Methyl cellulose
[CAS# 9004-67-5]

Identification

• Classification: API >> Special medicine >> Ophthalmic medication
• Name: Methyl cellulose
• Synonyms: Methyl ether cellulose
• CAS Registry Number: 9004-67-5
• EC Number: 618-391-7
• SMILES: N(C)(C)c1cc(c(cc1)C(N)CC)C

Properties

• Solubility: water: 20 mg/mL (Expl.)

Safety Data

• Hazard Symbols: GHS07 Warning
• Hazard Statements: H302-H315-H319-H335
• Precautionary Statements: P261-P280-P301+P312-P302+P352-P305+P351+P338

Discovory and Applicatios

Methyl cellulose is a chemically modified cellulose ether in which some of the hydroxyl groups on the glucose units of the cellulose polymer are substituted with methoxy groups (–OCH₃). This non-ionic cellulose derivative is synthesized by treating cellulose with methyl chloride in the presence of an alkaline medium. The degree of substitution (DS), defined as the average number of substituted hydroxyl groups per glucose unit, typically ranges from 1.4 to 2.2 in commercial products. Methyl cellulose is water-soluble, forms clear gels and films, and is widely used in industrial, pharmaceutical, and food applications.

The development of methyl cellulose dates back to the early 20th century when researchers sought to create cellulose derivatives with improved solubility and processing properties. Native cellulose is insoluble in water and most organic solvents due to its extensive hydrogen bonding network. The introduction of methoxy groups interrupts this network, rendering the polymer soluble in cold water and giving rise to new physical and chemical behaviors. Methyl cellulose was one of the earliest cellulose ethers to be commercialized and has since become a key excipient in various industries.

One of the most distinctive features of methyl cellulose is its thermogelling property. In aqueous solution, it remains fluid at low temperatures but forms a gel upon heating. This reversible gelation occurs due to the aggregation of hydrophobic methoxy groups at elevated temperatures, resulting in a three-dimensional gel network. The temperature at which gelation occurs depends on the concentration, molecular weight, and degree of substitution of the polymer. This property is exploited in diverse applications, including controlled-release drug delivery systems and thermal-responsive materials.

In the pharmaceutical field, methyl cellulose is used as a binder in tablet formulations, a suspending agent in liquid dosage forms, and a viscosity modifier in topical preparations. It serves as a film-former in tablet coatings and a gelling agent in ophthalmic and nasal formulations. Its water solubility, non-toxicity, and inertness make it suitable for use in oral, topical, and ophthalmic drug products. In controlled-release matrices, methyl cellulose can slow the release of active ingredients by forming a hydrated gel layer upon contact with gastrointestinal fluids.

Methyl cellulose is also approved as a food additive (E461) and is used as a thickener, emulsifier, and stabilizer in food products. It improves texture, moisture retention, and shelf life in baked goods, sauces, and processed foods. In gluten-free baking, methyl cellulose helps to mimic the viscoelastic properties of gluten, contributing to dough structure and gas retention during baking. It is tasteless, odorless, and resistant to digestion in the human gastrointestinal tract.

In industrial applications, methyl cellulose is used as a thickener and film-forming agent in paints, coatings, adhesives, inks, and construction materials such as tile adhesives and cement-based mortars. In the cosmetics industry, it is employed as a viscosity modifier and stabilizer in creams, lotions, shampoos, and gels. Its compatibility with both aqueous and alcohol-based systems enhances its versatility in product formulations.

Methyl cellulose is available in various viscosity grades, typically ranging from low (e.g., 15 mPa·s) to high (e.g., 100,000 mPa·s), measured in 2% aqueous solutions at 20°C. The viscosity is influenced by the polymer’s molecular weight and degree of substitution, allowing manufacturers to tailor the rheological properties of formulations for specific end uses.

In biomedical research and biotechnology, methyl cellulose is used in cell culture as a semi-solid medium for colony formation assays and cell encapsulation. Its ability to form viscous solutions and gels under controlled conditions supports its use in tissue engineering and drug screening platforms.

In summary, methyl cellulose is a widely used cellulose ether known for its cold-water solubility, thermogelling behavior, and film-forming properties. It plays essential roles in pharmaceuticals, food technology, cosmetics, construction materials, and scientific research. Its chemical stability, biocompatibility, and versatility make it a valuable excipient and functional ingredient across many fields.

References

2025. Stimuli-responsive, methyl cellulose-based, interpenetrating network hydrogels: Non-covalent design, injectability, and controlled release. Carbohydrate Polymers, 347(1).
DOI: 10.1016/j.carbpol.2024.122689

2024. Gelation and post-gelation mechanism of methylcellulose in an aqueous medium: 1H NMR and dynamic compressive rheological studies. International Journal of Biological Macromolecules, 281(3).
DOI: 10.1016/j.ijbiomac.2024.137725

1979. Tear Film Breakup Time Prolonged With Unmedicated Cellulose Polymer Inserts. Archives of Ophthalmology, 97(10).
DOI: 10.1001/archopht.1979.01020020392026