High‐Performance Polymeric Materials through Hydrogen‐Bond Cross‐Linking

It has always been critical to develop high‐performance polymeric materials with exceptional mechanical strength and toughness, thermal stability, and even healable properties for meeting performance requirements in industry. Conventional chemical cross‐linking leads to enhanced mechanical strength and thermostability at the expense of extensibility due to mutually exclusive mechanisms. Such major challenges have recently been addressed by using noncovalent cross‐linking of reversible multiple hydrogen‐bonds (H‐bonds) that widely exist in biological materials, such as silk and muscle. Recent decades have witnessed the development of many tailor‐made high‐performance H‐bond cross‐linked polymeric materials. Here, recent advances in H‐bond cross‐linking strategies are reviewed for creating high‐performance polymeric materials. H‐bond cross‐linking of polymers can be realized via i) self‐association of interchain multiple H‐bonding interactions or specific H‐bond cross‐linking motifs, such as 2‐ureido‐4‐pyrimidone units with self‐complementary quadruple H‐bonds and ii) addition of external cross‐linkers, including small molecules, nanoparticles, and polymer aggregates. The resultant cross‐linked polymers normally exhibit tunable high strength, large extensibility, improved thermostability, and healable capability. Such performance portfolios enable these advanced polymers to find many significant cutting‐edge applications. Major challenges facing existing H‐bond cross‐linking strategies are discussed, and some promising approaches for designing H‐bond cross‐linked polymeric materials in the future are also proposed.