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

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 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.