Preparation of High‐Performance Waterborne Polyurethane With Hybrid Flexible Soft Segment and Its Modified Emulsified Asphalt

The application of waterborne polyurethane (WPU) in emulsified asphalt (EA) is often restricted by limited compatibility and insufficient comprehensive performance. Herein, a high‐performance WPU (HWPU) was synthesized via a hybrid soft‐segment strategy using hydroxyl‐terminated polybutadiene (HTPB) and polytetramethylene ether glycol (PTMG). The nonpolar PB segments promoted microphase separation and enhanced interfacial compatibility with asphalt. The resulting HWPU film achieved a tensile strength of 24.4 MPa and 1456% elongation. Consequently, HWPU‐modified EA (HWPU‐MEA) demonstrated superior high‐temperature performance, evidenced by a rutting factor (G*/sin δ ) of 26.1 kPa at 110°C. MSCR tests at 90°C revealed outstanding elastic recovery ( R 0.1 = 99.68%; R 3.2 = 72.41%) and minimal permanent deformation ( J nr 0.1 = 0.43 × 10 −3 kPa −1 ; J nr 3.2 = 0.36 × 10 −1 kPa −1 ). Additionally, HWPU‐MEA displayed remarkable low‐temperature crack resistance and extended fatigue life. Mechanism analysis attributes these performance enhancements to the formation of a continuous HWPU network structure within the asphalt matrix at an optimal dosage of 15%–20%. This work provides an effective modification strategy for producing high‐performance paving materials suitable for heavy‐duty road engineering.