纳米纤维素:多层次跨尺度无机功能体系的构筑平台

Nanocellulose: A Sustainable Platform for Functional Materials Organization

现代工业的迅猛发展在为生活带来诸多便利的同时也危及人类赖以生存的生态环境.利用可再生资源,效仿生物材料的构筑特征及构效关系,建立可持续构筑途径,实现功能定向构筑已成为材料研究的重要推手及重大挑战.纳米纤维素来源于自然存储量最丰富的纤维素,是纤维素分子的自组装体,以手性、化学可修饰性、机械增强以及自组装等特性引起科学界的极大关注.结合纳米纤维素的本征矿化能力、基于化学组装与化学合成协同作用的辅助矿化以及基于生物合成协同矿化等途径,建立跨尺度多级结构的构建方法,开发高效纳米纤维素基无机功能材料研究具有重要的科学和社会意义.本综述针对纳米纤维素的矿化能力,围绕矿化驱动力、矿化选择性、异质矿化、跨尺度结构化、功能集成、功能定向构筑等重要科学问题,选择代表性纤维素基无机材料进行分析归纳,为推进多层次跨尺度纳米纤维素基无机功能体系的精准构筑提供科学依据.

Understanding how complex inorganic materials are organized through synergistic self-assembly and chemical synthesis across multiple length scale using nanocellulose is of growing interest in materials science and nanotechnology. This review article highlights recent advances in the synthetic construction of nanocellulosebased inorganic materials. We first examine a range of inorganic cations that give rise to inorganics-coated nanocellulose. It shows that nanocellulose binds preferentially to the inorganic cations in the order of hard base ≥borderline base >> soft base, indicating the formation of stable acid-base pairs between the surface hydroxyl oxygen of nanocellulose and the hard base closely followed by the borderline base. We then look into approaches that facilitate the nucleation, growth and transformation of inorganics surrounding nanocellulose. It is demonstrated that extended length scale structuration is possible, which warrants functional enhancement and renders new functionality for nanocellulose-based inorganic materials. Examples of function-led organization of nanocellulose-based inorganic materials were presented. Of particular interest are cellulose nanocrystals that facilitates its use as a chiral nano-mesogen for helicoidal organization with circular polarization ability, bacterial cellulose that promotes its applications as an optical sensing platform and cellulose nanofibers that exploit its potential as conductive substrates for water splitting. Ongoing research continues to exploit the richness of nanocellulose as a sustainable platform for rational organization of functional inorganic materials.