Hydroxyethyl cellulose, also called HEC, is a chemical compound derived from cellulose with a series of chemical and physical, non-ionic, soluble in hot or cold water.

The name describes the structure of the molecule:

• Hydroxyethyl. This indicates the presence of hydroxyethyl groups in the molecular structure. These groups consist of an ethyl group (-CH₂-CH₃) bonded to a hydroxyl group (-OH), imparting hydrophilic properties to the molecule.
• cellulose. This indicates that the molecule is derived from cellulose, a natural polymer composed of chains of glucose. Hydroxyethylcellulose is a derivative of cellulose that is often used as a thickener and stabilizer in cosmetic and pharmaceutical products.

The function of this compound is to act as a thickener and stabilizer in cosmetic and pharmaceutical formulations. Hydroxyethylcellulose is water-soluble and can increase the viscosity of an aqueous solution, improving its ability to form gels or stable suspensions. It is used in a wide range of products, including creams, lotions, shampoos, and eye lubricants.

Chemical Industrial Synthesis Process

The production of hydroxyethylcellulose (HEC) involves several steps designed to chemically modify cellulose, creating a water-soluble polymer widely used as a thickener, binder, and stabilizer in various industrial applications, including cosmetics, pharmaceuticals, and construction materials. 

• Cellulose selection. Raw cellulose, typically derived from cotton fibers or wood pulp, is selected as the base material.
• Cleaning and preparation. The cellulose is purified and prepared to ensure it is free from impurities before the chemical reaction.
• Alkylation. The cellulose is treated with ethylene oxide to introduce hydroxyethyl groups into the cellulose molecular structure. This step is conducted under controlled temperature and pH conditions.
• Neutralization. The modified cellulose is neutralized to stop the chemical reaction.
• Purification. The product is purified to remove any chemical and physical impurities.
• Drying. HEC is dried to reduce moisture content and convert it into a powdery or granular form.
• Packaging. Finally, HEC is packaged in bags or drums for distribution to various industrial sectors.

What it is used for and where

Cosmetics - INCI Functions

Binder agent. Ingredient that is used in cosmetic, food and pharmaceutical products as an anti-caking agent with the function of making the product in which it is incorporated silky, compact and homogenous. The binder, either natural such as mucilage, gums and starches or chemical, may be in the form of a powder or liquid.

Emulsion stabiliser. Emulsions are thermodynamically unstable. Emulsion stabilisers improve the formation and stability of single and double emulsions. as well as their shelf-life. It should be noted that in the structure-function relationship, the molar mass of the ingredient used plays an important role.

Film-forming agent. It produces, upon application, a very thin continuous film with an optimal balance of cohesion, adhesion and stickiness on skin, hair or nails to counteract or limit damage from external phenomena such as chemicals, UV rays and pollution.

Light stabilizer. It prevents light from degrading light-sensitive components and slows down degradation reactions that have already begun. The mechanism is, in a way, similar to antioxidants and the effectiveness depends on the.complexity of the formulation and the density of the product.

Viscosity control agent. It controls and adapts, Increasing or decreasing, viscosity to the required level for optimal chemical and physical stability of the product and dosage in gels, suspensions, emulsions, solutions. 

HEC comes in the form of white / yellowish powder.

HEC is used in many fields as a thickener, protector fluid, stabilizer, water release regulator.

• Paints. Polymeric emulsifier.
• Building. Thickener for cement and mortar .
• Cosmetics. Thickener and stabilizer.
• Ceramic. As a humidity regulator.
• Oil extraction. Fluid control.
• Medicines. Regulator of drug release (1) (2)

Molecular Formula    [C₆H₇O₂ (OH)₃-x OCH (OH) CH₃ x]

Molecular Weight    806.9 g/mol

CAS  9004-62-0

Bibliografia_________________________________________________________________________

(1) Chen YC, Ho HO, Liu DZ, Siow WS, Sheu MT. Swelling/floating capability and drug release characterizations of gastroretentive drug delivery system based on a combination of hydroxyethyl cellulose and sodium carboxymethyl cellulose. PLoS One. 2015 Jan 24;10(1):e0116914. doi: 10.1371/journal.pone.0116914. 

Abstract. The aim of this study was to characterize the swelling and floating behaviors of gastroretentive drug delivery system (GRDDS) composed of hydroxyethyl cellulose (HEC) and sodium carboxymethyl cellulose (NaCMC) and to optimize HEC/NaCMC GRDDS to incorporate three model drugs with different solubilities (metformin, ciprofloxacin, and esomeprazole). Various ratios of NaCMC to HEC were formulated, and their swelling and floating behaviors were characterized. Influences of media containing various NaCl concentrations on the swelling and floating behaviors and drug solubility were also characterized. Finally, release profiles of the three model drugs from GRDDS formulation (F1-4) and formulation (F1-1) were examined. Results demonstrated when the GRDDS tablets were tested in simulated gastric solution, the degree of swelling at 6 h was decreased for each formulation that contained NaCMC in comparison to those in de-ionized water (DIW). Of note, floating duration was enhanced when in simulated gastric solution compared to DIW. Further, the hydration of tablets was found to be retarded as the NaCl concentration in the medium increased resulting in smaller gel layers and swelling sizes. Dissolution profiles of the three model drugs in media containing various concentrations of NaCl showed that the addition of NaCl to the media affected the solubility of the drugs, and also their gelling behaviors, resulting in different mechanisms for controlling a drug's release. The release mechanism of the freely water-soluble drug, metformin, was mainly diffusion-controlled, while those of the water-soluble drug, ciprofloxacin, and the slightly water-soluble drug, esomeprazole, were mainly anomalous diffusion. Overall results showed that the developed GRDDS composed of HEC 250HHX and NaCMC of 450 cps possessed proper swelling extents and desired floating periods with sustained-release characteristics.

(2) Chen YC, Ho HO, Chiu CC, Sheu MT. Development and characterization of a gastroretentive dosage form composed of chitosan and hydroxyethyl cellulose for alendronate. Drug Des Devel Ther. 2013 Dec 27;8:67-78. doi: 10.2147/DDDT.S52791. 

Abstract. In this study, alendronate, the most commonly used biphosphonate for treating osteoporosis, was formulated as gastroretentive dosage form (GRDF) tablets to enhance its oral bioavailability. GRDF tablets were characterized with the effects of different molecular weights (MWs) of chitosan (CS) and hydroxyethyl cellulose (HEC) at various ratios on swelling, floating, and physical integrity. The CS component was formed using various acids: acetic, lactic, malic, succinic, and citric, and a high viscosity grade of HEC was selected. The results demonstrated that the swelling ratios of the formulations comprising high MW CS were lower than those of low or medium MW CS when salts were formed with any countering acids except for acetic acid. The decreasing ranking of the swelling rates was: CS-citrate > CS-malate > CS-lactate > CS-succinate > CS-acetate. A negative correlation was found between the pKa of the respective countering acid and the swelling rate. The swelling rate was promoted if an acidic salt of CS with a lower water content was incorporated, while it became slower when tablet hardness was higher or the compression force to form tablets was increased. Although HEC did not contribute to swelling or floating, it played a role in maintaining structural integrity. A prolonged dissolution profile of alendronate GRDF tablets developed in this study was observed.