CMC (E466)

CMC (E466) or cellulose gum is a cellulose derivative with carboxymethyl groups (-CH2-COOH) bound to some of the hydroxyl groups of the glucopyranose monomers that make up the cellulose backbone. It is often used as its sodium salt, CMC (E466). CMC (E466) used to be marketed under the name Tylose, a registered trademark of SE Tylose.

CAS No. : 9000-11-7
EC Number:  618-378-6
IUPAC Name: sodium;2,3,4,5,6-pentahydroxyhexanal;acetate
Molecular Formula: C8H15NaO8

Other names:
Carboxymethylcellulose; CMC; carmellose; E466; cmc; CARBOXYL METHYL CELLULOSE; Croscarmellose sodium; Hydroxypropyl cellulose; Methyl cellulose; Tylose; Carboxymethylcellulose sodium salt; CMC (E466); Carboxymethylcellulose sodium; Aquaplast; Carmethose; Cellofas; Cellpro; Cellufresh; Cellugel; Celluvisc; Collowel; Ethoxose; Lovosa; Carmellose gum; Camellose gum; Cellulose gum; Sarcell tel; Cellofas B; Cellofas C; Cellogel C; Cellogen PR; Glikocel TA; CMC sodium salt; Edifas B; Nymcel S; Tylose C; Blanose BWM; Lovosa TN; Nymcel slc-T; Tylose CB series; Tylose CR; Unisol RH; Cellofas B5; Cellofas B6; Cellogen 3H; Sodium CMC; Tylose DKL; Carbose 1M; Cellogen WS-C; Majol PLX; Sodium cellulose glycolate; Cellofas B50; Courlose F 4; Courlose F 8; Polyfibron 120; Tylose CBR series; Avicel RC/CL; Fine Gum HES; NaCm-cellulose salt; Courlose F 20; Sodium CM-cellulose; Sodium carboxymethylcellulose; Copagel PB 25; Sanlose SN 20A; Cellufix FF 100; Courlose A 590; Courlose A 610; Courlose A 650; Courlose F 370; Modocoll 1200; Nymcel ZSB 10; Nymcel ZSB 16; Tylose CBS 30; Tylose CBS 70; Tylose CR 50; Tylose 666; Tylose C 30; Blanose BS 190; SODIUM CMC (E466); AC-Di-sol. NF; Carmellose sodium; Lucel (polysaccharide); Tylose CBR 400; Courlose F 1000G; Tylose C 300; Tylose C 600; Tylose CB 200; Daicel 1150; Daicel 1180; Orabase; Tylose C 1000P; B 10 (Polysaccharide); Carboxymethylcellulose sodium salt; CM-Cellulose sodium salt; Cellulose sodium glycolate; Sodium glycolate cellulose; CMC 7MT; Sodium carboxmethylcellulose; CMC (E466), sodium salt; CMC 3M5T; 7H3SF; CMC 2; CCRIS 3653; Cellulose carboxymethyl ether sodium salt; S 75M; Cellulose glycolic acid, sodium salt; Sodium salt of carboxymethylcellulose; B 10; Carmellose sodium, low-substituted; Cellulose, carboxymethyl ether; Aquacel; Cellulose carboxymethyl ether, sodium salt; Carboxymethylcellulose sodium [USP]; Croscarmellose sodium; Cellulose, carboxymethyl ether, sodium salt, low-substituted; CMC; Lovosa 20alk.; Carboxymethylcellulose Sodium [USAN]; CARBOXYMETHYLCELLULOSE SODIUM, LOW-SUBSTITUTED

CMC (E466)
Preparation of CMC (E466)
CMC (E466) is synthesized by the alkali-catalyzed reaction of cellulose with chloroacetic acid. The polar (organic acid) carboxyl groups render the cellulose soluble and chemically reactive.

Following the initial reaction, the resultant mixture produces about 60% CMC (E466) plus 40% salts (sodium chloride and sodium glycolate). This product is the so-called technical CMC (E466) which is used in detergents.

A further purification process is used to remove these salts to produce the pure CMC (E466) used for food, pharmaceutical, and dentifrice (toothpaste) applications. An intermediate "semipurified" grade is also produced, typically used in paper applications such as restoration of archival documents.

The functional properties of CMC (E466) depend on the degree of substitution of the cellulose structure (i.e., how many of the hydroxyl groups have taken part in the substitution reaction), as well as the chain length of the cellulose backbone structure and the degree of clustering of the carboxymethyl substituents.

Uses of CMC (E466)
CMC (E466) is used in food as a viscosity modifier or thickener, and to stabilize emulsions in various products including ice cream.
CMC (E466) is also a constituent of many non-food products, such as toothpaste, laxatives, diet pills, water-based paints, detergents, textile sizing, reusable heat packs, and various paper products.

CMC (E466) is used primarily because it has high viscosity, is nontoxic, and is generally considered to be hypoallergenic as the major source fiber is either softwood pulp or cotton linter. CMC (E466) is used extensively in gluten free and reduced fat food products.

In laundry detergents, CMC (E466) is used as a soil suspension polymer designed to deposit onto cotton and other cellulosic fabrics, creating a negatively charged barrier to soils in the wash solution. CMC (E466) is used as a lubricant in artificial tears.

CMC (E466) is also used as a thickening agent, for example, in the oil-drilling industry as an ingredient of drilling mud, where it acts as a viscosity modifier and water retention agent. CMC (E466) for example, is used as a negative control agent for alopecia in rabbits.

Knitted fabric made of cellulose (e.g. cotton or viscose rayon) may be converted into CMC (E466) and used in various medical applications.

Device for epistaxis (nose bleeding). A poly-vinyl chloride (PVC) balloon is covered by CMC (E466) knitted fabric reinforced by nylon. The device is soaked in water to form a gel, this is inserted into the nose and the balloon inflated. The combination of the inflated balloon and the therapeutic effect of the CMC (E466) stops the bleeding.

Fabric used as a dressing following ear nose and throat surgical procedures.
Water is added to form a gel, and this gel is inserted into the sinus cavity following surgery.
Insoluble microgranular CMC (E466) is used as a cation-exchange resin in ion-exchange chromatography for purification of proteins.

Presumably, the level of derivatization is much lower, so the solubility properties of microgranular cellulose are retained, while adding sufficient negatively charged carboxylate groups to bind to positively charged proteins.

CMC (E466) is also used in ice packs to form a eutectic mixture resulting in a lower freezing point, and therefore more cooling capacity than ice.

Aqueous solutions of CMC (E466) have also been used to disperse carbon nanotubes. The long CMC (E466) molecules are thought to wrap around the nanotubes, allowing them to be dispersed in water. In conservation-restoration, it is used as an adhesive or fixative (commercial name Walocel, Klucel).

CMC (E466) is used to achieve tartrate or cold stability in wine. This innovation may save megawatts of electricity used to chill wine in warm climates. CMC (E466) is more stable than metatartaric acid and is very effective in inhibiting tartrate precipitation.

CMC (E466) is reported that KHT crystals, in presence of CMC (E466), grow slower and change their morphology. Their shape becomes flatter because they lose 2 of the 7 faces, changing their dimensions. CMC (E466) molecules, negatively charged at wine pH, interact with the electropositive surface of the crystals, where potassium ions are accumulated.

The slower growth of the crystals and the modification of their shape are caused by the competition between CMC (E466) molecules and bitartrate ions for binding to the KHT crystals (Cracherau et al. 2001).

In veterinary medicine, CMC (E466) is used in abdominal surgeries in large animals, particularly horses, to prevent the formation of bowel adhesions.

CMC (E466) is sometimes used as an electrode binder in advanced battery applications (i.e. lithium ion batteries), especially with graphite anodes. CMC (E466)'s water solubility allows for less toxic and costly processing than with non-water-soluble binders, like the traditional polyvinylidene fluoride (PVDF), which requires toxic n-methylpyrrolidone (NMP) for processing. CMC (E466) is often used in conjunction with styrene-butadiene rubber (SBR) for electrodes requiring extra flexibility, e.g. for use with silicon-containing anodes.

Culinary uses of CMC (E466)
CMC (E466) powder is widely used in the ice cream industry, to make ice creams without churning or extreme low temperatures, thereby eliminating the need for the conventional churners or salt ice mixes. CMC (E466) is used in preparing bakery products such as bread and cake. The use of CMC (E466) gives the loaf a much improved quality at a reduced cost to the baker, by economizing on the fat component.

CMC (E466) is also used as an emulsifier in high quality biscuits. By dispersing fat uniformly in the dough, it improves the release of the dough from the moulds and cutters, achieving well-shaped biscuits without any distorted edges. It can also help to reduce the amount of egg yolk or fat used in making the biscuits, thus achieving economy.

Use of CMC (E466) in candy preparation ensures smooth dispersion in flavour oils, and improves texture and quality. CMC (E466) is used in chewing gums, margarines and peanut butter as an emulsifier. It is also used in leather crafting to burnish the edges.

Enzymology of CMC (E466)
CMC (E466) has also been used extensively to characterize enzyme activity from endoglucanases (part of the cellulase complex). CMC (E466) is a highly specific substrate for endo-acting cellulases, as its structure has been engineered to decrystallize cellulose and create amorphous sites that are ideal for endoglucanase action. CMC (E466) is desirable because the catalysis product (glucose) is easily measured using a reducing sugar assay, such as 3,5-dinitrosalicylic acid.

Using CMC (E466) in enzyme assays is especially important in regard to screening for cellulase enzymes that are needed for more efficient cellulosic ethanol conversion. However, CMC (E466) has also been misused in earlier work with cellulase enzymes, as many had associated whole cellulase activity with CMC (E466) hydrolysis.

As the mechanism of cellulose depolymerization has become better understood, exo-cellulases are dominant in the degradation of crystalline (e.g. Avicel) and not soluble (e.g. CMC (E466)) cellulose.

Adverse reactions of CMC (E466)
While thought to be uncommon, case reports of severe reactions to CMC (E466) exist. In one such instance, a woman was known to experience anaphylaxis following exposure. Skin testing is believed to be a useful diagnostic tool for this purpose.

Effects on inflammation, microbiota-related metabolic syndrome, and colitis are a subject of research. CMC (E466) has been found to cause inflammation of the gut, altering microbiota, and was found to be a triggering factor of inflammatory bowel diseases such as ulcerative colitis and Crohn's disease.

CMC (E466) is an internally cross-linked sodium carboxymethylcellulose for use as a superdisintegrant in pharmaceutical formulations.
E468 is the E number of crosslinked CMC (E466), used in food as an emulsifier.

Background
The cross-linking reduces water solubility while still allowing the material to swell (like a sponge) and absorb many times its weight in water. As a result, it provides superior drug dissolution and disintegration characteristics, thus improving formulas′ subsequent bioavailability by bringing the active ingredients into better contact with bodily fluids.

CMC (E466) also resolves formulators′ concerns over long-term functional stability, reduced effectiveness at high tablet hardness levels, and similar problems associated with other products developed to enhance drug dissolution. It is a very commonly used pharmaceutical additive approved by the U.S. Food and Drug Administration.

Its purpose in most tablets – including dietary supplements – is to assist the tablet in disintegrating in the gastrointestinal tract promptly. If a tablet disintegrating agent is not included, the tablet could disintegrate too slowly, in the wrong part of the intestine or not at all, thereby reducing the efficacy and bioavailability of the active ingredients.

Croscarmellose is made by first soaking crude cellulose in sodium hydroxide, and then reacting the cellulose with sodium monochloroacetate to form sodium carboxymethylcellulose. Excess sodium monochloroacetate slowly hydrolyzes to glycolic acid and the glycolic acid catalyzes the cross-linkage to form CMC (E466). Chemically, it is the sodium salt of a cross-linked, partly O-(carboxymethylated) cellulose.
CMC (E466) was first used as a stabilizer in horse supplements.

Chemistry
CMC (E466) is an ether of cellulose in which some of the hydroxyl groups in the repeating glucose units have been hydroxypropylated forming -OCH2CH(OH)CH3 groups using propylene oxide. The average number of substituted hydroxyl groups per glucose unit is referred to as the degree of substitution (DS).

Complete substitution would provide a DS of 3. Because the hydroxypropyl group added contains a hydroxyl group, this can also be etherified during preparation of CMC (E466). When this occurs, the number of moles of hydroxypropyl groups per glucose ring, moles of substitution (MS), can be higher than 3.

Because cellulose is very crystalline, CMC (E466) must have an MS about 4 in order to reach a good solubility in water. CMC (E466) has a combination of hydrophobic and hydrophilic groups, so it has a lower critical solution temperature (LCST) at 45 °C. At temperatures below the LCST, CMC (E466) is readily soluble in water; above the LCST, CMC (E466) is not soluble.

CMC (E466) forms liquid crystals and many mesophases according to its concentration in water. Such mesophases include isotropic, anisotropic, nematic and cholesteric. The last one gives many colors such as violet, green and red.

Uses
Lacrisert, manufactured by Aton Pharma, is a formulation of CMC (E466) used for artificial tears. It is used to treat medical conditions characterized by insufficient tear production such as keratoconjunctivitis sicca), recurrent corneal erosions, decreased corneal sensitivity, exposure and neuroparalytic keratitis. CMC (E466) is also used as a lubricant for artificial eyes. In pharmaceuticals it is used as a binder in tablets.

CMC (E466) is used as a sieving matrix for DNA separations by capillary and microchip electrophoresis.
CMC (E466) is the main ingredient in Cellugel, which is used in book conservation. Cellugel is described as "A safe, penetrating consolidant for leather book covers affected by red rot" and is produced by Preservation Solutions.

Uses of CMC (E466)
CMC (E466) has a wide range of uses.

Medical
Constipation
CMC (E466) is used to treat constipation. Effects generally occur within three days. It is taken by mouth and is recommended with sufficient water. Side effects may include abdominal pain. CMC (E466) is classified as a bulk forming laxative. It works by increasing the amount of stool present which improves intestinal contractions.

CMC (E466) is available over the counter. It is sold under the brand name Citrucel among others.

Artificial tears and saliva
The lubricating property of CMC (E466) is of particular benefit in the treatment of dry eyes. Solutions containing CMC (E466) or similar cellulose derivatives are used as substitute for tears or saliva if the natural production of these fluids is disturbed.

Medication manufacturing
CMC (E466) is used in the manufacture of drug capsules; its edible and nontoxic properties provide a vegetarian alternative to the use of gelatin.
Consumer products of CMC (E466)
Thickener and emulsifier

CMC (E466) is very occasionally added to hair shampoos, tooth pastes and liquid soaps, to generate their characteristic thick consistency. This is also done for foods, for example ice cream or croquette.
CMC (E466) is also an important emulsifier, preventing the separation of two mixed liquids because it is an emulsion stabilizer.
CMC (E466) is also used as paint rheological modifier to prevent paint sagging.

Lubricant
CMC (E466) may be used in personal lubricant.

Construction materials of CMC (E466)
CMC (E466) finds a major application as a performance additive in construction materials. It is added to mortar dry mixes to improve the mortar's properties such as workability, open and adjustment time, water retention, viscosity, adhesion to surfaces etc.

Construction grade CMC (E466) is not to be identified with food and pharmaceutical grade CMC (E466) and hydroxypropyl CMC (E466), as it may be cross-linked with glyoxal for easy dispersion in water.

The construction materials can be cement-based or gypsum-based. Notable examples of dry mixture mortars which utilize CMC (E466) include tile adhesives, EIFS, insulating plasters, hand-troweled and machine-sprayed plaster, stucco, self-leveling flooring, extruded cement panels, skim coats, joint & crack fillers, and tile grouts. Typical usage is about 0.2% – 0.5% of total dry powder weight for dry mixtures.

Derivatives of CMC (E466) which improve performance characteristics include hydroxypropyl CMC (E466) (HPMC) and hydroxyethyl CMC (E466) (HEMC). These derivatives typically improve the characteristics such as water retention, vertical surface slip resistance, open time, etc.

Glue and binder
CMC (E466) can be employed as a mild glue which can be washed away with water. This may be used in the fixing of delicate pieces of art as well as in book conservation to loosen and clean off old glue from spines and bookboards.

CMC (E466) is the main ingredient in many wallpaper pastes. It is also used as a binder in pastel crayons and also as a binder in medications.

Paper and textile sizing
CMC (E466) is used as sizing in the production of papers and textiles as it protects the fibers from absorbing water or oil.

Cell culture
CMC (E466) is also used in cell culture to study viral replication. It is dissolved in the same nutrient-containing medium in which cells are normally grown. A single layer of cells is grown on a flat surface, then infected with a virus for a short time. The strength of the viral sample used will determine how many cells get infected during this time.

The thick CMC (E466) medium is then added on top of the cells in place of normal liquid medium. As the viruses replicate in the infected cells, they are able to spread between cells whose membranes touch each other, but are trapped when they enter the CMC (E466).

Only cells closely neighboring an infected cell will become infected and die. This leaves small regions of dead cells called plaques in a larger background of living uninfected cells. The number of plaques formed is determined by the strength of the original sample.

Bacterial and protozoal motility inhibitor
Aqueous CMC (E466) solutions have been used to slow bacterial and protozoal cell motility for closer inspection. Changing the amount of CMC (E466) in solution permits the adjustment of the solution's viscosity.

Stem cell differentiation
CMC (E466) is used in the most common approaches to quantify multiple or single lineage-committed hematopoietic progenitors, called colony-forming cells (CFCs) or colony-forming units (CFUs), in combination with culture supplements that promote their proliferation and differentiation, and allow the clonal progeny of a single progenitor cell to stay together and thus form a colony of more mature cells.

Chemistry
It is a hydrophilic white powder in pure form and dissolves in cold (but not in hot) water, forming a clear viscous solution or gel.

CMC (E466) is used as a buffer additive in capillary electrophoresis to control electroosmotic flow for improved separations.

Special effects
The slimy, gooey appearance of an appropriate preparation of CMC (E466) with water, in addition to its nontoxic, nonallergenic, and edible properties, makes it popular for use in special effects for motion pictures and television wherever vile slimes must be simulated. In the film Ghostbusters, the gooey substance the supernatural entities used to "slime" the Ghostbusters was mostly a thick water solution of CMC (E466). The Aliens ooze and drip a great deal of CMC (E466)—especially the queen.

CMC (E466) has been used to safely simulate molten materials, as well. In several of the Terminator films, it was back-lit with colored gels and films to reproduce the heated glow of iron in the large pouring ladles used to transport the metal from the smelting ovens to the various molds and forms. CMC (E466) was also a stand-in for the lava flows in Los Angeles in Volcano and on the volcanic surface of Mustafar, in Star Wars: Episode III – Revenge of the Sith.

Chemistry
CMC (E466) does not occur naturally and is synthetically produced by heating cellulose with caustic solution (e.g. a solution of sodium hydroxide) and treating it with methyl chloride. In the substitution reaction that follows, the hydroxyl residues (-OH functional groups) are replaced by methoxide (-OCH3 groups).

Different kinds of CMC (E466) can be prepared depending on the number of hydroxyl groups substituted. Cellulose is a polymer consisting of numerous linked glucose molecules, each of which exposes three hydroxyl groups. The Degree of Substitution (DS) of a given form of CMC (E466) is defined as the average number of substituted hydroxyl groups per glucose. The theoretical maximum is thus a DS of 3.0, however more typical values are 1.3–2.6.

Different CMC (E466) preparations can also differ in the average length of their polymer backbones.

Solubility and temperature
CMC (E466) has a lower critical solution temperature (LCST) between 40 °C and 50 °C. At temperatures below the LCST, it is readily soluble in water; above the LCST, it is not soluble, which has a paradoxical effect that heating a saturated solution of CMC (E466) will turn it solid, because CMC (E466) will precipitate out. The temperature at which this occurs depends on DS-value, with higher DS-values giving lower solubility and lower precipitation temperatures because the polar hydroxyl groups are masked.

Preparing a solution of CMC (E466) with cold water is difficult however: as the powder comes into contact with water, a gel layer forms around it, dramatically slowing the diffusion of water into the powder, hence the inside remains dry. A better way is to first mix the powder with hot water, so that the CMC (E466) particles are well dispersed (and so have a much higher effective surface area) in the water, and cool down this dispersion while stirring, leading to the much more rapid dissolution of those particles.

Carboxymethylcellulose
Carboxymethylcellulose (CMC) is an anionic, water-soluble cellulose derivative. Solubility of CMC (E466) depends on the DP as well as the degree of substitution and the uniformity of the substitution distribution. Water solubility of CMC (E466) would increase with decreased DP and increased carboxymethyl substitution and substitution uniformity. The viscosity of the solution increases with increasing DP and increasing concentration.

CMC (E466) is soluble in water at any temperature. Because of its highly hygroscopic nature, CMC (E466) hydrates rapidly. Rapid hydration may cause agglomeration and lump formation when the CMC (E466) powder is introduced into water. Lump creation can be eliminated by applying high agitation while the powder is added into the water or preblending the CMC (E466) powder with other dry ingredients such as sugar before adding into water.

Due to its high solubility and clarity of its solutions, CMC (E466) is commonly used in beverages and beverage dry mixes to provide rich mouthfeel. It is also used in acidified protein drinks to stabilize protein and prevent it from precipitating. CMC (E466) is also added to syrup and sauce formulations to increase viscosity.

Bakery is another application where CMC (E466) is commonly used to improve the quality and the consistency of the end product. In tortilla breads, for example, it is used to improve the process ability of the dough and the textural properties of the end product, including foldability and rollability.

CMC (E466) is a derivative of cellulose, containing carboxymethyl groups that are generated via the reaction of cellulose with chloroacetate in alkali to produce substitutions in the C2, C3, or C6 positions of glucose units (Gelman, 1982). As a result, CMC (E466) is water soluble and more amenable to the hydrolytic activity of cellulases.

CMC (E466) is therefore a useful additive to both liquid and solid medium for the detection of cellulase activity, and its hydrolysis can be subsequently determined by the use of the dye Congo red, which binds to intact β-d-glucans. Zones of clearing around colonies growing on solid medium containing CMC (E466), subsequently stained with Congo red, provides a useful assay for detecting hydrolysis of CMC (E466) and therefore, β-d-glucanase activity (Teather and Wood, 1982).

The inoculation of isolates onto membrane filters placed on the surface of CMC (E466) agar plates is a useful modification of this technique, as the filter may subsequently be removed allowing visualization of clear zones in the agar underneath cellulolytic colonies.

CMC (E466)
CMC (E466) is the sodium salt of CMC (E466), an anionic derivative. It is widely used in oral, ophthalmic, injectable, and topical pharmaceutical formulations. For solid dosage forms, it is used primarily as a binder or matrix former.

Pharmaceutical grades of CMC (E466) are available commercially at degree of substitution (DS) values of 0.7, 0.9, and 1.2, with a corresponding sodium content of 6.5%–12% wt. It is also available in several different viscosity grades. CMC (E466) is highly soluble in water at all temperatures, forming clear solutions. Its solubility depends on its degree of substitution.

CMC (E466), when used as a binder, yields softer granules that have good compressibility, forming tough tablets of moderate strength. CMC (E466), being highly hygroscopic, can absorb a large quantity of water (> 50%) at elevated relative humidity conditions. Hence, the tablets tend to harden with age.

Cellulose Ethers
CMC (E466) is the major cellulose ether. By activating the noncrystalline regions of cellulose, selective regions of alkylating reagents can attack the cellulose. This is termed the concept of reactive structure fractions and is used widely for the production of CMC (E466).

Another route for carrying out the same reaction is by derivatization of cellulose in reactive microstructures, formed by induced phase separation. This process involves the usage of NaOH in anhydrous state in combination with solvents like DMA/LiCl. These CMC (E466) products have a distribution of substituents that deviate significantly from statistical prediction of the product theoretically.

CMC (E466) is used in several drug delivery and tissue engineering purposes. The release of apomorphine, a drug used to regulate motor responses in Parkinson’s disease, was successfully incorporated into CMC (E466) powder formulation and exhibited a sustained nasal release, and performed better than starch-based delivery vehicle. CMC (E466) has been used successfully in gastrointestinal drug delivery. Hence, CMC (E466) is seen as a successful drug delivery system for mucosal tissue. Apart from drug delivery, CMC (E466) is useful as a scaffold in tissue engineering.

CMC (E466) hydrogels having pH-dependent swelling characteristics were capable of releasing entrapped drug at the right pH present in the tissue of interest and showed great potential as a wound dressing material. CMC (E466) hydrogels could be used for encapsulating cells of nucleus pulposis and hence are a potential replacement for intervertebral disk degeneration. CMC (E466) has been combined with chitosan and hydroxyapatite for bone and dental regeneration purposes too.

CMC (E466)/silk fibroin/graphene oxide films
CMC (E466), a derivative of cellulose, is a cheaper, nontoxic, biodegradable, and renewable polymer. The drawback of CMC (E466) film is its poor mechanical properties. Due to its superior mechanical properties, low flammability, impressive biocompatibility, and greater biodegradability, silk fibroin has been identified as a potentially convenient biomaterial.

Depending on the requirements for various applications it can be modified to a hydrogel, film, scaffold, or nonwoven mat. GO is a suitable filler in composites that enhances the mechanical properties. Abdulkhani et al. synthesized biopolymer nanocomposite films by mixing reduced graphene oxide (RGO) to CMC (E466) /silk fibroin matrix. The result showed that RGO is useful for composites due to its high performance and low cost. These nanocomposites are used in food packaging.

CMC (E466) and hydroxyethyl cellulose cross-linked with divinyl sulphone have been used to remove body fluids during surgery and to collect body fluids in the treatment of edema. The polymer biocompatibility is also promising in diuretic therapy. CMC (E466) and hydroxyethyl cellulose as well as poly(ethylene glycols) of different molecular weights have been used in developing orally administrable hydrogels for water absorption.98 High capacity super water absorbents were injected intracerebrally for studying hypothalamic areas in controlling the female production cycle.

CMC (E466) is used for its thickening and swelling properties in a wide range of complex formulated products for pharmaceutical, food, home, and personal care applications, as well as in paper, water treatment, and mineral processing industries. To design Na CMC (E466) solutions for applications, a detailed understanding of the concentration-dependent rheology and relaxation response is needed. We address this here by investigating aqueous Na CMC (E466) solutions over a wide range of concentrations using rheology as well as static and dynamic light scattering.

The concentration dependence of the solution specific viscosities ηsp could be described using a set of three power laws, as predicted from the scaling theory of polyelectrolytes. Alternatively, a simpler approach could be used, which interpolates between two power law regimes and introduces only one characteristic crossover concentration. We interpret the observed behavior as a transition from the semidilute nonentangled to the entangled concentration regimes; this transition behavior was not observed in the solution structure, as determined using static light scattering. Dynamic light scattering revealed three relaxation modes.

The two fastest relaxations were assigned as the “fast” and “slow” relaxation modes typically observed in salt-free or not fully screened polyelectrolyte solutions within the semidilute concentration range. The third, typically weak mode, was attributed to the presence of a small amount of poorly dissolved cellulose residuals. Since filtration altered the solution behavior, without sufficiently removing the residuals, data collection and processing were adapted to account for this, which facilitated a detailed light scattering investigation of the original solutions, relevant for industrial applications.

The relaxation time characterizing the fast mode, τf, was concentration independent; whereas the relaxation time of the slow mode, τs, demonstrated similar crossover behavior as observed for the specific viscosity, further demonstrating the dynamic nature of the crossover.

CMC (E466) is an anionic water soluble polymer based on renewable cellulosic raw material. It functions as rheology modifier, retains water and is an excellent film former. These attributes make it a preferred choice as a bio-based hydrocolloid in multiple applications.

Properties and Applications
CMC (E466), also known as cellulose gum or Tylose, and its sodium salt are important cellulose derivatives. The bound carboxymethyl groups (-CH2-COOH) along the polymer chain makes the cellulose water-soluble.

When dissolved, it increases the viscosity of aqueous solutions, suspensions and emulsions, and at higher concentration, it provides pseudo-plasticity or thixotropy. As a natural polyelectrolyte, CMC (E466) imparts a surface charge to neutral particles and thus, can be used to improve the stability of aqueous colloids and gels or to induce agglomeration.

CMC (E466) is used in many products including adhesives, sealants, coatings, textiles, ceramics, mining products, building and construction materials, laundry detergents, pulp, paper, and tobacco. It functions as a dispersant agent, emulsifier, stabilizer, water retainer, thickener and clarifying agent. Or it is used as a film-forming and binding agent, for example to agglomerate and bind iron ore into pellets.

Since CMC (E466) is physiologically harmless2, it is also widely used in the food, cosmetic, and pharmaceutical industries. In food products, it acts as a thickener, stabilizer and binder and helps to control crystallization, moisture retention, and fat uptake. In cosmetic products such as creams and lotions, it thickens and stabilizes the product and improves its moisturising effect. And in tooth pastes it is added to adjust the viscosity profile.