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

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[1H]-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 ~100 MJ m−3), and simultaneously the plasticizer effect of dangling side chain endows it with efficient healing ability at elevated temperatures (80–100 °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.