Caption:Cross-sectional views of structures formed by detergents in water. Detergents can form monolayers at the air-water interface. They can also form micelles, aggregates of detergent molecules in which the hydrocarbon "tails" (yellow) associate away from water and the polar "head" groups (blue) are hydrated.
Notes：These structures are formed from detergent because of its linear structure. Phospholipids form bilayers or vessicles (small, spherical systems of bilayers) due to size restrictions of the "tail" groups. The "head" group hydration is similar to that of the hydration of other ions, such as chloride.