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林业科学 ›› 2016, Vol. 52 ›› Issue (3): 90-96.doi: 10.11707/j.1001-7488.20160311

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点击化学在木质纤维素化学修饰中的研究现状

熊福全1, 韩雁明1, 李改云1, 秦特夫1, 王思群1,2, 储富祥1   

  1. 1. 中国林业科学研究院木材工业研究所 北京 100091;
    2. 美国田纳西大学再生碳中心 Tennessee 37996-4570
  • 收稿日期:2015-04-20 修回日期:2015-05-31 出版日期:2016-03-25 发布日期:2016-04-08
  • 通讯作者: 储富祥
  • 基金资助:
    中央级公益性科研院所基本科研业务费专项资金(CAFINT2014K01)。

Research Status of Click Chemistry Used for Chemical Modification of Lignocellulose

Xiong Fuquan1, Han Yanming1, Li Gaiyun1, Qin Tefu1, Wang Siqun1,2, Chu Fuxiang1   

  1. 1. Research Institute of Wood Industry, CAF Beijing 100091;
    2. Center for Renewable Carbon, University of Tennessee USA Tennessee 37996-4570
  • Received:2015-04-20 Revised:2015-05-31 Online:2016-03-25 Published:2016-04-08

摘要: 化学修饰可改善木质纤维素和聚合物基质的相容性且使其具有特定功能。点击化学作为化学修饰的一种重要方法,是由2001年诺贝尔化学奖获得者Sharpless首次提出的,主要包括铜催化叠氮-炔基环加成反应(CuAAC)、环张力催化叠氮-炔基环加成反应(SPAAC)、巯基-烯/炔点击反应(Thiol-Ene/Yne)和狄尔斯-阿尔德尔环加成反应(Diels-Alder)等反应类型。相比传统接枝修饰方法,点击化学具有反应条件温和、环境污染小、副反应少、分离提纯简单、产量和效率高等优点,在木质纤维素的化学修饰方面已有相关应用。在点击反应方法方面,CuAAC反应是一种最普遍的点击反应类型,也是对木质纤维素化学修饰应用最多的一类反应;但CuAAC反应后催化剂很难移除,在一定程度上限定了反应后产品的用途,将Cu(Ⅰ)通过共价键结合在纳米纤维素气凝胶的表面能使点击反应中的铜有效回收。相比CuAAC反应,Thiol-Ene/Yne反应不需要有毒的铜作为催化剂。点击化学在纤维素的研究方面,将纤维素自身或与聚合物进行点击反应能制备水凝胶和片状纳米纤维素凝胶;此外,荧光标记的纤维素材料能证明点击反应的发生,通过2种点击反应能制备多色荧光标记的纳米纤维素材料。点击化学在半纤维素和木质素的研究方面,木聚糖通过与聚乳酸进行点击反应形成共聚物,能降低玻璃化转变温度,提高热分解温度。通过CuAAC反应能形成苯三唑连接高产率的邻位木糖苷和木二糖苷。木质素和聚苯乙烯通过点击反应能制备一种热塑性聚合物。此外,通过生物正交点击化学能描述活体植物细胞壁的木质化过程。点击化学在木质纤维素上的应用还没有深入研究,扩大点击化学在木质纤维素上的应用范围仍然需要进一步探索。由于点击反应的条件比较温和,很多反应都能在室温下进行,非常有利于在生物医用材料领域的研究,并且纤维素和半纤维素等多糖又具有良好的生物相容性,为纤维素和半纤维素在生物领域的应用创造了有利条件。此外,由于铜催化的毒性作用,无铜催化的点击反应可能会作为一个重要发展方向,像环张力催化叠氮-炔基环加成反应、Diels-Alder反应和Thiol-Ene/Yne反应。

关键词: 点击化学, 纤维素, 半纤维素, 木质素

Abstract: Chemical modification can improve the compatibility of lignocellulose with polymeric matrices, and make lignocellulose owned specific function. Click chemistry, a kind of important method used for chemical modification, was firstly proposed by Sharpless and co-workers in 2001. Its typical reaction types include copper-catalyzed azide-alkyne cycloaddition (CuAAC), strain-promoted alkyne-azide cycloaddition reaction (SPAAC), thiol-ene/yne click reaction and diels-alder click reaction, etc. Compared with the traditional grafting modification method, click chemistry was found to be mild reaction conditions, environmental friendly, easy to implement and very efficient. It has been applied in the chemical modification of lignocelluloses. In terms of click reaction method, the CuAAC reaction is the most common click reaction used for the chemical modification of lignocellulose. However, the catalyst is difficult to remove after the CuAAC reaction so that the application of the products is limited to some extent. The Cu (Ⅰ), which is linked with aerogels of cellulose nanofibrils through covalent bonding, can be recycled efficiently after click reaction. Compared with the CuAAC reaction, the Thiol-Ene/Yne reaction does not need the toxic copper as a catalyst. In terms of cellulose research, hydrogel and nanoplatelet could be prepared with cellulose itself or both cellulose and polymer by click reactions. In addition, click reaction could be proved by fluorescence labeling for cellulose, and cellulose nanofibrils with multi-color fluorescent labelling could be prepared through two click reaction. In terms of hemicellulose and lignin research, the copolymer of xylan and polylactic acid was formed by click reaction. The glass transition temperature of the copolymer was lower than that of xylan, and the thermal decomposition temperature of the copolymer was higher than that of xylan. The triazole-linked xylosides and xylobiosides could be achieved through CuAAC reaction. A thermoplastic polymer could be prepared with lignin and polystyrene by click reaction. In addition, bioorthogonal click chemistry could be commissioned to visualize the plant cell wall lignification process. The application of click chemistry in lignocellulose has been very few, there is much more to do. Because click reaction condition is mild so that many reactions can be conducted at room temperature, it is very conducive to the research in the field of biomedical materials. What is more, cellulose and hemicellulose has good biocompatibility so that favorable conditions are created for the application of cellulose and hemicellulose in the biological field. In addition, copper-free click reactions may be as an important development direction due to the toxic effects of copper catalyst, such as strain-promoted alkyne-azide cycloaddition reaction, Thiol-Ene/Yne click reaction and Diels-Alder click reaction.

Key words: click chemistry, cellulose, hemicellulose, lignin

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