Shifting the mechanical strength-healing efficiency trade-off of polyurethanes by incorporating boronic ester bonds and hydrogen bonding

Abstract

It is challenging to design and synthesize elastomers with both good mechanical performance and high healing efficiency because their mechanisms are mutually exclusive. This work aims to shift the trade-off between them by incorporating dynamic non-covalent bonds via 2-ureido-4[1H]-pyrimidione (UPy) and dynamic covalent bonds via boronic ester bonds into polyurethane. The quadruple hydrogen bonds between UPy dimers serve as physical crosslinks, improving the overall mechanical properties of the polyurethane, while the boronic esters facilitate its healing. The resulting polyurethane can achieve an ultimate stress of 27.4 MPa and a healing efficiency of 90 %. The effect of healing time on the healing efficiency is modeled and discussed.