The difference between HPMC and MC

Hydroxypropyl Methylcellulose (HPMC) and Methylcellulose (MC) are both cellulose derivatives commonly used in a variety of industries, including pharmaceuticals, food, cosmetics, and construction. Despite their similarities, these two materials have distinct chemical properties and applications.

1. Chemical Structure

Both HPMC and MC are cellulose derivatives, but the key difference lies in the chemical groups that are attached to the cellulose backbone.

Methylcellulose (MC): This is formed by methylation of cellulose. In this process, methyl groups (-CH3) are attached to the hydroxyl groups of the cellulose molecules. The methylation degree typically varies between 20-30%, depending on the grade of MC, which influences its solubility and other properties.

Hydroxypropyl Methylcellulose (HPMC): KimaCell®HPMC is a more complex derivative. In addition to methylation, it also undergoes hydroxypropylation. Hydroxypropyl groups (-CH2CHOHCH3) are introduced to the cellulose molecule, along with methyl groups. The hydroxypropylation degree and methylation degree of HPMC can vary significantly, which gives rise to a variety of HPMC grades with different characteristics.

2. Solubility

Solubility is one of the most important factors when comparing MC and HPMC. The solubility of both these cellulose derivatives depends on the degree of substitution and the specific formulation of the material.

Methylcellulose (MC): MC is soluble in hot water but forms a gel upon cooling. This unique property of forming gels when heated and reverts to a liquid state upon cooling is one of the most significant characteristics of MC. It is insoluble in cold water, but soluble in hot water above a certain temperature threshold (50–70°C), and the gelation process is reversible.

Hydroxypropyl Methylcellulose (HPMC): HPMC, on the other hand, is soluble in both cold and hot water. This makes it more versatile compared to MC. The solubility of HPMC is influenced by the type of substitution (the ratio of methyl to hydroxypropyl groups) and the viscosity grade. Higher substitution degrees tend to make HPMC more soluble in water at lower temperatures.

3. Viscosity

Viscosity plays a crucial role in many applications, especially in the pharmaceutical and food industries.

Methylcellulose (MC): The viscosity of KimaCell®MC solutions is temperature-dependent. The viscosity increases when heated, and it exhibits the phenomenon of gelation. The degree of substitution also affects the viscosity, with higher substitution levels generally resulting in higher viscosity.

Hydroxypropyl Methylcellulose (HPMC): HPMC generally has a more consistent viscosity profile compared to MC. The viscosity of HPMC is also influenced by the degree of substitution, but it remains stable across a broader range of temperatures. Additionally, HPMC can be tailored to have various viscosities, from low to high, depending on the intended application.

4. Applications

Both MC and HPMC are used extensively in the pharmaceutical, food, and cosmetics industries, but the specific properties of each make them more suitable for certain applications.

Methylcellulose (MC):

Pharmaceuticals: MC is often used as a binder, disintegrant, and coating agent in tablet formulations due to its gelation properties. It is also used in controlled-release formulations.

Food Industry: MC is used as a food thickener, emulsifier, and stabilizer. Its gel-forming property is valuable in making products like ice cream, salad dressings, and bakery products.

Cosmetics: MC is used in cosmetics for its thickening, emulsifying, and stabilizing properties in products like lotions, shampoos, and creams.

Hydroxypropyl Methylcellulose (HPMC):

Pharmaceuticals: HPMC is widely used as a binder and controlled-release agent in tablet formulations. It is also used in ophthalmic solutions as a lubricant and in gel-based drug delivery systems.

Food Industry: HPMC is used in gluten-free baking, as it mimics the texture and elasticity of gluten in dough. It is also used as a stabilizer and emulsifier in various processed foods.

Construction: HPMC is used as an additive in cement, plaster, and tile adhesives. It improves workability, water retention, and adhesion.

5. Other Properties

Hygroscopicity: HPMC is generally more hygroscopic (water-attracting) than MC, which makes it useful in applications where moisture retention is required.

Thermal Stability: MC tends to exhibit better thermal stability due to its gelation property. HPMC, while stable in a wider temperature range, may not provide the same thermal gelation effect as MC.

6. Summary of Differences

While both HPMC and MC are cellulose derivatives with overlapping applications, their distinct chemical structures and properties make them more suitable for different uses. MC is particularly valuable in applications that benefit from its gelation property, while HPMC’s superior solubility and thermal stability make it more versatile across industries, including food processing and pharmaceuticals. Understanding these differences helps in selecting the appropriate material for specific applications.