Large-Deformation Bimodal Network Dielectric Elastomer

Dielectric elastomers (DEs) are electroactive smart materials capable of significant reversible deformation under electric fields. Their muscle-like properties, including compliance, large strain, high energy density, and fast response, make them promising for artificial muscles and soft robotics. However, electromechanical instability (EMI) limits their practical application by preventing the simultaneous achievement of stability and large deformation. This study designed a dielectric elastomer with a bimodal network structure using cross-linkers of different chain lengths, solution processing, and UV curing. This created a network with long chains for extensibility and short chains to enhance modulus and suppress Maxwell stress instability, thus mitigating EMI. The resulting poly(2-ethylhexyl acrylate) (EHAP) elastomer film achieved 209% electrically induced strain, a two-order-of-magnitude increase in energy density, and a breakdown field strength of 88.5 V/μm. It maintained a low modulus, excellent cycling stability (100% strain retention after 2000 cycles at 2 Hz), and good response speed.