I.Definition

The emulsion is a colloidal system with a particle size of 0.1~10μm formed by two insoluble liquids through the action of emulsifier. Secondary dispersion refers to a colloidal system formed by particles (or molecular groups) less than 1μm are dispersed into a continuous phase (such as water) under the action of a stabilizer. By definition, the formation of emulsions and secondary dispersions requires a certain stabilizer or emulsifier.

II. Stability

Both emulsions and secondary dispersions are stabilized by stabilizers or emulsifiers to keep droplets or particles stable, but their stabilization mechanisms are slightly different. Secondary dispersions are generally more stable because they have a smaller particle size, exhibit a larger surface area in a continuous phase, and generally require fewer stabilizers. The stability of the emulsion depends on the size and distribution of the droplets, and more emulsifiers are needed to maintain stability.

III. Application Fields

Due to their differences in stability and composition structure, emulsions and secondary dispersions are also different in the field of application. Emulsions are usually used in cosmetics, emulsions and coatings, while secondary dispersions are more commonly used in drug delivery, nanocrystal growth, dye transport and other fields.

IV. Summary

In summary, the difference between emulsions and secondary dispersions is mainly reflected in their definition, stability and application field. Although they are different in the formation mechanism and application scope, they are all colloidal particle systems, and they can play a very good performance and effect in applications.