demonstrate an unprecedented area actuation strain of 60% at 40 V/μm, and exhibit a unique electrode polarity-dependent actuation behavior. Furthermore, the actuation mechanisms are elucidated by macroscopic mechanical tests, confocal Raman spectroscopy, and molecular dynamics simulations, revealing that the migration of DOP plasticizer molecules in the matrix, which creates a gradient in dielectric and mechanical properties, is the key factor for achieving superior actuation performance at a low driving electric field. Finally, a cylinder-like DEA is fabricated to demonstrate its application potential in the field of artificial muscles. This work provides a simple and easy method for designing low driving voltage DEAs with high electromechanical performance.