木质素抗紫外辐射性能应用研究进展

天然木质素一般是由愈创木基、紫丁香基和对羟苯基3种基本结构单元通过不同的碳氧键、碳碳键等连接形成的复杂大分子聚合物。作为自然界中含量丰富的天然芳香类聚合物,木质素及其衍生物具有广阔的应用潜力。木质素中含有芳基、酚羟基、酮基以及羧基等官能团,赋予了木质素一定的抗氧化性与抗紫外辐射性能。研究证明,木质素无论在植物的生长发育还是后续利用中都展示出良好的抗紫外辐射能力。木质素作为一种天然的紫外线防护剂,其抗紫外辐射功能的开发与利用逐渐引起了研究者们的关注。笔者重点介绍了木质素抗紫外辐射性能在防晒产品中的研究进展及其应用现状,探讨了木质素的抗氧化性能对其抗紫外辐射性能的影响,并对当前研究中存在的问题进行了分析。最后,结合木质素结构特点,对其抗紫外辐射性能在防晒应用中的发展方向和前景进行了展望,为木质素高值化利用提供一定的参考。

Recent advances of anti-UV radiation of lignin

Lignin is primarily formed by combinatorial radical coupling of three typical p-hydroxycinnamyl alcohols(known as monolignols),p-coumaryl alcohol,coniferyl alcohol,and sinapyl alcohol that differ in the degree of methoxylation of the aromatic ring,and result in p-hydroxyphenyl,guaiacyl,and syringyl units in lignin polymers.Lignin is a major component in plant cell walls and the largest potential source of aromatic compounds,which plays an essential role in plant development and strongly affect the application of sustainable lignocellulosic biomass.As one of the highly abundant natural and renewable polymers,lignin is rich in aromatic rings in nature due to its basic phenylpropane unit.Despite the aromatic nature,lignin also contains various functional groups including phenolic hydroxyl groups,carboxyl groups,aliphatic hydroxyl groups,and double bonds,etc.,which has drawn much research interest and industrial attention for decades.However,it has been the most challenging task for researchers to understand the composition and structure of lignin because of its complexity and heterogeneity,to some extent,which also hinders the pace toward high-value utilization of lignin.As a result of the diversity of lignin functional groups,lignin applications cover a wide range,including the production of power,biofuels,and syngas products,the formation of macromolecules such as plastics,polymeric foams,adhesives,additives in biodegradable composite materials,membranes,and carbon fibers,antioxidants,as well as anti-microbial agents.Lignin has been proven to be a good UV-absorber and a nature broad-spectrum sun blocker due to the containing of UV absorbing functional groups such as phenolic,ketone and other chromophores in lignin polymers.Using lignin as sunscreen additives can greatly promote the technical high-end applications of lignin.Therefore,applications for UV absorption of lignin or lignin derivatives,such as lignin-based sunscreens,have drawn more and more attention recently.In this review,the recent advances of anti-UV radiation of lignin using in sunscreens were highlighted and summarized,and the influence on sun protection factor(SPF) value of lignin-based sunscreens by their antioxidant properties was discussed.Moreover,the current issues and prospects for the development of this field were addressed and discussed,which will provide useful information for high-value utilization of lignin.