Multifunctional imidazole-functionalized polyaspartamide/TiO2 composites for UV screening, heavy metal removal, and suppressed photocatalytic activity

With the acceleration of global warming, increased exposure to ultraviolet (UV) radiation resulting from ozone layer depletion has raised significant concerns about skin-related health risks. Inorganic sunscreens, particularly those based on titanium dioxide (TiO 2 ), are commonly used but face limitations such as visible white turbidity and skin oxidation caused by the photocatalytic activity of TiO 2 . In this study, we synthesized TiO 2 /polyaspartamide composites (T-PH and T-PA) functionalized with histamine and aminopropyl imidazole, respectively. These imidazole-bearing polymers were covalently grafted onto TiO 2 nanoparticles, enhancing their dispersion stability and enabling efficient heavy metal adsorption through metal–ligand coordination. Compared to unmodified TiO 2 , the composites exhibited a substantial reduction in white turbidity (up to a 33 % decrease in whiteness index) and significantly suppressed photocatalytic degradation of methylene blue (from 100 % to 16–30 %). Furthermore, the composites demonstrated improved adsorption capacities for Cu 2+ and Ni 2+ ions. These multifunctional TiO 2 –polymer hybrids hold strong potential for next-generation sunscreens by offering effective UV shielding, enhanced optical transparency, and environmental remediation capabilities. This study presents the synthesis of TiO 2 /polyaspartamide composites (T-PH and T-PA) for advanced sunscreens, enhancing TiO 2 dispersion, reducing photocatalytic activity, and improving UV protection while minimizing skin whitening and oxidation. The materials also demonstrated improved heavy metal adsorption capabilities.