A self-healing dielectric supramolecular elastomer modified by TiO₂/urea particles

We designed and prepared a new dielectric self-healing elastomer (TuSE) by introducing the core-shell structured TiO₂/urea particles into self-healing supramolecular elastomer (SE) assembled by hydrogen bonds. The urea on the outer shell of TiO₂ particles forms hydrogen bonds with the amide groups in the molecular chains, so the TuSE materials exhibit higher self-healing efficiency than SE. The TuSE with 1% TiO₂/urea particles (TuSE-1%) recovers its mechanical properties within 24 h at room temperature without any external stimulus. Moreover, the TiO₂/urea particles effectively improve the dielectric constant (ε′) and actuated properties of the supramolecular elastomer. The TuSE-1% exhibits a much higher dielectric constant (ε′ = 16.1 at 1 kHz) and much lower elastic modulus (Y = 0.14 MPa) than those of SE (ε′ = 10.8 and Y = 3.78), resulting in a large increase in electromechanical sensitivity from 2.9 MPa⁻¹ for pure SE to 115 MPa⁻¹ for TuSE-1%. The dielectric elastomer actuator made of TuSE-1% shows a lateral actuation strain of 7.53% at 8.5 V μm⁻¹, 20 times higher than that of pure SE (0.37% at 9 V μm⁻¹). Additionally, TuSE-1% fully recovers its dielectric properties within 24 h, and the actuator can operate again after first breakdown.