Towards mechanical robust yet self-healing polyurethane elastomers via combination of dynamic main chain and dangling quadruple

One of the greatest challenges of robust self-healing materials is the confliction between high chain mobility for self-healing and a stable structure for mechanical strength. Herein, dangling 2-ureido-4[1R]-pyrimidione (UPy)-functionalized side groups were introduced into the hard segments of thermoplastic polyurethane (TPU) elastomers, where embedded the dynamic disulfide bonds in the main chain. The strong quadruple H-bonding interaction between UPy side groups acts as supramolecular crosslinkers enabling the TPU elastomer to have improved mechanical properties (tensile strength up to 25 MPa and toughness similar to 100 MJ m(-3)), and simultaneously the plasticizer effect of dangling side chain endows it with efficient healing ability at elevated temperatures (80-100 degrees C) comparable to its linear analogues. This strategy shows great potential in designing robust self-healing TPU elastomer employing weak dynamic covalent bonds, with wide promising applications as wearable electronics, coatings and adhesives.