High-strength self-healing moisture-curable polyurethane enabled by synergistic dynamic disulfide bonds and multiple hydrogen bonds

Moisture-curable polyurethane (MCPU) is widely utilized but is often limited by poor mechanical properties caused by environmental damage. In this work, a high-strength MCPU with exceptional self-healing properties was fabricated by incorporating two chain extenders containing aromatic disulfide bonds and hydrazide groups. The formation of multiple hydrogen bonds among acylsemicarbazide(ASCZ) groups, generated through the reaction between hydrazide and isocyanate, significantly enhances the microphase separation structure and mechanical properties. The optimized MCPU achieves a tensile strength of 20.43 MPa and an elongation of 2071.57 %, representing 4.93-fold and 5.92-fold improvements over the relevant ASTM D6947/D6947-16 standards (4.14 MPa and 350 %), respectively. Furthermore, the optimized MCPU exhibits a remarkable self-healing properties attributed to the dynamic exchange of disulfide bonds, which facilitates molecular chain rearrangement. This work presents an innovative strategy for designing MCPU materials with superior mechanical and self-healing properties, paving the way for advanced applications in durable and sustainable materials.