Department of Bioproducts and Biosystems, Aalto University, P.O. Box 16300, FI-00076 Aalto, Espoo, Finland.
Adolphe Merkle Institute, Université de Fribourg, Chemin des Verdiers 4, CH-1700, Fribourg, Switzerland.
Angew Chem Int Ed Engl. 2021 Jan 4;60(1):66-87. doi: 10.1002/anie.202002433. Epub 2020 Sep 9.
Native plant cellulose has an intrinsic supramolecular structure. Consequently, it can be isolated as nanocellulose species, which can be utilized as building blocks for renewable nanomaterials. The structure of cellulose also permits its end-wise modification, i.e., chemical reactions exclusively on one end of a cellulose chain or a nanocellulose particle. The premises for end-wise modification have been known for decades. Nevertheless, different approaches for the reactions have emerged only recently, because of formidable synthetic and analytical challenges associated with the issue, including the adverse reactivity of the cellulose reducing end and the low abundance of newly introduced functionalities. This Review gives a full account of the scientific underpinnings and challenges related to end-wise modification of cellulose nanocrystals. Furthermore, we present how the chemical modification of cellulose nanocrystal ends may be applied to directed assembly, resulting in numerous possibilities for the construction of new materials, such as responsive liquid crystal templates and composites with tailored interactions.
天然植物纤维素具有内在的超分子结构。因此，它可以被分离为纳米纤维素物质，可作为可再生纳米材料的构建块。纤维素的结构还允许其进行端基修饰，即纤维素链或纳米纤维素颗粒的一端上的化学反应。端基修饰的前提条件已经存在了几十年。然而，由于与该问题相关的艰巨的合成和分析挑战，包括纤维素还原端的反应性差和新引入官能团的低丰度，最近才出现了不同的反应方法。本综述全面介绍了与纤维素纳米晶的端基修饰相关的科学基础和挑战。此外，我们还介绍了如何将纤维素纳米晶末端的化学修饰应用于定向组装，从而为构建新材料（如响应性液晶模板和具有定制相互作用的复合材料）提供了许多可能性。
