What is HPMC (hydroxypropyl methylcellulose)?

Hydroxypropyl methylcellulose (HPMC) is a water-soluble polymer obtained by etherification modification of natural cellulose. Some of the hydroxyl groups in its molecular chain are replaced by methyl and hydroxypropyl groups, thus exhibiting excellent solubility, stability, and biocompatibility, and is widely used in pharmaceuticals, food, building materials, and cosmetics.

Structure and Properties

The physicochemical properties of HPMC mainly depend on the degree of substitution of methyl and hydroxypropyl groups. This compound has good water solubility, thickening properties, and film-forming ability, and exhibits good heat resistance and acid/alkali resistance. Its gelling properties have important application value in controlled drug release.

Preparation Process

HPMC is mainly prepared by the etherification reaction of cellulose with chloromethane and propylene oxide (or hydroxypropyl chloride) under alkaline conditions. By controlling the reaction temperature, time, and feed ratio, key indicators such as molecular weight and viscosity can be customized. The product is purified and dried to obtain the final product.

Main Applications

Pharmaceuticals: Used as an adhesive, gel matrix, and excipient in sustained-release formulations such as tablets, capsules, and topical gels.

Food Industry: Used as a thickener, stabilizer, and water-retaining agent in baked goods, sauces, and desserts to improve texture and shelf life.

Building Materials: Used as a water-retaining agent and thickener in mortars, tile adhesives, and coatings to improve workability and bonding strength.

Cosmetics: Used as an emulsifying stabilizer, film-forming agent, and thickener, commonly found in creams, lotions, and hair care products.

Advantages and Limitations

HPMC possesses good biocompatibility, is odorless, and chemically stable, making it suitable for various industrial applications. However, it may degrade under prolonged high temperatures, and its cost is higher than some traditional thickeners.

In summary, hydroxypropyl methylcellulose (HPMC), with its excellent performance, has become an indispensable functional raw material in many industries. With technological advancements, its modification and application scope are expected to expand further.