Starting from its concept, its core parameter can be derived: the critical micelle concentration (CMC), which is the minimum concentration at which surfactants begin to form micelles in large quantities; Hydrophilic-Lipophilic Balance (HLB), used to quantify the strength of their hydrophilicity and lipophilicity, directly guiding their applications; and for ionic surfactants, Krafft point and cloud point for nonionic types.
Regarding classification, the most commonly used and systematic method is to categorize based on the ionic type of the hydrophilic groups.
- Anionic surfactants: The earliest types to achieve industrial production include soap, LAS, AES, SDS, etc. The advantages are strong cleaning power and low cost, while the disadvantages include poor tolerance to hard water and relatively high irritation.
- Cationic surfactants: Primarily quaternary ammonium compounds. Their most notable characteristics are bactericidal and antistatic properties, making them commonly used in disinfectants and hair conditioners.
- Zwitterionic surfactants: Including betaine and amino acid types. Their greatest advantages are mildness, low irritation, and good compatibility with other surfactants, making them commonly used in infant products and low-irritation formulations.
- Nonionic surfactants: Such as Span, Tween, AEO, alkyl glycosides, among others. They do not ionize in water, exhibit high stability, are minimally affected by electrolytes, and have good compatibility. The drawback is that they may have a relatively low cloud point.
In terms of application scenarios, surfactants have permeated nearly every aspect of modern life, forming a vast industrial backdrop.
- Household Laundry:Laundry detergent, laundry liquid, and dishwashing liquid are among the largest consumers of surfactants.
- Personal Care:Shampoo, body wash, facial cleanser, toothpaste, skincare products, etc., have high requirements for mildness.
- Industrial and Public Facility Cleaning (I&I): Specialized cleaning agents for hotels, catering, food processing, hospitals, etc., emphasizing efficiency, low foam, and rinsability.
- Petroleum Industry: Used as a displacement agent to enhance crude oil recovery.
- Numerous industrial sectors such as textiles, papermaking, pesticides, coatings, plastics, and building materials: As an additive to improve processing flow and product performance.