Microemulsion ME is an oil phase separated in the form of spherical droplets in water, with particle sizes ranging from 10-100 nm. It is a transparent liquid that can automatically synthesize without any external energy.

Producing a qualified appearance is crucial to the success of preparing microemulsions. Microemulsions should have a transparent or translucent homogeneous liquid appearance, with no visible suspended particles or sediment. The selection of surfactants directly impacts the appearance stability of the microemulsion.

Hydrophilic-lipophilic balance (HLB) of non-ionic surfactants is sensitive to humidity. Whether the surfactant considers the change in temperature is also a criterion for its quality; as temperature rises, hydrophilicity decreases, and the system becomes cloudy. A good surfactant should strictly regulate the size of non-polar and polar groups within the molecules, maintaining a constant HLB value to ensure product stability. A good surfactant should also be able to blend various ionic and non-ionic surfactants in appropriate proportions to expand the product's temperature adaptability.