纤维素的功能化

综述近年来纤维素功能化和功能材料的发展情况,介绍了通过化学改性、特殊物理加工、表面改性等获得纤维素功能的功能的各种功能化的主最新的功能设计思路,并介绍了纤维素功能材料的应用,未来潜在的应用领域和发展前景。     

基于纤维素的先进功能材料

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.     

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。     

邻苯二亚胺纤维素的合成及性质

邻苯二亚胺纤维素的合成及性质叶君熊犍梁文芷（华南理工大学轻化工研究所广州５１０６４１）关键词邻苯二亚胺纤维素荧光合成中图分类号Ｏ６３６．１１，ＴＱ３５２．９纤维素化学反应是纤维素化学改性和功能材料合成的基础。以往纤维素化学反应的研究工作大多集中于其分...     

以醋酸纤维素吸水胶囊为载体制备固定化脲酶

把高吸水材料封在具超滤功能的醋酸纤维素（CA）皮膜中，制成胶囊。此胶囊浸泡在脲酶水溶液中，水分受高吸水材料的吸引透过皮膜进入胶囊中，脲酶被截留在CA皮膜上，并且与CA上的活性基团相结合，形成CA胶囊固定化脲酶。     

纤维素基气凝胶型吸油材料的研究进展

近年来,开发"绿色"、可回收的高效吸油材料吸引了国内外学者的广泛关注.纤维素基气凝胶兼具多孔气凝胶型材料比表面积大、孔隙率高的特点以及纤维素材料天然、可再生的优势,对其进行表面疏水化处理后,是一种极具发展潜力的环保型吸油材料.本文分别系统综述了再生纤维素基气凝胶型、天然纤维素基气凝胶型及细菌纤维素基气凝胶型吸油材料的研究进展,并对它们的制备方法和吸油性能进行了归纳总结,最后讨论了当前纤维素基气凝胶型吸油材料研究中存在的问题和今后的研究方向.     

珠状纤维素的制备及其应用

珠状纤维素是一种新型的可反应性高分子材料，在生化物质的分离、纯化，生物工程和其他领域有良好的应用前景。本文系统地回顾了珠状纤维素的制备方法，对珠状纤维素的应用研究也作了简要介绍。     

纤维素在新型绿色溶剂离子液体中的溶解及其应用*

近年来,离子液体作为一种极具应用前景的绿色溶剂受到越来越多的关注。纤维素是自然界中含量最丰富的可再生资源,必将成为未来最重要的工业原料之一。离子液体在纤维素化学领域的应用遵循了绿色化学中开发环境友好溶剂和利用生物可再生资源为原料这两个基本原则,大大拓展了纤维素的工业应用前景,为纤维素资源的绿色应用提供了一个崭新的平台。本文对纤维素在离子液体中溶解的研究进展及其在制备再生纤维素材料、纤维素衍生物及生物乙醇等方面的应用进行了综述。纤维素大分子的降解机理及其控制途径、纤维素晶态结构变化规律及其调控途径、纤维素与固体反应试剂的均相衍生化体系的建立及提高衍生化效率的途径等基础问题仍需要进一步深入研究。     

以纤维素材料为基质的降解塑料的研究进展

本文详述了以天然高分子纤维素材料为基质的降解塑料的发展。纤维素材料由于其来源丰富,有良好的反应性,优异的生物降解性,无毒性等,因而可用来制备降解塑料．其开发和应用是解决目前世界范围内的“白色污染”的一条理想途径．     

Deoxycelluloses and related structures

The syntheses of various deoxycelluloses and related structures (cellulosenes and anhydrocelluloses) from the mid‐1920s to the present are critically reviewed. General synthetic strategies to prepare deoxycelluloses include nucleophilic displacement of good leaving groups. Distinctions are made between reaction of cellulosics under homogeneous and heterogeneous conditions. Recent advances in the preparation of halodeoxycelluloses have led to high degree of substitution fluorodeoxycelluloses and bromodeoxycelluloses. Applications for the deoxycelluloses are numerous and characterized by biological, chemical or physical end uses.     

Chiroptical properties of an alternatingly functionalized cellotriose bearing two porphyrin groups

Right-handedness derived from bisporphyrins attached to a cellotriose backbone at O-6 and O'-6 positions is revealed for the first time. This cellotriose is proposed as a model of alternatingly functionalized cellulosics, which have promising properties for applications in optoelectronics and molecular receptors owing to the chirality and rigid backbone effects.     

5.6 Cellulose acetate in separation technology

Cellulose acetate has been utilized in a variety of separation and purification processes. In membrane separation, cellulosics, in particular cellulose acetate, have played important roles. Hemodialysis and desalination are the established fields where acetate membranes have been applied. Recently, a new application, that is the purification of drinking water, is growing. The history of cellulosic membranes, preparation of acetate membranes, and applications will be reviewed. Cellulose acetate is also useful in chromatography and related separation technologies. These application will also be reviewed and the relationship between the superstructure of cellulose triacetate and its adsorptive behavior is briefly mentioned.     

Chemical modification of the surface of cellulosic fibres. 2. Introduction of alkenyl moieties via condensation reactions involving isocyanate functions

Various cellulosic substrates including powders, long fibres and sheets were treated with isocyanates bearing an alkenyl function in a non-swelling medium. These heterogeneous reactions introduced a small but significant number of polymerizable moieties at the surface of the cellulose. In a second step, the free radical polymerization of styrene or methyl methacrylate was carried out in the presence of these modified cellulosics. It was shown that the alkenyl functions appended onto their surface took part in the chain growth thus giving a continuous path of covalent bonds between the solid substrate and the polymer matrix. 0969--0239 © 1998 Blackie Academic & Professional     

Flexible, all-organic chemiresistor for detecting chemically aggressive vapors

Chemiresistors made of thin films of single-walled carbon nanotube (CNT) bundles on cellulosics (paper and cloth) can detect aggressive oxidizing vapors such as nitrogen dioxide and chlorine at 250 and 500 ppb, respectively, at room temperature in ambient air without the aid of a vapor concentrator. Inkjet-printed films of CNTs on 100% acid-free paper are significantly more robust than dip-coated films on plastic substrates. Performance attributes include low sensor-to-sensor variation, spontaneous signal recovery, negligible baseline drift, and the ability to bend the sensors to a crease without loss of sensor performance.     

Novel Orientation Techniques for the Preparation of High-Performance Materials from Semiflexible Polymers

Abstract

A technique is described for postponing the formation of anisotropic domains in semiflexible polymers so as to better orient them along a common direction. A theory has been developed to provide a foundation for this approach and guidance on carrying it out experimentally, and is described in outline form. The primary advantage of this processing route is the improved mechanical properties accompanying the increased orientation. This is illustrated by increases in moduli and ultimate properties of films of some cellulosics, polyisocyanates, and the protein collagen in the form of gelatin.     

Cellulose-p-toluenesulfonates: A valuable intermediate in cellulose chemistry

Organo-soluble cellulose-p-toluenesulfonates (tosylates) with an insignificant incorporation of chlorodeoxy functions were prepared by reacting cellulose dissolved in N,N-dimethyl acetamide/LiCl and used as intermediates in the design of cellulosics with new, unusual molecular structures. Thus, the remaining OH groups were acylated and sulfated yielding products with controlled lipophily and amphiphily which are promising polymers for self-organizing systems. The polarity reversal by tosylation was used for C-substitution reactions. The molecular structures of the products were proved by FTIR, ¹H- and ¹³C-NMR spectroscopy.     

Effect of a nonionic surfactant on Trichoderma cellulase treatments of regenerated cellulose and cotton yarns

It has been shown that some surfactants affect the hydrolysis of cellulose by cellulase. In this study, the effect of the surfactant Tween 20 on the hydrolysis of different cellulosic fibers was investigated and related to the cellulose fiber structure. It was found that this non-ionic surfactant enhanced the enzymatic saccharification of highly crystalline cellulosics such as Avicel, Tencel and cotton but not of cuprammonium rayon. The enhanced saccha-rification effected by the surfactant is attributed to inhibition of non-productive sorption of the endoglucanase of the cellulose surface which gives greater access to the cellulose chain ends by the exoglucanase. Although all three fibers lost tensile strength as a result of the enzymatic treatment, no further decrease was effected by the presence of the surfactant.     

Effect of freeze-dried immobilized cells on delignified cellulosic material in low-temperature and ambient-temperature wine making

In this article, were port on wine making by freeze-dried immobilized cells on delignified cellulosic material for ambient and low temperatures. Biocatalyst supported by freeze-dried delignified cellulosic (FDC) material recovered after the first repeated-batch fermentations the fermentation efficiency and startup, which become about equal to those of biocatalyst supported by wet delignified cellulosic material. The FDC biocatalyst was suitable for wine making at low temperatures (5–15°C), and produced wine of 12% alcoholic degree, with the main volatiles contained in the wine and reduced by a decrease in temperature. The fermentation efficiency was not affected by total acidity of must, while an increase in initial Be density improved percentages of higher alcohols and ethylacetate. The quality of the wine was validated by a preliminary taste test to be in the range of acceptable to excellent.