Anionic surfactants are the workhorse ingredients of most washing detergents. They are compounds such as sodium alkyl sulphate and are made up of molecules that have opposite charges at diff erent points (polar molecules). Water is also made of polar molecules and, when mixed with washing detergent, the hydrophilic (water-loving) part of the surfactant molecule attracts to the water molecule, while the hydrophobic (waterhating) part of the molecule adheres to the dirt and grease in your clothes. This makes the dirt and grime more soluble in the water, allowing for easier removal from your clothing. Another cleaning eff ect surfactants have is to lower the surface tension of water. Surface tension is created by these polar molecules pulling on one another due to their charge. This accounts for how pond skaters walk on water and why beads of water hang on grass. By lowering surface tension, the water can become more ‘wet’ and permeate clothes better.
