Sustainable development of novel UV-shielding microcapsules with CeO₂/polymer composite shell containing waste soybean cooking oil for autonomous self-healing and anti-aging in bitumen

CeO₂ nanoparticles markedly enhance the thermal stability of polymer microcapsule shells. • The composite shell blocks ultraviolet radiation and scavenges reactive oxygen species. • Waste soybean oil released from ruptured microcapsules restores bitumen crack integrity. • Multi-cycle self-healing is achieved through sustained oil release and matrix preservation. • A coupled protection-healing mechanism yields synergistic damage reduction in bitumen. The self-propagating cycle of ultraviolet aging and mechanical cracking limits the service life of bituminous infrastructure. This work interrupts this cycle using microcapsules with a cerium oxide (CeO₂) polymer composite shell encapsulating waste soybean cooking oil. The CeO₂ nanoparticles elevate shell decomposition temperature from 184 °C to above 250 °C and reduce UV transmittance to less than 10% in the UV B and UV C regions. After 14 days of accelerated UV aging, the carbonyl index accumulation is reduced by 47%. Upon crack propagation, the shell ruptures and releases the oil, achieving 99% self-healing efficiency at 20 °C for the first fracture cycle and maintaining 79% efficiency after five consecutive cycles. A coupled damage evolution model reveals a synergy factor of 3.4 for the 5 wt% CeO₂ formulation, demonstrating that the integrated protection and repair mechanisms reduce accumulated damage more than three times as effectively as the sum of independent contributions. This closed loop architecture demonstrates a potential pathway to transform waste oil into a functional resource while embedding proactive UV defense and autonomous crack healing. Download: Download high-res image (284KB) Download: Download full-size image