纤维素Cellulose

β-1,4 连接使相邻葡萄糖单元交替翻转 180°，形成伸直的带状长链。每个单元有三个羟基，链内和链间形成大量氢键，使分子链平行排列成高度结晶的微纤丝，强度可与钢相比。因此纤维素不溶于水和一般有机溶剂，只溶于铜氨溶液、离子液体、NaOH/尿素等特殊体系。人体缺乏能水解 β-1,4 键的纤维素酶，所以不能消化纤维素，而反刍动物依靠瘤胃微生物分解它。

β-1,4 linkage flips each glucose 180° relative to the next, giving straight, ribbon-like chains. Each unit has three hydroxyls, and dense intra- and interchain hydrogen bonding packs the chains into highly crystalline microfibrils as strong, weight for weight, as steel. Cellulose is therefore insoluble in water and ordinary solvents, dissolving only in special systems such as cuprammonium, ionic liquids or NaOH–urea. Humans lack the cellulases that cleave β-1,4 bonds and cannot digest it, while ruminants rely on gut microbes.

1838 年法国化学家佩扬从植物组织中分离出这种物质并命名为 cellulose。1846 年舍恩拜因用硝酸处理棉花制得硝化纤维（火棉）；1870 年海厄特以硝化纤维和樟脑制成赛璐珞，是最早的半合成塑料。1892 年克罗斯和贝文发明黏胶法生产人造丝。1920 年代施陶丁格以纤维素等为例确立了高分子概念。

In 1838 the French chemist Payen isolated the substance from plant tissue and named it cellulose. In 1846 Schönbein treated cotton with nitric acid to make nitrocellulose (guncotton), and in 1870 Hyatt made celluloid from nitrocellulose and camphor, the first semi-synthetic plastic. Cross and Bevan invented the viscose process for rayon in 1892. In the 1920s Staudinger used cellulose among his examples in establishing the concept of macromolecules.

纤维素以木材、棉花和麻的形式用于建筑、纺织和造纸。化学改性得到醋酸纤维（香烟滤嘴、胶片）、硝化纤维（炸药、清漆）、羧甲基纤维素（增稠剂）和再生纤维素（黏胶、莱赛尔纤维、玻璃纸）。纳米纤维素和纤维素乙醇是生物质高值化利用的研究热点。

As wood, cotton and bast fibres cellulose serves building, textiles and paper. Chemical modification gives cellulose acetate (cigarette filters, film), nitrocellulose (explosives, lacquers), carboxymethyl cellulose (thickener) and regenerated cellulose (viscose, lyocell, cellophane). Nanocellulose and cellulosic ethanol are active areas in adding value to biomass.