Nonionic surfactant

What is a nonionic surfactant?

A nonionic surfactant is a surfactant with a water-attracting head group that does not ionize in water. Instead of a charge, the head relies on polar groups, such as chains of ethylene oxide units or sugar groups, that bond with water.

Common types

• Alcohol ethoxylates, made by ethoxylation of fatty alcohols, the largest group.
• Alkyl polyglucosides, made from sugars and fatty alcohols.
• Sorbitan esters and polysorbates, common emulsifiers.
• Block copolymers of ethylene oxide and propylene oxide, often used as low-foam surfactants.
• Alkylphenol ethoxylates, once common but now restricted in some markets, including the European Union, because of environmental concerns.

Many glycolipid biosurfactants, whose head groups are sugars, behave largely like nonionic surfactants.

Properties and uses

• Hard-water tolerance. With no charge to bind calcium and magnesium, nonionics perform well in hard water.
• Low critical micelle concentration, so they are efficient at low doses.
• Compatibility with anionic, cationic and amphoteric surfactants.
• Tunable balance. The size of the head group can be adjusted to set the hydrophilic-lipophilic balance, a system originally developed for nonionic surfactants.
• Temperature sensitivity. Many become less water-soluble as temperature rises and separate at their cloud point.

Nonionic surfactants are used in laundry and hard-surface cleaners, agricultural spray adjuvants, emulsifiers, paints and industrial processes.

Frequently asked questions