Engineering highly transparent UV-shielding films with disassembled polydopamine oligomers as light adsorber

In this study, a highly transparent ultraviolet (UV)-shielding film was prepared by developing disassembled polydopamine (dPDA) oligomers as active UV light absorbers, followed by the incorporation into the matrix of polyvinyl alcohol (PVA) via a solvent casting method. It was shown the composite film with only 0.5 wt% of dPDA addition could barrier 99.3% of UV light (wavelength of 200?400 nm), without compromising the film transparency. Such excellent UV-shielding ability was attributed to the limited inter- and intra-molecular conjugations in dPDA oligomers which can be well dispersed in PVA matrix. Besides, the weakened molecular conjugations in dPDA led to obvious blue-shift of UV?vis absorbance, and thus strong absorbance in UV region but high transmittance in visible region. Moreover, the dPDA/PVA films exhibit higher photostability than PDA/ PVA ones due to the absence of free radicals in dPDA, which was advantageous to avoid the photoaging in the long-term use under UV irradiation. This work proves the feasibility of dPDA oligomers as highly efficient light absorbers used for UV-shielding films and provides some new insights to overcome the trade-off effect between transparency and UV-shielding for preparing high-performance UV-shielding films.