The laccase‐catalyzed oxidative polymerization of monomeric and dimeric lignin model compounds was carried out with oxygen as the oxidant in aqueous medium. The oligomers were characterized by using gel permeation chromatography (GPC) and matrix‐assisted laser desorption ionization time‐of‐flight mass spectroscopy (MALDI‐TOF MS) analysis. Oxidative polymerization led to the formation of oligomeric species with a number‐average molecular weight (M_n) that ranged from 700 to 2300 Da with a low polydispersity index. Spectroscopic analysis provided insight into the possible modes of linkages present in the oligomers, and the oligomerization is likely to proceed through the formation of C−C linkages between phenolic aromatic rings. The oligomers were found to show good UV light absorption characteristics with high molar extinction coefficient (5000–38 000 m⁻¹ cm⁻¹) in the UV spectral region. The oligomers were blended independently with polyvinyl chloride (PVC) by using solution blending to evaluate the compatibility and UV protection ability of the oligomers. The UV/Vis transmittance spectra of the oligomer‐embedded PVC films indicated that these lignin‐like oligomers possessed a notable ability to block UV light. In particular, oligomers obtained from vanillyl alcohol and the dimeric lignin model were found to show good photostability in accelerated UV weathering experiments. The UV‐blocking characteristics and photostability were finally compared with the commercial low‐molecular‐weight UV stabilizer 2,4‐dihydroxybenzophenone.

中文翻译：

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漆酶催化的低分子量木质素样低聚物的合成及其在紫外线阻隔材料中的应用

单体和二聚体木质素模型化合物的漆酶催化氧化聚合反应是在水介质中以氧气为氧化剂进行的。通过使用凝胶渗透色谱（GPC）和基质辅助激光解吸电离飞行时间质谱（MALDI-TOF MS）分析来表征低聚物。氧化聚合导致形成数均分子量（M _n）范围从700到2300 Da，且低多分散指数。光谱分析提供了对低聚物中可能存在的连接方式的见解，并且低聚反应很可能通过酚芳族环之间的C-C键的形成而进行。发现该低聚物具有良好的紫外线吸收特性，且消光系数高（5000–38 000  m ^-1  cm ^-1）在紫外线光谱范围内。通过使用溶液共混来评估低聚物的相容性和紫外线防护能力，将低聚物与聚氯乙烯（PVC）独立共混。包埋有低聚物的PVC薄膜的UV / Vis透射光谱表明，这些类木质素的低聚物具有显着的阻挡UV光的能力。特别地，发现从香草醇和二聚体木质素模型获得的低聚物在加速的紫外线风化实验中显示出良好的光稳定性。最后，将紫外线阻隔特性和光稳定性与市售的低分子量紫外线稳定剂2,4-二羟基二苯甲酮进行了比较。