Hypromellose, also known as hydroxypropyl methylcellulose (HPMC), is a synthetic polymer derived from cellulose. It is widely used in the pharmaceutical, food and cosmetic industries as a thickener, emulsifier and binder. HPMC is a non-toxic and biodegradable substance, making it a safe and environmentally friendly choice.

1. Water solubility

HPMC is soluble in water and forms a clear or slightly opalescent solution. The solubility of HPMC depends on its viscosity grade, molecular weight and degree of substitution. Higher viscosity and molecular weight grades are less soluble than lower grades. The degree of substitution determines the number of hydroxypropyl and methyl groups attached to the HPMC cellulose backbone. The higher the degree of substitution, the lower the water solubility.

2. Chemical reactivity

HPMC is chemically stable and does not react with most organic and inorganic chemicals. It is resistant to alkalis, weak acids and most organic solvents. However, HPMC reacts with strong acids and oxidizing agents, leading to its degradation and loss of performance. Therefore, it is recommended to avoid exposing HPMC to strong acids or oxidizing agents.

3. Film-forming properties

HPMC has excellent film-forming properties and is suitable for tablet coating, sustained release coating and encapsulation. The film formed by HPMC is flexible, transparent and smooth. The film also prevents the degradation of the active ingredient in the tablet or capsule.

4. Thermal gelation

Depending on its viscosity grade, HPMC undergoes thermal gelation when heated in water above a certain temperature. The gelation temperature ranges from 50°C to 90°C. The gel formed by HPMC is reversible, meaning it can be melted back to a liquid state by cooling. This property makes HPMC suitable for use in controlled-release formulations, since the drug can be released at a specific temperature.

5. Rheological properties

HPMC exhibits pseudoplastic behavior, meaning that its viscosity decreases with increasing shear rate. This property makes HPMC suitable for use as a thickener and stabilizer in food and cosmetic formulations. HPMC is also used as a suspending agent due to its thixotropic behavior, which means that its viscosity decreases under continuous shear stress.

HPMC is a versatile and safe substance with excellent chemical properties. Its water solubility, chemical stability, film-forming properties, thermogelling and rheological properties make it a popular choice in various industries. HPMC is also biodegradable and environmentally friendly, making it a sustainable choice.