Engineering of Chain Rigidity and Hydrogen Bond Cross-Linking toward Ultra-Strong, Healable, Recyclable and Water-Resistant Elastomers.

High-performance elastomers have gained significant interest because of their wide applications in industry and our daily life. However, it remains a great challenge to fabricate elastomers simultaneously integrating ultra-high mechanical strength, toughness, and excellent healing and recycling capacities. In this study, ultra-strong, healable, and recyclable elastomers are fabricated by dynamically cross-linking copolymers composed of rigid polyimide (PI) segments and soft poly (urea-urethane) (PUU) segments with hydrogen bonds. The elastomers, which are denoted as PI-PUU, have a record-high tensile strength of ∼142 MPa and an extremely high toughness of ∼527 MJ m -3 . The structure of the PI-PUU elastomer contains hydrogen-bond-cross-linked elastic matrix and homogenously dispersed rigid nanostructures. The rigid PI segments self-assemble to generate phase-separated nanostructures that serve as nanofillers to significantly strengthen the elastomers. Meanwhile, the elastic matrix is composed of soft poly (urea-urethane) (PUU) segments cross-linked with reversible hydrogen bonds, which largely enhance the strength and toughness of the elastomer. The dynamically cross-linked PI-PUU elastomers can be healed and recycled to restore their original mechanical strength. Moreover, because of the excellent mechanical performance and the hydrophobic PI segments, the PI-PUU elastomers are scratch-, puncture- and water-resistant. This article is protected by copyright. All rights reserved.