Surfactants can be classified based on their ionic properties, molecular structure, and application fields. The following are common classifications of surfactants:
Non ionic surfactants: The molecules of non ionic surfactants are not charged and typically consist of compounds containing hydroxyl, ether, ester groups, etc. These surfactants exhibit good surface activity under neutral or slightly acidic conditions, with low sensitivity to hard water and electrolytes. Common non ionic surfactants include fatty alcohol polyoxyethylene ether (such as polyethylene glycol alcohol ether), fatty alcohol polyoxyethylene ester (such as polysorbate), alcohol ether sulfate, etc.
Cationic surfactants: The molecules of cationic surfactants are positively charged. They are usually compounds containing amine groups, amine bases, or quaternary ammonium bases. Cationic surfactants exhibit good surface activity in acidic environments and can be sterilized to a certain extent. Common cationic surfactants include hexadecyltrimethylammonium salt, hexadecyldimethylbenzylammonium chloride, etc.
Anionic surfactants: The molecules of anionic surfactants carry negative charges. They are usually compounds containing hydrophobic groups and anionic groups with hydrophilic groups. Anionic surfactants exhibit good surface activity under alkaline or neutral conditions and are widely used in fields such as detergents and cleaning agents. Common anionic surfactants include sulfates (such as sodium dodecyl sulfate) and sulfonates (such as sodium hexadecyl sulfonate).
Zwitterionic surfactants: Zwitterionic surfactants have molecules that are both positively and negatively charged, and typically have longer hydrophilic chains. These surfactants exhibit good surface activity over a wide pH range and exhibit good temperature and hard water resistance. Common Zwitterionic surfactants include sarcosine surfactants, phosphatidylcholine, etc.
In addition to the above classification, there are two special types of surfactants:
Biosurfactants: Biosurfactants are natural interfacial active substances produced by microorganisms. They have low toxicity and biodegradability, and have advantages in environmental friendliness. Common biosurfactants include lipopeptides, glycolipids, steroids, lipopolysaccharides, etc.
Functional surfactants: Functional surfactants are special surfactants obtained through structural modification or functional addition. They have specific functions, such as anti-static, anti-corrosion, thickening, etc. Common functional surfactants include silane and polymer modified surfactants.
These different types of surfactants have a wide range of applications in industries, homes, and pharmaceuticals, which can meet various application needs.