Design of Dynamic Polyurethanes toward Ultrahigh-Performance Asphalt

Polyurethanes (PUs) are promising materials for enhancing the mechanical strength and stretchability of asphalt under both high- and low-temperature conditions. However, the poor compatibility with asphalt and high viscous flow temperatures (T_fs) of conventional PUs impede their application in asphalt. Herein, disulfide is used as the chain extender to design a dynamic PU, achieving a PU-asphalt with ultrahigh performance. The flexibility of the disulfide bond improves the compatibility of PU with asphalt, and the tensile strength and elongation at the break of this PU-asphalt are 8.3 MPa and 948.6%, respectively, surpassing most reported PU-modified asphalts. Meanwhile, this PU-asphalt has a moderate T_f of 128.8 °C due to the dynamicity of the disulfide bond. This not only provides remarkable high-temperature performance but also enables processing at moderate temperatures. Additionally, this PU-asphalt exhibits outstanding low-temperature performance, owing to the flexibility of the PU molecules.