Non-ionic emulsifiers are a type of surfactant that does not ionize in an aqueous solution. Their molecules contain hydrophilic groups such as polyoxyethylene groups, polyols and their fatty acid esters, as well as lipophilic long-chain alkyl groups or alkylphenyl groups. It achieves emulsification by forming a protective film at the oil-water interface to reduce the interfacial tension, and it has good stability under different acid-base conditions. Common examples include polyoxyethylene fatty alcohol ethers, the Span series and the Tween series. It is widely used in industries such as cosmetics, food, pesticides, coatings and inks, which can make products have a fine and stable texture, improve the taste, and enhance the performance, etc. This kind of emulsifier has advantages such as good emulsifying performance, good compatibility with other surfactants, and insensitivity to electrolytes. However, it also has disadvantages such as relatively high cost and sometimes the emulsifying ability is not as strong as that of anionic emulsifiers.

The molecular structure of non-ionic emulsifiers contains long-chain hydrophobic alkyl chains and hydrophilic carboxyl groups or ether bonds, having both lipophilic and hydrophilic functions. The advantages are that they are not affected by hard water, have good chemical stability to electrolytes, etc., and can be applied in a relatively wide pH range. The obtained emulsions have good electrolyte stability and freeze-thaw stability. The disadvantage is that when non-ionic emulsifiers are used alone, the latex particles are prone to agglomeration, resulting in unstable emulsions.