Suppressing photo-oxidative degradation: Biomimetic allomelanin enhances the UV-aging resistance of polyvinyl alcohol films

DHN-derived allomelanin nanoparticles were incorporated into PVA at 0.1–0.7 wt%. • At 0.3 wt%, tensile strength and elongation reached 103.8 MPa and 102.1%. • Loadings of 0.5–0.7 wt% enhanced light shielding and photothermal heating. • FTIR and AFM indicated reduced UV-induced chemical and surface changes. 1,8-Dihydroxynaphthalene-derived allomelanin nanoparticles (AMNPs) were incorporated into poly(vinyl alcohol) (PVA) films at low loadings of 0.1–0.7 wt% to regulate their mechanical, optical, photothermal, and UV-aging properties. The 0.3 wt% film exhibited the best measured strength–ductility balance, with a tensile strength of 103.8 MPa and an elongation at break of 102.1%, while retaining partial visible transparency. Increasing the AMNPs loading enhanced UV attenuation and photothermal heating but reduced visible-light transmittance. The 0.5 and 0.7 wt% films reached steady-state temperatures of 60.7 and 62.4 °C, respectively. In the curcumin photodegradation test, the 0.3 wt% film limited degradation to 6% after 50 min of UV exposure, whereas the 0.5 and 0.7 wt% films nearly completely suppressed degradation. After 120 h of laboratory UV irradiation, the AMNP-containing film showed less surface roughening than neat PVA. These results reveal composition-dependent performance windows: 0.3 wt% favors mechanically robust and partially transparent UV-protective films, whereas 0.5–0.7 wt% favors stronger light shielding and photothermal conversion. Download: Download high-res image (325KB) Download: Download full-size image