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 (Tfs) 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 Tf 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.