From molecular architecture to rheological differentiation: Multiscale regulation of asphalt by waste colza oil-derived polymers

Developing structurally tunable polymeric modifiers from waste vegetable oil offers a sustainable alternative to petroleum-derived asphalt modifiers while providing a high-value utilization pathway for waste resources. However, how the molecular architecture of waste-oil-derived polymers regulates asphalt performance across multiple scales remains poorly understood. To address this gap, industrial waste colza oil was converted into structurally tunable waste colza oil-based polymers (WCOPs) through epoxidation, acrylation, and free-radical polymerization, providing a high-value utilization route for waste vegetable oil. The effects of WCOP molecular architecture on the rheological behavior, nanomorphology, and molecular interactions of asphalt were systematically investigated using dynamic shear rheometer test, atomic force microscopy, Fourier transform infrared spectroscopy, and molecular dynamics simulations. The results showed that WCOP modification did not produce uniform performance enhancement, but instead generated differentiated rutting and fatigue responses depending on molecular architecture and dosage. WCOP-H exhibited the most pronounced improvement, with 10 wt% WCOP-H reducing Jnr.3.2 b y up to 26.61%, increasing R by up to 87.52%, and improving fatigue life by up to 81.74%. Multiscale mechanistic analyses across molecular, interfacial, and nanoscale levels showed that WCOP modification was dominated by physical blending without the formation of new chemical bonds. WCOP molecular architecture regulated asphalt through the balance between molecular mobility and intermolecular interactions. Higher molecular mobility promoted diffusion, interfacial penetration, and structural relaxation, whereas stronger intermolecular interactions enhanced localized structural organization and elastic support. These findings establish the relationships among molecular architecture, microstructure, and performance, and provide a mechanistic basis for the targeted design of waste-oil-derived polymer modifiers.