Fabrication, Dielectric Mechanism, and Actuated Performance of Onion‐Like Carbons ( <scp>OLCs</scp> )/Silicone Rubber Flexible Dielectric Elastomer Nanocomposites

ABSTRACT Silicone rubber (SR) exhibits promising applications in flexible electronics owing to its flexibility, thermal stability, and electrical insulation. However, its inherent low dielectric constant (< 3.0) restricts application in advanced dielectric elastomers. To address this issue, onion‐like carbons (OLCs) with concentric graphitic shells and high electrical conductivity were strategically introduced as functional nanofillers to fabricate OLCs/SR dielectric elastomer nanocomposites. Results show that OLCs are homogeneously dispersed within the SR matrix. At 2 wt% OLC loading, the nanocomposite exhibited a notable dielectric constant of 5.82 (10 3 Hz) with an ultra‐low loss tangent of 0.00137, which can be attributed to interfacial polarization and well explained by the micro‐capacitor model. Meanwhile, this composite achieves optimal mechanical characteristics, including tensile strength of 236 kPa, elongation at break of 876%, and elastic modulus of 121 kPa. Importantly, it delivers a maximum actuated strain of 15.9% at a low electric field of 32 kV/mm, higher than that of pure SR (7.6%). Additionally, the nanocomposites maintain thermal stability above 400°C and no obvious change in electrical conductivity, though the breakdown strength decreases slightly. This integration of high dielectric constant, low loss tangent, favorable mechanical compliance, and excellent low‐field actuated strain makes the OLCs/SR nanocomposites promising for advanced flexible dielectric elastomer applications.