Methylcellulose (MC) and hydroxypropyl methylcellulose (HPMC) are two common cellulose derivatives that have some important differences in chemical structure and application areas. Here is a detailed comparison of them:

1. Chemical structure differences
Methylcellulose (MC):
Methylcellulose is a cellulose derivative made by introducing methyl (–CH?) groups into natural cellulose molecules. Some hydroxyl groups (–OH) in the cellulose molecule are replaced by methyl groups (–OCH?) to form methylcellulose. Usually the degree of methylation of methylcellulose is about 1.5 to 2.5 methyl groups.

Hydroxypropyl methylcellulose (HPMC):
Hydroxypropyl methylcellulose is a cellulose derivative that further introduces hydroxypropyl (–C?H?OH) groups on the basis of methylcellulose. The introduction of hydroxypropyl groups makes HPMC have better solubility and wider functionality. Its chemical structure contains two substituents, methyl and hydroxypropyl.

2. Differences in solubility
Methylcellulose (MC) has strong water solubility, especially in warm water, it can form a colloidal solution. Its solubility depends on the degree of methylation. The higher the degree of methylation, the better the water solubility.

Hydroxypropyl methylcellulose (HPMC) has better water solubility than methylcellulose. Because of the introduction of hydroxypropyl groups, HPMC can also dissolve well in cold water. Compared with methylcellulose, HPMC has a wider solubility, especially it can dissolve quickly at low temperatures.

3. Differences in physical properties
Methylcellulose (MC) is usually a colorless to white powder or granules, and the solution is viscous, with good emulsification, thickening and gelling properties. In some solutions, methylcellulose can form a relatively firm gel, but “gel rupture” occurs when heated.

Hydroxypropyl methylcellulose (HPMC) has a higher solution viscosity and better thermal stability. HPMC solutions are usually stable over a wider pH range and do not lose their gelling properties when heated like MC, so it is widely used in heat-sensitive products.

4. Application fields
Due to their unique solubility and physical properties, methylcellulose and hydroxypropyl methylcellulose are widely used in different fields:

Methylcellulose (MC):
As a thickener, emulsifier and stabilizer, it is widely used in the food industry, cosmetics and pharmaceuticals.
In building materials, MC is often used in cement, gypsum, tile adhesive and other products as a water retaining agent and thickener.
It is also used as an additive for coatings and inks.

Hydroxypropyl methylcellulose (HPMC):
As a thickener, emulsifier and stabilizer, HPMC is widely used in the pharmaceutical industry, especially in drug sustained-release preparations.
In the construction industry, HPMC is used in wall coatings, dry mortar, tile adhesive and other products to provide better adhesion and water resistance.
In the food industry, HPMC is often used as a thickener, stabilizer, emulsifier, etc.
In cosmetics, HPMC can be used as a humectant, gel former, etc.

5. Stability and heat resistance
Methylcellulose (MC) is sensitive to high temperatures. Especially when heated, the MC solution may gel and break, resulting in unstable solution. It is more soluble in hot water, but less soluble in cold water.

Compared with MC, hydroxypropyl methylcellulose (HPMC) has better thermal stability and wider pH adaptability, and can remain stable at higher temperatures, so it is widely used in products in high temperature environments.

6. Price and market
Due to the complex manufacturing process and high cost of HPMC, it is usually more expensive than methylcellulose. In some applications with lower requirements, methylcellulose may be a more cost-effective choice, while HPMC is more common in areas requiring higher performance, such as pharmaceuticals and high-performance building materials.

Although both methylcellulose (MC) and hydroxypropyl methylcellulose (HPMC) are derived from natural cellulose and have similar uses in many fields, their chemical structures, solubility, physical properties and application fields are different. HPMC is widely used in many fields (such as pharmaceuticals, construction and cosmetics industries) due to its better solubility and thermal stability, while MC is more used in some cost-sensitive applications.