Nonionic surfactant

Nonionic surfactants are a class of surfactants that do not ionize after the molecules are dissolved in water. Before the Second World War, they were first developed by IG Germany. The trade names were Igepol, Leonil and Emulphor. According to its hydrophilic group, it is mainly divided into two categories: polyoxyethylene type and polyol type. 1 Polyoxyethylene type: The formula is RO(CH2CH2O)nH, which is prepared by reacting a compound containing an active hydrogen atom with ethylene oxide. Active hydrogen-containing compounds commonly used in the industry are fatty alcohols, alkyl phenols, fatty acids, fatty amines, fatty amides, polyhydric alcohols, fatty acid esters, fats and oils, sorbitol, and the like. Commercially available nonionic surfactants have the most ethylene oxide adducts of fatty alcohols and alkyl phenols. Polyoxyethylene surfactants are mostly soluble in water and have a wide range of applications. They are used in many industrial sectors as detergents, penetrants, leveling agents, and emulsifiers. 2 Polyol type: An ester or amide compound formed by the action of a compound containing a plurality of hydroxyl groups and a fatty acid. Polyol type nonionic surfactants have high safety and are less irritating to the skin. Therefore, they are used as an oil and softener for fibers, and as an emulsifier and dispersant in the food industry, the pharmaceutical industry and the cosmetics industry. The nonionic surfactant has high stability, is not easily affected by acid and alkali and strong electrolyte, and has good compatibility with anionic or cationic surfactants or amphoteric surfactants, and can be used in combination. The nonionic surfactant is not in an ionic state in the solution, so it has high stability, is not easily affected by strong electrolyte inorganic salts, and is not easily affected by acids and alkalis; it has good compatibility with other types of surfactants. It has good solubility in water and organic solvents (depending on the structure). Although such surfactants are not ionized in water, they have hydrophilic groups (such as oxyethylene-CH2CH2O-, ether-O-, hydroxy-OH or amide-CONH2, etc.) and oleophilic groups (such as hydrocarbon groups). R). The hydrophilic group and the lipophilic group can interact with the inorganic filler and the polymer binder, respectively, to strengthen the relationship between the two, thereby enhancing the compatibility between the two, and the flexible carbon between the dipolar groups. The chain acts as a plasticizing lubricant, imparting toughness and fluidity to the system, reducing the viscosity of the system and improving the processing properties of the composite. The aqueous solution of the nonionic surfactant has poor foaming power and the foam is also unstable. This is due to the fact that the nonionic surfactant has a large surface area per molecule and no charge at the interface of the foam. The chain length and relative molecular mass distribution of the polyoxyethylene, the chain length and branching of the lipophilic group, and the presence of the polyoxyethylene-polyoxypropylene block copolymer have a large influence on the foam of the nonionic surfactant. Surface activity is due to the polar and non-polar portions of the molecular structure. Such active agents can also be classified into ester types (such as polyoxyethylene fatty acid esters, sorbitan fatty acid esters), ether types (such as polyoxyethylene alkyl alcohol ethers, polyoxyethylene alkyl phenol ethers), amines. Types (such as polyoxyethylene fatty amine), amide type (such as polyoxyethylene alkyl amide) and mixed type (such as sorbitan fatty acid ester ethoxylate). In oil recovery, it is mainly used for foaming, emulsifying, anti-wax, corrosion inhibition, slow speed, oil well stimulation, water well injection, and oil recovery.