Robust, Stretchable, and Self-Healable Supramolecular Elastomers Synergistically Cross-Linked by Hydrogen Bonds and Coordination Bonds.

Abstract

Polymeric elastomers integrated with high mechanical toughness and excellent self-healing ability can find attractive applications in electronic skin, soft robotics, and electrical devices. However, simultaneously enhancing the mechanical and self-healing properties of elastomers is still a great challenge because it is difficult to balance the effects between strong and weak cross-linking bonds. Here, a novel self-healing elastomer is developed via a one-pot polycondensation reaction between bis(3-aminopropyl)-terminated poly(dimethylsiloxane) and 2,4'-tolylene diisocyanate, followed by being coordinated with Al(III) ions by metal-coordination bonds. In this elastomer system, the quadruple hydrogen bonds not only are able to achieve rapid reformation after fracture but also can dissipate strain energy as a weak dynamic bond, endowing the elastomer with excellent self-healing ability and high stretchability, while the treble Al-coordination bonds acting as a strong dynamic bond contribute to the robust molecular networks, leading to the significantly improved robustness and elasticity of the self-healing elastomer. Owing to the accuracy design, the synthesized elastomer exhibits all the desired properties, including high tensile stress (2.6 MPa), exceptional toughness (∼14.7 MJ m-3), high stretchability (∼1700%), and excellent self-healing ability (90%). The robust self-healing elastomer enables the easy fabrication of flexible electronic skin, which will open a new avenue for next-generation electrical devices.