Carboxymethyl cellulose (CMC) is an important natural thickener, which is widely used in food, medicine, cosmetics, oil extraction and other fields. As a multifunctional additive, CMC has good thickening, stabilization, film-forming, moisturizing and other properties. Compared with other thickeners, CMC’s unique structure and properties make it stand out in many applications.

1. Chemical structure

Carboxymethyl cellulose
Carboxymethyl cellulose is an anionic cellulose ether made by introducing carboxymethyl groups into natural cellulose after alkalization. Its basic structural unit is glucose, and carboxymethyl replaces part of the hydroxyl groups (-OH) in cellulose to form a carboxymethyl ether bond (-O-CH2-COOH). This structure makes CMC have high solubility in water and good rheological properties.

Other thickeners
Xanthan gum: Xanthan gum is a high molecular weight polysaccharide produced by fermentation of Xanthomonas. Its main chain is composed of β-D-glucan, and its side chains contain mannose, glucuronic acid, etc. Xanthan gum has high viscosity and excellent shear thinning properties.

Guar Gum: Guar gum is extracted from the endosperm of guar beans and belongs to galactomannan. The main chain is composed of D-mannose and the side chain is D-galactose. Guar gum is easily soluble in cold water and forms a high-viscosity colloid.

Pectin: Pectin is a polysaccharide present in plant cell walls, mainly composed of galacturonic acid, and its methoxylation degree affects its functional properties. Pectin has good gel properties in an acidic environment.

Hydroxypropyl Methylcellulose (HPMC): HPMC is a derivative of methylcellulose with a partially hydroxypropylated and methylated structure. HPMC has good solubility and thickening properties in water.

2. Thickening mechanism

Carboxymethyl cellulose
After CMC is dissolved in water, the carboxymethyl group makes it have good hydrophilicity, and interacts with water molecules by forming hydrogen bonds and van der Waals forces. Its thickening mechanism is mainly to increase the viscosity of the solution through the entanglement and repulsion between molecules. In addition, CMC has good stability under acidic or alkaline conditions and is widely used in systems with different pH values.

Other thickeners
Xanthan gum: Xanthan gum increases the viscosity of the solution through the entanglement and hydrogen bonding of long-chain molecules. Its unique shear thinning property causes the viscosity to decrease rapidly when subjected to shear force, and restores high viscosity when stationary.

Guar gum: Guar gum increases the viscosity of the solution by forming a cross-linked network and swelling by water absorption. Its molecular structure can form a highly viscous colloidal system.

Pectin: Pectin forms hydrogen bonds with water molecules through the carboxyl groups of its side chains. It can form a gel network with calcium ions under acidic conditions, significantly increasing the viscosity of the solution.

Hydroxypropyl methylcellulose: HPMC increases the viscosity of the solution through the entanglement of molecules and the formation of hydrogen bonds. Its solubility and viscosity vary greatly under different temperature conditions, and it has certain thermal gel properties.

3. Application Scope

Carboxymethyl Cellulose
Food Industry: CMC is commonly used in foods such as dairy products, bread, beverages, and jams to thicken, stabilize, moisturize, and improve texture.
Medicine: In the pharmaceutical field, CMC is used as a binder and disintegrant for tablets, and is also used in ophthalmic lubricants and ointment bases.
Cosmetics: CMC is used in cosmetics such as lotions and creams, and has moisturizing and stabilizing functions.
Petroleum Industry: In oil production, CMC is used in drilling fluids and muds to thicken and reduce filtration loss.
Other Thickeners
Xanthan Gum: Widely used in food, cosmetics, pharmaceuticals, and oilfield chemicals, especially for systems that require shear-thinning properties, such as sauces, sauces, and emulsifiers.
Guar Gum: Commonly used in foods such as ice cream, dairy products, and salad dressings to provide high viscosity and stability; used as a thickener and stabilizer in the papermaking and textile industries.
Pectin: Mainly used in foods such as jams, jellies, and soft candies, because of its gel properties, it performs well in high sugar and acidic environments.
Hydroxypropyl methylcellulose: used in pharmaceutical preparations, building materials, food additives, etc., especially in thermal gels and controlled-release drugs.

3. Safety

Carboxymethyl cellulose
CMC is widely regarded as a safe food additive and meets the food safety standards of many countries. When the amount used is in compliance with regulations, CMC is non-toxic to the human body. It also shows good biocompatibility and low allergenicity when used as a pharmaceutical excipient and cosmetic ingredient.

Other thickeners
Xanthan gum: As a food additive, xanthan gum is generally considered safe, but high doses may cause gastrointestinal discomfort.
Guar gum: It is also a safe food additive, but excessive intake may cause digestive problems such as bloating.
Pectin: Generally considered safe, but may cause allergic reactions in individual cases.
Hydroxypropyl methylcellulose: As a pharmaceutical excipient and food additive, HPMC has good safety, but its dosage should comply with relevant regulations.

Carboxymethyl cellulose shows its unique advantages in comparison with other thickeners, including good water solubility, versatility and a wide range of applications. Although other thickeners may have advantages in specific areas, such as the shear thinning properties of xanthan gum and the gel properties of pectin, CMC still has an important market position due to its diverse application prospects and excellent safety. When selecting a thickener, it is necessary to comprehensively consider factors such as thickening performance, application environment and safety to achieve the best effect.