The key difference between microemulsion and nanoemulsion is that microemulsions are thermodynamically stable, whereas nanoemulsions are thermodynamically unstable.
Microemulsion and nanoemulsion are two different types of emulsions. An emulsion is a fine dispersion of minute droplets of one liquid in another in which it is not soluble or miscible. We can describe an emulsion as a mixture of two liquids that are immiscible with each other. An emulsion is a type of colloid. We often tend to use the two terms emulsion and colloid interchangeably, but the term emulsion specifically explains the mixture of two liquids that form a colloid.
CONTENTS
1. Overview and Key Difference
2. What is Microemulsion
3. What is Nanoemulsion
4. Microemulsion vs Nanoemulsion in Tabular Form
5. Summary – Microemulsion vs Nanoemulsion
What is Microemulsion?
Microemulsion is a clear, stable isotropic liquid that contains a mixture of oils, water, and surfactant. It is a thermodynamically stable liquid often consisting of a cosurfactant. The aqueous phase of this microemulsion contains salts and other ingredients, whereas the oil phase of this microemulsion contains a complex mixture of various hydrocarbon compounds. In comparison to ordinary emulsions, these microemulsions are created upon the simple mixing of components. In other words, it does not require high shear conditions that are generally useful in the formation of ordinary emulsions. There are three major types of microemulsions: direct microemulsion, reversed microemulsion, and biocontinuous microemulsion.
Figure 01: Emulsion
Furthermore, in the presence of the aqueous and oil phases of the microemulsion, the surfactant molecules in the microemulsion tend to create a monolayer at the interface between the oil phase and water phase. The surfactant molecule has hydrophobic tails which are dissolved in the oil phase. It also has hydrophilic head groups dissolved in the aqueous phase.
There are several important applications of microemulsions, which include dry cleaning processes, floor polishing processes, as cleaners, as ingredients in personal care products, in pesticide formulations, as cutting oils, and as components in some drugs.
What is Nanoemulsion?
Nanoemulsion is also known as miniemulsion and is a special case of emulsion. This type of emulsion is created when shearing a mixture comprising of two immiscible liquid phases along with one or more surfactants and also a cosurfactant.
When preparing a nanoemulsion, we can use two general methods: high-energy methods and low-energy methods. The high-energy processes use the technique of exposure to a high-power ultrasound of the mixture. Or else, we can use a high-pressure homogenizer. When considering the low-energy miniemulsion production, we can first make a water-oil emulsion which is then transformed into an oil-in-water miniemulsion through the changing of either the composition of the mixture or the temperature of the mixture.
In contrast to microemulsions, nanoemulsions are thermodynamically unstable. However, they are kinetically stable. Thermodynamical instability arises due to the fact that oil and water are incompatible in nature; hence, the interface between these two phases is not favored. However, the presence of the surfactant and cosurfactant can suppress this fact. In addition to that, we can obtain stable droplets having dimensions between 50 to 500 nm due to the presence of surfactants.
What is the Difference Between Microemulsion and Nanoemulsion?
Microemulsion is a clear, stable isotropic liquid that contains a mixture of oils, water, and surfactant. It is a thermodynamically stable liquid often consisting of a cosurfactant. Nanoemulsion is also named miniemulsion and is a special case of emulsion. The key difference between microemulsion and nanoemulsion is that microemulsions are thermodynamically stable, whereas nanoemulsions are thermodynamically unstable.
The below infographic presents the differences between microemulsion and nanoemulsion in tabular form for side by side comparison.
Summary – Microemulsion vs Nanoemulsion
Microemulsion and nanoemulsion are two different types of emulsions. The key difference between microemulsion and nanoemulsion is that microemulsions are thermodynamically stable, whereas nanoemulsions are thermodynamically unstable.
Reference:
1. Jaiswal, Manjit, et al. “Nanoemulsion: An Advanced Mode of Drug Delivery System.” 3 Biotech, Springer Berlin Heidelberg, Apr. 2015.
Image Courtesy:
1. “Emulsion formation” By Cruithne9 – Own work (CC BY-SA 4.0) via Commons Wikimedia