Plant-based self-healing waterborne polyurethane films for effective UV shielding

The functional integration of multiple molecules into polymeric materials by covalent cross-linking is a promising strategy. Here, we report a double crosslinked aqueous polyureaurethane prepared by the introduction of curcumin and dithiodiphenylamine into the castor oil-isophorone diisocyanate system. The results show that the bicovalent crosslinking system promotes microphase separation, leading to tunable mechanical properties from flexible to rigid. Since the π→π∗ transition of curcumin is preserved, The CSWPU film achieves 100 % shielding efficiency against short-wavelength light (<500 nm) while maintaining optical transparency, and exhibits rapid self-healing via a dynamic disulfide exchange mechanism with a healing efficiency of 91 %.The denser cross-linking network also improved thermal stability. This work establishes a sustainable paradigm for the design of multifunctional polymers through rational molecular cross-linking.