Dynamic chemical bonds design strategy for fabricating fast room-temperature healable dielectric elastomer with significantly improved actuation performance

Abstract

Dielectric elastomers are indispensable for soft actuators due to their fast actuation response and diverse configuration. However, the existing dielectric elastomers have poor electromechanical performance and are vulnerable to damage or failure, highlighting an urgent need for materials with remarkable dielectric, mechanical and self-healing properties. Aiming at these requirements, we herein propose an extraordinary design strategy of supramolecular elastomer by combining multitype dynamic chemical bonds via synthesizing, which is different from most previously reported dielectric elastomers. This strategy includes three typical features: (i) The S-S metathesis coupled with multi-degree hydrogen bonds provides the supramolecular poly(urethane-urea) (PUU) elastomer with fast room-temperature healability and ultrahigh efficiency. After mechanical damage, the electrical property completely recovered after ∼ 20 min restoration, and the mechanical performance is restored by 96% after healing at room temperature for 3 h, much higher than that of the elastomer without disulfide bonds (13%). (ii) Highly polar urethane and urea groups endow the supramolecular PUU elastomer with excellent dielectric properties (εr = 10.9@1 kHz). (iii) The aliphatic disulfide bonds have the capability to reduce the Young's modulus from 2.98 to 1.76 MPa by virtue of its dynamic exchange characteristic. These merits allow the resulting actuator to be more sensitive to driving field. Compared with the control sample, the area strain (at 60 MV/m) and bending angle (at 30 MV/m) for supramolecular elastomer is ∼ 4 and ∼ 2.2 times higher, respectively. As an example, a switch controlling a series circuit illustrates the potential application of such electric-field-activated actuators in high-voltage devices.