A surfactant is an organic chemical containing a hydrophobic, or water repellent, head and a hydrophilic tail, meaning one end of the compound is attracted to water, and therefore dissolvable in water. A non-ionic surfactant contains a head that is polar instead of charged.
The hydrophobic part of a surfactant generally contains a carbohydrate group that is composed of oxygen, hydrogen and carbon. The carbohydrate group on a non-ionic surfactant can be straight, branched, aromatic or cyclic, and also typically contains a long carbon chain. Van der Waals forces hold the molecules together, meaning they are non-polar and do not interact with water, which is polar.
The hydrophilic part classifies a surfactant into the separate groups of an-ionic, non-ionic, cat-ionic or amphoteric. In a non-ionic surfactant, the hydrophilic part typically contains an alcohol functional group or a bonded oxygen-hydrogen pair, also known as a hydroxyl. Due to uneven sharing of electrons between the hydrogen and the oxygen in the alcohol group, the molecule is polar and therefore attracted to water.
Common examples of non-ionic surfactants include polyethylene ethoxylates, polyoxyethylene glycol alkyl ethers and molecules containing fatty alcohol polyglycosides. Non-ionic surfactants are used in dishwashing and clothes detergents as a cleaning agent because the hyrophobic part breaks down grease and dirt, while the hydrophilic part attaches to water and washes away. They also prevent dirt from redepositing on clothing and dishes.