A Novel Lignin/ZnO Hybrid Nanocomposite with Excellent UV-Absorption Ability and Its Application in Transparent Polyurethane Coating

In this work, lignin/zinc oxide nanocomposites with excellent UV-absorbent performance were prepared through a novel hydrothermal method using industrial alkali lignin (AL) as raw materials. AL was first modified by quaternization to synthesize quaternized alkali lignin (QAL). The QAL/ZnO nanocomposites with different lignin contents were then prepared via a facile one-step hydrothermal method using QAL and zinc nitrate hexahydrate and hexamethylenetetramine in aqueous solution. The prepared nanocomposite possessed an average diameter of ∼100 nm and showed excellent synergistic UV-absorbent performance. The particle morphology and hybrid structure were carefully characterized by SEM, TEM, XRD, FT-IR, XPS, UV–vis, and TG analyses. Interestingly, it was found that the UV transmittance of polyurethane (PU) film was significantly reduced and the mechanical properties of the PU were significantly enhanced when blended with the prepared QAL/ZnO nanocomposite. The results of this work were of practical importance for high value-added application of industrial lignin in the field of functional materials

In Situ Synthesis of Flowerlike Lignin/ZnO Composite with Excellent UV-Absorption Properties and Its Application in Polyurethane

In this work, lignin-decorated ZnO composite was prepared via an in situ synthesis method using industrial alkali lignin (AL). First, the AL was modified by quaternization to prepare quaternized alkali lignin (QAL). The microstructure and optical properties of the QAL/ZnO composite were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and UV–vis and photoluminescence (PL) spectroscopy. These results showed that the prepared QAL/ZnO composite possessed a flowerlike structure and showed excellent synergistic UV-absorbent properties. Interestingly, the anti-UV performance and mechanical properties of polyurethane (PU) were significantly improved when it was blended with the resulting QAL/ZnO. In comparison with pure PU film, the UV transmittance of the PU film was rapidly reduced. Furthermore, the tensile strength and elongation at break of PU film blended with QAL/ZnO were significantly improved, which was due to good compatibility between QAL/ZnO and PU matrix. Results of this work provide a significant and practical approach for the high value-added utilization of lignin as a functional material