基于纤维素的先进功能材料（专题报道）

 收集整理了近几年间发表在国内外重要期刊上的约360篇文献,以纤维素功能材料的制备方法为线索,简要综述了该领域的最新进展,对纤维素基纤维材料、膜材料、光电材料、杂化材料、智能材料、生物医用材料等功能材料的制备过程、功能和应用前景做了概括性描述.     

纤维素模板可控制备功能纳米材料的研究进展

作为自然界中最丰富的天然高分子材料,纤维素具备无毒无害、可再生、价格低廉和多层次空间结构等优点,被广泛应用在纺织、化学、可降解材料等领域。其中,纤维素特有的分子排列和多层次的空间结构,使其被广泛用作生物模板,进行可控制备功能纳米材料,纳米材料可以实现最大程度地复制出纤维素模板的纳米结构。本文综述了应用纤维素为模板,可控制备多种功能纳米材料(氧化物纳米材料、金属纳米材料、无机非金属复合纳米材料和其他无机纳米材料等)的最新进展,并展望了以纤维素模板可控制备功能纳米材料的未来研究方向。     

纤维素基功能材料的研究进展

纤维素是自然界中最为丰富的可再生天然高分子材料,价格低廉,可生物降解,是最有潜力的绿色材料之一。纤维素分子链上含有大量羟基,形成分子间与分子内强烈的氢键网络,使得纤维素难于溶解在普通的溶剂中,难于加工,极大地限制了它的广泛应用。本文从纤维素的衍生物、接枝共聚物及凝胶的制备三方面,介绍了纤维素基功能材料的研究进展情况。通过化学改性的方法,减弱了纤维素分子间的氢键作用,得到结构与功能多样的纤维素材料,拓宽了纤维素的应用领域。     

基于海鞘纤维素的先进功能材料研究进展

海洋生物质资源十分丰富,且具有多种功能基团,开发前景可观.其中,海鞘是一类能生产纤维素的海洋动物,而且其纤维素主要以纳米纤维形式存在.本文简要介绍海鞘纤维素结构及其构建的功能材料的研究进展,全面概述海鞘纤维素纳米晶体的制备、结构和形貌、力学性能以及悬浮液的性质和液晶行为.重点介绍海鞘纤维素纳米纤维在聚合物材料增强、仿生材料设计以及功能材料构建方面的应用.深入讨论生物医用、自修复、环境敏感、导电导热、分离等功能材料的构效关系.     

以纤维素/AmimCl溶液制备纤维素气凝胶

利用离子液体AmimCl溶解结合超临界CO2干燥的方法制备了纤维素气凝胶材料.研究了不同初始浓度的纤维素溶液及其在不同凝固浴中制备的纤维素凝胶的流变行为,进一步考察了纤维素溶液浓度和凝固浴种类对纤维素气凝胶材料结构的影响.结果表明,随着初始纤维素溶液浓度的增大,气凝胶的孔结构逐渐致密,比表面积随之减小;凝固浴的组成对纤维素气凝胶的结构也有较大影响.采用适当的制备条件,可以制备出高比表面积的纤维素气凝胶材料.对纤维素气凝胶的热性能进行了表征,结果表明所得到的气凝胶材料具有较好的热稳定性和较高的炭残余含量.     

利用离子液体制备纤维素基气凝胶

纤维素基气凝胶材料的研究在近年来吸引了人们极大的关注,这是因为这类新型材料具有通常无机气凝胶的典型结构特点,如超轻、高孔率、高比表面积等,同时具有天然生物质材料的原料丰富、可再生、可生物降解的优点。本文首先简要介绍了纤维素基气凝胶材料及其发展概况,进而主要介绍了以离子液体为溶剂制备再生纤维素基气凝胶的研究进展,包括纤维素基气凝胶的制备方法、结构及其功能性。最后对离子液体法制备的纤维素基气凝胶材料的前景进行了简要的展望。     

纤维素基印迹吸附剂的制备及研究性能

以纤维素为原料,1-乙烯基咪唑为最佳功能单体,2,4-二氯苯酚(2,4-DCP)作为模板分子,采用分子印迹技术结合原子转移自由基聚合方法,制备纤维素基印迹吸附材料。利用红外光谱(FT-IR)及扫描电镜(SEM)对材料的结构及性能进行了表征,并对纤维素印迹吸附剂的选择性吸附性能进行研究。     

微纳米纤维素功能膜在能源与环境领域的应用

探寻绿色清洁的资源与材料以维持高效的社会经济增长是未来数十年人们面临的最大挑战之一. 可持续资源与绿色材料的开发是降低传统化石能源与材料比重的最有前途的方案. 纤维素作为一种可持续发展、 可生物再生、 储量丰富且低成本的天然高分子聚合物, 在众多领域中具有广泛的应用, 并且纤维素可以加工成各种构型, 包括气凝胶、 泡沫、 海绵和薄膜等. 本文介绍了不同形态的纤维素及其衍生物组装而成的功能膜在能源与环境中的应用, 综述了微纳米纤维素及其衍生物在先进功能化储能器件方面的最新进展和制备方案, 以及在用于水处理的膜分离技术中的应用, 其中重点讨论了微纳米纤维素及其衍生物功能膜在电池、 电容器及水处理等领域中的作用, 如隔膜、 柔性电极膜和分离膜等. 此外, 还对纤维素及其衍生物功能膜的未来发展进行了总结和展望.     

纳米纤维素研究及应用进展Ⅰ

纳米纤维素是一种新型的高分子功能材料,具有独特的结构和优良的性能。特别是细菌纤维素,其三维纳米网状结构,生物适应性,良好的机械稳定性,抗菌性等优良性能使它越来越收到重视。本文介绍了近年来对于纳米纤维素制备和应用的研究进展,主要涉及细菌纤维素,植物纤维素和纤维素纳米复合物的制备。本文的下篇《纳米纤维素研究及应用进展Ⅱ》将继续介绍纳米纤维素在生物,医学,增强剂,造纸工业,净化,传导,与无机物复合,食品工业,磁性复合物等方面的应用。     

纳米纤维素的制备*

在纳米尺寸范围操控纤维素分子及其超分子聚集体,结构设计并组装出稳定的多重花样,由此创制出具有优异功能的新纳米精细化工品、新纳米材料,是纤维素科学的前沿领域和热点。为了研究当前制备纳米纤维素的现状和发展方向,简述了纳米纤维素化学基础,介绍了三类纳米纤维素：纳米纤维素晶体（晶须）、纳米纤维素复合物和纳米纤维素纤维,重点综述了纳米纤维素的五种制备方法：化学法制备纳米纤维素晶体和晶须、生物法制备细菌纤维素、物理法制备微纤化纳米纤维素、人工合成纳米纤维素和静电纺丝制备纤维素纤维,讨论了各种制备方法的优点和缺点,指出开展纳米纤维素超分子的可控结构设计、立体与位向选择性控制与制备、分子识别与位点识别等自组装过程机理、多尺度结构效应的形成机理等基础理论性研究是主要研究基础,新型的、绿色、低能耗、快速、高效的制备方法是纳米纤维素制备方法的发展方向。     

均相体系中纤维素化学改性研究概述

本文概述了近十年来纤维素在均相体系中化学改性的研究成果,重点介绍了纤维素在氯化锂/N,N-二甲基乙酰胺（LiCl/DMAc）、二甲基亚砜/三水合四丁基氟化铵（DMSO/TBAF3H2O）、离子液体、碱/尿素体系中的均相酯化、醚化以及接枝共聚合反应.同时,总结了纤维素在这些溶剂中的反应特性及其衍生化产物的结构、性质和应用.     

以离子液体为介质的纤维素加工与功能化

纤维素作为自然界中储量最大的天然高分子,被认为是未来世界能源与化工的主要原料.但由于分子链间存在丰富氢键网络以及高度结晶的聚集态结构特点,天然纤维素不熔化、难溶解,造成纤维素的加工极其困难,纤维素材料的传统生产工艺复杂且污染严重,极大限制了纤维素材料的广泛应用.近年来,人们发现一些特定结构的离子液体能够高效溶解纤维素,为纤维素的加工和功能化提供了新的多用途平台.本文从"溶解纤维素的离子液体、纤维素溶解机理与溶液性质、以离子液体制备再生纤维素材料和以离子液体为介质合成纤维素衍生物"4个方面详细介绍了本课题组在此领域的研究进展.     

The Electronic Nature of the 1,4‐β‐Glycosidic Bond and Its Chemical Environment: DFT Insights into Cellulose Chemistry

The molecular understanding of the chemistry of 1,4‐β‐glucans is essential for designing new approaches to the conversion of cellulose into platform chemicals and biofuels. In this endeavor, much attention has been paid to the role of hydrogen bonding occurring in the cellulose structure. So far, however, there has been little discussion about the implications of the electronic nature of the 1,4‐β‐glycosidic bond and its chemical environment for the activation of 1,4‐β‐glucans toward acid‐catalyzed hydrolysis. This report sheds light on these central issues and addresses their influence on the acid hydrolysis of cellobiose and, by analogy, cellulose. The electronic structure of cellobiose was explored by DFT at the BB1 K/6‐31++G(d,p) level. Natural bond orbital (NBO) analysis was performed to grasp the key bonding concepts. Conformations, protonation sites, and hydrolysis mechanisms were examined. The results for cellobiose indicate that cellulose is protected against hydrolysis not only by its supramolecular structure, as currently accepted, but also by its electronic structure, in which the anomeric effect plays a key role.     

Development of Bifunctional Catalysts for the Conversions of Cellulose or Cellobiose into Polyols and Organic Acids in Water

The efficient utilization of renewable lignocellulosic biomass has attracted much attention in recent years. One of the most desirable routes for the transformation of cellulose, the main component of lignocellulosic biomass, is to convert cellulose under mild conditions selectively into a value-added chemical or into a platform compound, which can be easily converted to versatile chemicals or fuels in the subsequent step. The activation of cellulose, typically starting by the cleavage of its glycosidic bonds, under mild conditions and the selective formation of a particular molecule are critical challenges. Bifunctional catalysts coupling the acid sites for the activation of the glycosidic bonds via hydrolysis and the metal nanoparticles for the hydrogenation or oxidation of glucose intermediate have shown promising performances for the conversion of cellulose or cellobiose into hexitols or gluconic acid in water under mild conditions. This short review has summarized some recent studies on the development of such bifunctional catalysts or catalytic systems. The following two kinds of bifunctional catalysts or catalytic systems have mainly been discussed: (1) a liquid acid in combination with a supported metal catalyst, (2) solid acid-supported metal nanoparticles. Emphases have been laid on the conversions of cellulose or cellobiose into sorbitol and gluconic acid catalyzed respectively by ruthenium and gold nanoparticles loaded on carbon nanotubes bearing acid sites.     

Polyoxometalates as efficient catalysts for transformations of cellulose into platform chemicals

Efficient utilisation of renewable biomass resources, particularly lignocellulosic biomass, for the production of chemicals and fuels has attracted much attention in recent years. The catalytic conversion of cellulose, the main component of lignocellulosic biomass, selectively into a platform chemical such as glucose, 5-hydroxymethyl furfural (HMF), sorbitol or gluconic acid under mild conditions is the most desirable route. Acid catalysis plays a crucial role in the conversion of cellulose via the cleavage of its glycosidic bonds. Owing to their unique features such as strong acidity, water-tolerance, low corrosiveness and recoverability, polyoxometalates have shown promising performances in transformations of cellulose into platform chemicals both in homogeneous and heterogeneous systems. This article highlights recent studies on polyoxometalates and polyoxometalate-based bifunctional catalysts or catalytic systems for the selective conversions of cellulose and cellobiose, a model molecule of cellulose, into platform chemicals.     

纤维素及其衍生物的高压静电纺丝

高压静电纺丝作为一种制备纳米纤维的先进技术,近年来受到普遍关注。而纤维素和纤维素衍生物由于其优越的性质已应用于各个领域。运用高压静电纺丝技术对纤维素及其衍生物进行研究,开拓了新的研究领域和发展方向。本文介绍了高压静电纺丝技术的研究背景和原理,总结了近几年研究者们在纤维素以及纤维素衍生物高压静电纺丝方面的工作进展,尤其对不同溶剂体系溶解纤维素用于静电纺丝的优缺点进行了比较,评述了这方面的前沿性探索研究,并对未来的发展进行了展望。     

生物吸附材料吸附水中砷的研究进展

砷是严重威胁人类健康的剧毒元素之一,近年来对砷的吸附研究成为人们关注的热点之一。壳聚糖、纤维素、微生物等生物吸附材料具有生产成本低、环境友好等优点,因而被作为新型的生物吸附材料得到广泛应用。本文综述了生物吸附材料在饮用水、地下水和工业废水处理中的应用研究,以及国内外的最新研究进展。     

Synthese et etude de celluloses echangeuses d'ions. Leur emploi dans l'epuration des eaux residuaires de l'industrie textile—1: Synthese d'une cellulose greffee par des chaines poly (acide acrylique) et d'une cellulose renfermant des fonctions ammonium quaternaire

For use as ion exchangers and particularly as purification agents for textile industrial effluents, cellulose grafted with polyacrylic acid and cellulose substituted by quaternary ammonium functions have been prepared. For both syntheses, the influences of experimental parameters have been studied in detail and the optimum conditions for large-scale preparation have been determined. Large amounts of modified cellulose have been obtained and tested in industry (cf. part III). The grafting by acrylic acid has been carried out by the ceric-ion method; the quaternary ammonium cellulose has been obtained by condensation of cellulose with epoxy propyl triethyl ammonium chloride. Synthesis of this salt in the presence of cellulose has been achieved so that the quaternary ammonium cellulose can be obtained from cellulose and epichlorhydrin in one step.     

Novel concepts of dissolving pulp production

Herein, we report about existing and novel dissolving pulp processes providing the basis for an advanced biorefinery. The SO₂–ethanol–water (SEW) process has the potential to replace the acid sulphite process for the production of rayon-grade pulps owing to a higher flexibility in the selection of the raw material source, substantially lower cooking times, and the near absence of sugar degradation products. Special attention is paid to developments that target toward the selective and quantitative fractionation of paper-grade pulps into hemicelluloses and cellulose of highest purity. This target has been accomplished by the IONCELL process where the entire hemicellulose fraction is selectively dissolved in an ionic liquid in which the H-bond basicity and acidity are adequately adjusted by the addition of a co-solvent. At the same time, pure hemicellulose can be recovered by further addition of the co-solvent, which then acts as a non-solvent. The residual pure cellulose fraction may then enter a Lyocell process for the production of regenerated cellulose products.