Elastomers with high dielectric permittivity that self‐heal after electric breakdown and mechanical damage are important in the emerging field of artificial muscles. Here, a one‐step process toward self‐healable, silicone‐based elastomers with large and tunable permittivity is reported. Anionic ring‐opening polymerization of cyanopropyl‐substituted cyclic siloxanes yields elastomers with polar side chains. The equilibrated product is composed of networks, linear chains, and cyclic compounds. The ratio between the components varies with temperature and allows realizing materials with largely different properties. The silanolate end groups remain active, which is the key to self‐healing. Elastomeric behavior is observed at room temperature, while viscous flow dominates at higher temperatures (typically 80 °C). The elasticity is essential for reversible actuation and the thermoreversible softening allows for self‐healing and recycling. The dielectric permittivity can be increased to a maximum value of 18.1 by varying the polar group content. Single‐layer actuators show 3.8% lateral actuation at 5.2 V µm –1 and self‐repair after a breakdown, while damaged ones can be recycled integrally. Stack actuators reach an actuation strain of 5.4 ± 0.2% at electric fields as low as 3.2 V µm –1 and are therefore promising for applications as artificial muscles in soft robotics.

These devices find applications in important emerging fields such as personalized medicine, renewable energy, and soft robotics. However, even after years of research, it is still a great challenge to achieve DEs with increased dielectric permittivity and fast recovery of initial shape when subjected to mechanical and electrical stress. Additionally, high dielectric permittivity elastomers that show reliable performance but disintegrate under normal environmental conditions are not known. Here, we show that polysiloxanes modified with amide groups give elastomers with a dielectric permittivity of 21, which is 7 times higher than regular silicone rubber, a strain at break that can reach 150%, and a mechanical loss factor tan δ below 0.05 at low frequencies. Actuators constructed from these elastomers respond to a low electric field of 6.2 V μm −1 , giving reliable lateral actuation of 4% for more than 30 000 cycles at 5 Hz. One survived 450 000 cycles at 10 Hz and 3.6 V μm −1 . The best actuator shows 10% lateral strain at 7.5 V μm −1 . Capacitive sensors offer a more than a 6-fold increase in sensitivity compared to standard silicone elastomers. The disintegrated material can be re-cross-linked when heated to elevated temperatures. In the future, our material could be used as dielectric in transient actuators, sensors, security devices, and disposable electronic patches for health monitoring.

to a voltage below 500 V, for which generation of cheap and small-scale electronics are sufficient. [6] Two different materials are necessary for DEAs: dielectric elastomers and electrode materials. The former should be soft with high dielectric permittivity and high breakdown strength, while the latter should be sufficiently conductive to allow fast charging of the capacitor without energy losses due to resistive heating. Ideally, the materials should be processable into films with a thickness below 100 µm without using solvents. Furthermore, the films should cross-link fast in ambient atmosphere and the crosslinked layers should not delaminate after repetitive stretching.The setup of a DEA is schematically shown in Figure 1. When a voltage is applied between the electrodes, the dielectric elastomer film is compressed by the electrostatic pressure of the oppositely charged electrodes and elongates in the x,y-plane. The electrostatic pressure, p, equals the product of the permittivity of free space, ε 0 , the relative permittivity of the elastomer, ε r , and the square of the electric field, E 2 , (Equation (1)).