How does detergent break an oil film into separate droplets?

Detergents break an oil film into separate droplets through their unique molecular structure, which consists of both a hydrophobic (water-insoluble) part and a hydrophilic (water-soluble) part.1

When a detergent solution is applied to a soiled surface, the hydrophobic portion of the detergent molecules attaches itself to the oil or grease, while the hydrophilic portion remains oriented toward the surrounding water. This process displaces the oil film from the surface. As the detergent solution interacts with the oil, the film breaks up and separates into individual, stable droplets.1

These droplets are maintained in a highly dispersed condition by the detergent, which prevents them from coalescing or redepositing onto the cleaned surface. In many cases, these molecules form micelles—spherical aggregates where the hydrophobic chains sequester the grease in the interior, effectively suspending the oil in the water so it can be easily washed away. This action is further facilitated by mechanical agitation and temperature, which help disperse the soil into the wash water.12