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Cellulose is an organic compound with the chemical formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of glycosidic bond glucose units. Cellulose is an important structural component of the primary cell wall of green plants, many forms of algae and the . Some species of bacteria secrete it to form . Cellulose is the most abundant biopolymer on Earth. The cellulose content of cotton fibre is 90%, that of wood is 40–50%, and that of dried hemp is approximately 57%.Cellulose. (2008). In Encyclopædia Britannica. Retrieved January 11, 2008, from Encyclopædia Britannica Online. Chemical Composition of Wood. . ipst.gatech.edu.Piotrowski, Stephan and Carus, Michael (May 2011) Multi-criteria evaluation of lignocellulosic niche crops for use in biorefinery processes . nova-Institut GmbH, Hürth, Germany.
Cellulose is mainly used to produce paperboard and paper. Smaller quantities are converted into a wide variety of derivative products such as cellophane and rayon. Conversion of cellulose from into such as cellulosic ethanol is under development as a renewable fuel source. Cellulose for industrial use is mainly obtained from wood pulp and cotton. Cellulose is also greatly affected by direct interaction with several organic liquids.
Some animals, particularly and , can digestion cellulose with the help of symbiosis micro-organisms that live in their guts, such as Trichonympha. In human nutrition, cellulose is a non-digestible constituent of insoluble dietary fiber, acting as a hydrophilic bulking agent for human feces and potentially aiding in defecation.
Cellulose is derived from Glucose units, which condense through β(1→4)-. This linkage motif contrasts with that for α(1→4)-glycosidic bonds present in starch and glycogen. Cellulose is a straight chain polymer. Unlike starch, no coiling or branching occurs and the molecule adopts an extended and rather stiff rod-like conformation, aided by the equatorial conformation of the glucose residues. The multiple hydroxyl on the glucose from one chain form with oxygen atoms on the same or on a neighbour chain, holding the chains firmly together side-by-side and forming microfibrils with high tensile strength. This confers tensile strength in where cellulose microfibrils are meshed into a polysaccharide matrix. The high tensile strength of plant stems and of the tree wood also arises from the arrangement of cellulose fibers intimately distributed into the lignin matrix. The mechanical role of cellulose fibers in the wood matrix responsible for its strong structural resistance, can somewhat be compared to that of the reinforcement bars in concrete, lignin playing here the role of the cement acting as the "glue" in between the cellulose fibres. Mechanical properties of cellulose in primary plant cell wall are correlated with growth and expansion of plant cells. Live fluorescence microscopy techniques are promising in investigation of the role of cellulose in growing plant cells.
Compared to starch, cellulose is also much more crystallinity. Whereas starch undergoes a crystalline to amorphous solid transition when heated beyond 60–70 °C in water (as in cooking), cellulose requires a temperature of 320 °C and pressure of 25 MPa to become amorphous in water.
Several types of cellulose are known. These forms are distinguished according to the location of hydrogen bonds between and within strands. Natural cellulose is cellulose I, with structures Iα and Iβ. Cellulose produced by bacteria and algae is enriched in Iα while cellulose of higher plants consists mainly of Iβ. Cellulose in regenerated cellulose fibers is cellulose II. The conversion of cellulose I to cellulose II is irreversible, suggesting that cellulose I is Metastability and cellulose II is stable. With various chemical treatments it is possible to produce the structures cellulose III and cellulose IV. Structure and morphology of cellulose by Serge Pérez and William Mackie, CERMAV-CNRS, 2001. Chapter IV.
Many properties of cellulose depend on its chain length or degree of polymerization, the number of glucose units that make up one polymer molecule. Cellulose from wood pulp has typical chain lengths between 300 and 1700 units; cotton and other plant fibers as well as bacterial cellulose have chain lengths ranging from 800 to 10,000 units. Molecules with very small chain length resulting from the breakdown of cellulose are known as ; in contrast to long-chain cellulose, cellodextrins are typically soluble in water and organic solvents.
The chemical formula of cellulose is (C6H10O5)n where n is the degree of polymerization and represents the number of glucose groups.
Plant-derived cellulose is usually found in a mixture with hemicellulose, lignin, pectin and other substances, while bacterial cellulose is quite pure, has a much higher water content and higher tensile strength due to higher chain lengths.
Cellulose consists of fibrils with crystalline and amorphous solid regions. These cellulose fibrils may be individualized by mechanical treatment of cellulose pulp, often assisted by chemical oxidation or enzyme treatment, yielding semi-flexible nanocellulose generally 200 nm to 1 μm in length depending on the treatment intensity. Cellulose pulp may also be treated with strong acid to hydrolization the amorphous fibril regions, thereby producing short rigid nanocellulose a few 100 nm in length. These are of high technological interest due to their self-assembly into liquid crystal, production of or , use in with superior thermal and mechanical properties, and use as Pickering stabilizers for emulsions.
RTCs contain at least three different cellulose synthases, encoded by CesA ( Ces is short for "cellulose synthase") genes, in an unknown stoichiometry. Separate sets of CesA genes are involved in primary and secondary cell wall biosynthesis. There are known to be about seven subfamilies in the plant CesA superfamily, some of which include the more cryptic, tentatively-named Csl (cellulose synthase-like) enzymes. These cellulose syntheses use UDP-glucose to form the β(1→4)-linked cellulose.
Bacterial cellulose is produced using the same family of proteins, although the gene is called BcsA for "bacterial cellulose synthase" or CelA for "cellulose" in many instances. In fact, plants acquired CesA from the endosymbiosis event that produced the chloroplast. All cellulose synthases known belongs to glucosyltransferase family 2 (GT2).
Cellulose synthesis requires chain initiation and elongation, and the two processes are separate. Cellulose synthase ( CesA) initiates cellulose polymerization using a steroid primer, beta-sitosterol-beta-glucoside, and UDP-glucose. It then utilises UDP-D-glucose precursors to elongate the growing cellulose chain. A cellulase may function to cleave the primer from the mature chain.
Cellulose is also synthesised by tunicate animals, particularly in the tests of (where the cellulose was historically termed "tunicine" (tunicin)).
Most mammals have limited ability to digest dietary fibre such as cellulose. Some like cows and sheep contain certain symbiosis anaerobic bacteria (such as Cellulomonas and Ruminococcus species) in the flora of the rumen, and these bacteria produce called that hydrolyze cellulose. The breakdown products are then used by the bacteria for proliferation. The bacterial mass is later digested by the ruminant in its digestive system (stomach and small intestine). use cellulose in their diet by fermentation in their hindgut. Some contain in their certain flagellate protozoa producing such enzymes, whereas others contain bacteria or may produce cellulase.
The enzymes used to the glycosidic linkage in cellulose are glycoside hydrolases including endo-acting and exo-acting . Such enzymes are usually secreted as part of multienzyme complexes that may include and carbohydrate-binding modules.
Semi-crystalline cellulose polymers react at pyrolysis temperatures (350–600 °C) in a few seconds; this transformation has been shown to occur via a solid-to-liquid-to-vapor transition, with the liquid (called intermediate liquid cellulose or molten cellulose) existing for only a fraction of a second. Glycosidic bond cleavage produces short cellulose chains of two-to-seven monomers comprising the melt. Vapor bubbling of intermediate liquid cellulose produces aerosols, which consist of short chain anhydro-oligomers derived from the melt.
Continuing decomposition of molten cellulose produces volatile compounds including levoglucosan, , , light oxygenates, and gases via primary reactions. Within thick cellulose samples, volatile compounds such as levoglucosan undergo 'secondary reactions' to volatile products including pyrans and light oxygenates such as glycolaldehyde.
The most important solubilizing agent is carbon disulfide in the presence of alkali. Other agents include Schweizer's reagent, N-methylmorpholine N-oxide, and lithium chloride in dimethylacetamide. In general, these agents modify the cellulose, rendering it soluble. The agents are then removed concomitant with the formation of fibers. (2025). 9789525216035, Fapet OY. ISBN 9789525216035 Cellulose is also soluble in many kinds of ionic liquids.
The history of regenerated cellulose is often cited as beginning with George Audemars, who first manufactured regenerated nitrocellulose fibers in 1855. (2025). 9780471440260, Wiley-Interscience. ISBN 9780471440260 Although these fibers were soft and strong -resembling silk- they had the drawback of being highly flammable. Hilaire de Chardonnet perfected production of nitrocellulose fibers, but manufacturing of these fibers by his process was relatively uneconomical. In 1890, L.H. Despeissis invented the cuprammonium process – which uses a cuprammonium solution to solubilize cellulose – a method still used today for production of artificial silk. (2025). 9781855734593, The Textile Institute. ISBN 9781855734593 In 1891, it was discovered that treatment of cellulose with alkali and carbon disulfide generated a soluble cellulose derivative known as viscose. This process, patented by the founders of the Viscose Development Company, is the most widely used method for manufacturing regenerated cellulose products. Courtaulds purchased the patents for this process in 1904, leading to significant growth of viscose fiber production. By 1931, expiration of patents for the viscose process led to its adoption worldwide. Global production of regenerated cellulose fiber peaked in 1973 at 3,856,000 tons.
Regenerated cellulose can be used to manufacture a wide variety of products. While the first application of regenerated cellulose was as a clothing textile, this class of materials is also used in the production of disposable medical devices as well as fabrication of artificial membranes.
Ester derivatives include:
| Organic esters | Organic acids | H or −(C=O)CH3 |
| −(C=O)CH3 | ||
| H or −(C=O)CH2CH3 | ||
| H or −(C=O)CH3 or −(C=O)CH2CH3 | ||
| H or −(C=O)CH3 or −(C=O)CH2CH2CH3 | ||
| Inorganic esters | Inorganic acids | H or −NO2 |
| H or −SO3H |
Cellulose acetate and cellulose triacetate are film- and fiber-forming materials that find a variety of uses. Nitrocellulose was initially used as an explosive and was an early film forming material. When plasticized with camphor, nitrocellulose gives celluloid.
Cellulose Ether derivatives include:
| Alkyl | E461 | |
| E462 | ||
| E465 | ||
| Hydroxyalkyl | ||
| E463 | ||
| E464 | ||
| E467 | ||
| E466 |
The sodium carboxymethyl cellulose can be cross-linked to give the croscarmellose sodium (E468) for use as a Excipient in pharmaceutical formulations. Furthermore, by the covalent attachment of thiol groups to cellulose ethers such as sodium carboxymethyl cellulose, ethyl cellulose or hydroxyethyl cellulose Mucoadhesion and permeation enhancing properties can be introduced. Thiolated cellulose derivatives (see ) exhibit also high binding properties for metal ions.
Another possible application is as .
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