Methyl cellulose

Methyl cellulose

Names
Other names Cellulose, methyl ether; methylated cellulose; methylcellulose; E461
Identifiers
CAS Number	9004-67-5 Y
ChemSpider	none
PubChem CID	Methylcellulose
UNII	4GFU244C4J Y
Properties
Chemical formula	variable
Molar mass	variable
Pharmacology
1=ATC code }}	A06AC06 (WHO)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YN ?)
Infobox references

Methylcellulose (or methylcellulose) is a compound derived from cellulose. It is sold under a variety of trade names and is used as a thickener and emulsifier in various food and cosmetic products, and also as a bulk-forming laxative. Like cellulose, it is not digestible, non-toxic, and not an allergen. In addition to culinary uses, it is used in arts and crafts such as papier-mâché and is often the main ingredient of wallpaper paste.

Methyl cellulose has a wide range of uses.

Methylcellulose is used to treat constipation and is classified as a bulk forming laxative.^[1] It works by increasing the amount of stool present which improves intestinal contractions.^[1][2] Effects generally occur within three days.^[1] It is taken orally with sufficient water.^[2] Side effects may include abdominal pain.^[2]

It is available over the counter.^[1] It is sold under the brand name Citrucel among others.^[1]

The lubricating property of methylcellulose is of particular benefit in the treatment of dry eyes.^[3] Solutions containing methyl cellulose or similar cellulose derivatives are used as substitute for tears or saliva if the natural production of these fluids is disturbed.

Methylcellulose is 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^[4] or croquette. Methylcellulose also prevents the separation of emulsions because it is an emulsion stabilizer.

The E number of methylcellulose as food additive is E461. E464 is hydroxypropyl methylcellulose^[5], which is more soluble in water.^[6]

Methylcellulose, as a gel, has the unique property of setting when hot and melting when cold.^[7]

In some meat analogues that are intended to replicate the texture of meat, methylcellulose is used as an ingredient, typically in concentrations less than 2%.^[8][9]

Methyl cellulose finds a major application as a performance additive in construction materials.^[10] 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 methyl cellulose is not to be identified with food and pharmaceutical grade methyl cellulose and hydroxypropyl methyl cellulose, as it may be cross-linked with glyoxal for easy dispersion in water.

Methyl cellulose 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. Hydroxypropyl methylcellulose (HPMC) is an FDA-approved water-soluble adhesive, has been used in various wet-adhesion applications in construction products, paints, and drug delivery for 70 years. HPMC adheres strongly to all wet surfaces, regardless of hydrophobicity.^[11]

Hydroxypropyl methyl cellulose (HPMC) and hydroxyethyl methyl cellulose (HEMC) are used as binders in dust control technologies. They mitigate fugitive dust released in arid and semi-arid areas as well as improve commercial face masks when used in the filtering material.^[12]

Methyl cellulose 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 methyl cellulose 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 methyl cellulose. 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.^[13]

Pure methyl cellulose is highly resistant to ageing and is therefore ideal for preserving art and cultural artefacts^[14].^[15] It can be used to stabilise powdered paint layers and to bond paint layers, frames, wood, textiles, etc. in liquid, foam^[16] or mesh form. Not to be confused with hydroxypropyl cellulose (e.g. Klucel ®), which has lower ageing resistance and is much more plastic.

The slimy, gooey appearance of an appropriate preparation of methyl cellulose 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 methyl cellulose.^[17] The Aliens ooze and drip a great deal of methyl cellulose—especially the queen.^[18]

Methyl cellulose 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. Methyl cellulose 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.{{citation needed|date=October 2016}

Methyl cellulose 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 methyl cellulose will turn it solid, because methyl cellulose 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.^{[citation needed]} Preparing a solution of methyl cellulose 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 methyl cellulose 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.^[19]

• Carboxymethyl cellulose
• Ethyl cellulose
• Ethyl methyl cellulose
• Hydroxypropyl cellulose
• Hydroxyethyl cellulose

• Cathleen Baker (1984). Methylcellulose & Sodium Carboxymethylcellulose: An Evaluation for Use in Paper Conservation through Accelerated Aging. Preprints of the Contributions to the Paris Congress, 2–8 September 1984: Adhesives and Consolidants, pp. 55–59. International Institute of Conservation.
• Robert L. Feller and Myron H. Wilt (1990) (free fulltext). Evaluation of Cellulose Ethers for Conservation. Getty Conservation Institute. http://www.getty.edu/publications/virtuallibrary/0892360992.html?imprint=gtcn&pg=3&res=20. 
• Pijper A (March 1947). "Methylcellulose and Bacterial Motility". J. Bacteriol. 53 (3): 257–69. doi:10.1128/JB.53.3.257-269.1947. PMID 16561270. 

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