Dielectric Elastomers with a High Dielectric Constant and Low Loss for Advanced Soft Actuators and Sensors

Dielectric elastomers (DEs) show great potential in flexible actuation and strain sensing, but their performance is often limited by the coupling between low dielectric constant and high Young’s modulus, resulting in high driving fields and weak sensing signals. In this work, we propose a molecular design strategy that combines polarity enhancement with crosslinked network regulation. Using urethane diacrylate (CN9021NS) as the matrix, a highly polar -CF3 containing monomer, hexafluorobutyl acrylate (HFBA), is introduced to enhance the dielectric constant. Poly(ethylene glycol) diacrylate (PEGDA) with different chain lengths serves as a small-molecule crosslinker to regulate the network structure. By varying the PEGDA chain length and content, the influence of crosslinker molecular architecture on effective network constraints and chain mobility is systematically investigated. The results show that CHBP10-3 with long-chain crosslinkers achieves a high dielectric constant (7.42@1 kHz), a low Young’s modulus (0.28 MPa), reduced mechanical loss (6.33%), and high stress retention. In electromechanical actuation, the material exhibits a large area strain of 161.73% at 40 kV mm–1. Based on these properties, the CHBP10-3 actuator enables large-angle bending, effective load driving, and serves successfully as a soft gripper. Meanwhile, the CHBP10-3-based sensor shows stable capacitive responses over a wide strain range, allowing applications in human motion monitoring and information encoding. This work offers a simple strategy for crosslinked network regulation and new insights into high-performance dielectric elastomers.