Ultra-stretchable and ultra-low temperature self-healing polyurethane enabled by dual dynamic bonds strategy

The successful development of polyurethane with excellent low-temperature self-healing capability will facilitate it to find wider applications in composite solid propellants and other fields. Here, we report a design strategy that both quadruple hydrogen bonds and aliphatic disulfide bonds are introduced into polyurethane networks to achieve an ultra-stretchable and ultra-low temperature self-healing polyurethane. The polyurethane has excellent mechanical properties, including high tensile strength and elongation at breaks of 1303.56%, 1503.42%, 2381.88%, and 1814.07% at −40 °C, −20 °C, 25 °C, and 60 °C, respectively. Furthermore, after self-repair at −20 °C, the elongation at break of the cut polyurethane can reach 1120.14%, and the repair efficiency is 74.5%, whereas at −40 °C, the elongation at break and repair efficiency are 811.75% and 62.2%, respectively, which are rarely seen in the literature. In addition, the glass transition temperature of the polyurethane is extremely low (−78.34 °C), which facilitates their low-temperature application. The excellent properties of the prepared polyurethane will allow the preparation of composite solid propellants for use in a wider temperature range. More importantly, the proposed material is expected to have broader application prospects such as in cold-proof coatings, electronic devices, and so on. • The dynamic disulfide bonds and quadruple hydrogen bonds were combined into the PU network. • An ultra-stretchable and ultra-low temperature self-healing polyurethane was synthesized. • Quadruple hydrogen bonds can increase the initial modulus of PU. • The interaction of quadruple hydrogen and disulfide bonds enables them to be quickly exchanged and rearranged. • The rapid exchange reaction of dual dynamic bonds can dissipate a large amount of strain energy in the PU network.