纤维素纳米晶端醛还原的区域选择性修饰及丝光,ACS Sustainable Chemistry & Engineering

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纤维素纳米晶端醛还原的区域选择性修饰及丝光
ACS Sustainable Chemistry & Engineering ( IF 7.1 ) Pub Date : 2023-03-09 , DOI: 10.1021/acssuschemeng.2c07713
Lei Tan ₁ , Alain Dufresne ₂ , Ge Zhu ₁ , Ning Lin ₁

Affiliation

近年来，具有异质基团的纤维素纳米晶体 (CNC) 的还原端和与表面化学不同的反应性引起了人们的极大兴趣，这有助于开发针对这种天然生物质构建块的区域选择性修饰和性能定制的新策略。然而，对还原端所涉及现象的理解仍处于纤维素链的研究阶段，通常以溶解形式存在于溶剂中，但缺乏对以悬浮液形式存在的纳米晶体的广泛研究。本研究探讨了两个问题。第一个是对CNC还原端引入醛基的各种条件和参数的综合分析。第二个研究了末端改性物质对丝光过程中纳米晶体晶体重构的影响。对九种纳米纤维素样品进行了还原端醛基含量的定量测量，为在CNCs的还原端获得更多可用的醛基提供了科学依据，用于未来的研究。此外，在还原端对四种具有不同化学结构和宏观性质的 CNCs 进行了改性，并研究了它们在丝光过程中重组为 II 型纳米晶体。结果表明，末端物质的空间位阻对纳米晶体的晶体重构具有关键影响，为这种永恒的纳米材料的可能分子结构和不对称修饰提供了灵感。

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Regioselective Modification at Reducing End Aldehydes of Cellulose Nanocrystals and Mercerization

Receiving considerable interest in recent years, the reducing ends of cellulose nanocrystals (CNCs) with heterogeneous groups and different reactivity from surface chemistry contribute to the development of new strategies for regioselective modification and performance tailoring for this building block of natural biomass. However, the understanding of the phenomena involved at the reducing end is still at the research stage for cellulose chains, usually in dissolved form in a solvent, but lacks extensive investigation for nanocrystals, existing in the form of suspensions. Two issues are explored in this study. The first one concerns the comprehensive analysis of various conditions and parameters for the introduction of aldehyde groups at the reducing end of CNCs. The second investigates the influence of end-modified species on the crystalline reconfiguration of nanocrystals during mercerization. Quantitative measurements of the content of reducing end aldehyde groups are carried out for nine nanocellulose samples, offering scientific evidence to obtain more aldehyde groups available at the reducing end of CNCs for future studies. Furthermore, four species of CNCs with various chemical structures and macroscopic properties are modified at the reducing ends, and their reorganization as type-II nanocrystals during mercerization is investigated. The results indicate a critical effect of the steric hindrance of end species on the crystalline reconfiguration of nanocrystals, providing inspiration for a possible molecular structure and asymmetric modification for this ageless nanomaterial.

更新日期：2023-03-09

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