Highly Tough Room-Temperature Self-Healing Polyurethane with Thermochromic Properties Based on Dynamic Covalent Bonding and Multiple H-Bonding

Polymer materials with high mechanical strength, sensing, and self-healing capabilities have significant application potential. However, achieving an optimal balance of these properties within a single material is a formidable challenge. In this study, a polyurethane elastomer, TUPU-75, with excellent performance was prepared using a dual-hard-segment strategy through polycondensation of dihydroxy-functionalized tetraaryl succinonitrile (TASN-diol), ureidopyrimidinone (UPy), polytetrahydrofuran (PTMEG 1000), and dicyclohexylmethane diisocyanate (HMDI). By controlling the ratio of dynamic covalent bonds to quadruple hydrogen bonds, the mechanical properties of the material can be adjusted. When the ratio of the two groups is 1:3, the prepared elastomer exhibits excellent mechanical properties (a mechanical strength of 18.05 MPa and a tensile strain of 1241%) and room-temperature self-healing ability (a healing efficiency of 96.7% for completely fractured TUPU-75 after 24 h of healing at room temperature). Furthermore, the presence of dynamic covalent chromophores confers excellent thermochromic properties to TUPU-75. We hope that this exceptionally durable, color-changing, and self-healing material could offer novel perspectives on the development of multifunctional polyurethane materials.