A Dielectric Elastomer Containing Bicomponent Core–Shell Nanoparticles with Enhanced Electromechanical Properties for Flexible Crawling Robots

Dielectric elastomer actuators (DEAs) with reversible large electrically actuated strains can be used to build lightweight and flexible crawling robots. Silicone rubber (SR) has become a research hotspot for dielectric elastomer (DE) materials due to its stable performance and fast response speed (ms), but it has the problems of a small actuation strain, a low dielectric constant, and a large driving electric field, which seriously limit the actuation performance of DEAs. To solve this problem, in this paper, carbon dots (CDs) were grafted onto BaTiO(C2O4)2@urea (BTRU) core–shell nanoparticles to successfully synthesize BaTiO(C2O4)2@urea/CDs (BTRU/CDs) nanoparticles with a bicomponent shell structure. These bicomponent shell structure nanoparticles were added as a filler phase to plasticized SR to obtain BTRU/CDs/SR composite films with enhanced mechanical and dielectric properties. For the 15 wt % BTRU/CDs/SR elastomer simultaneously exhibiting an ideal modulus (∼0.193 MPa), a high toughness (elongation ∼849.5%), and satisfactory dielectric properties (εr = 6.91@1 Hz), accordingly, the out-of-plane actuation displacement can reach 3.28 mm (10 kV/mm@1 Hz), which is 683% higher than the pure matrix. Compared with VHB 4910, the area strain rate (42.4%@22 kV/mm) and average crawling speed (10 mm/s, 3 kV@8 Hz) of DEA and a flexible crawling robot prepared based on our elastomer are 4.4 times and 1.3 times higher, respectively. These valuable findings may provide a strategy for preparing high-performance DEs for applications in the field of flexible actuators or flexible robots.