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 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.