Zwitterionic surfactant

An amphoteric surfactant refers to a surfactant having both an anionic and a cationic hydrophilic group. In its structure, ions having opposite properties are simultaneously present, and a cation or an anion can be formed depending on external conditions (such as a change in pH). Practically speaking, the cationic moiety generally used is an amine salt or a quaternary ammonium salt type hydrophilic group, and the anionic portion is a carboxylate, a sulfonate or a phosphate type hydrophilic group, particularly an amino group and a carboxyl group in the same molecule. An amino acid type amphoteric surfactant, or a betaine type amphoteric surfactant comprising an intramolecular salt of a quaternary ammonium group and a carboxyl group. There are two types of amphoteric surfactants, one of which is sensitive to pH and the other is not sensitive in all pH ranges. The aqueous solution of the former has different degrees of dissociation due to different pH, and the anionic surface activity is alkaline. The nature of the agent is acidic when it is cationic, and it is neutral when it is nonionic surfactant. The equilibrium point of the cationic and anionic forms is called the isoelectric point, and the amino acid type amphoteric surfactant forms a precipitate at the isoelectric point. In contrast, the betaine type amphoteric surfactant has better solubility at the isoelectric point. Others such as hydroxyimidazoline type and N-alkyl betaine type are cationic in acidity. Another example is a sulfobetaine and a betaine amphoteric surfactant used in shampoos which are anionic at all pH values. Lecithin in egg yolk [1] is a phospholipid amphoteric surfactant and is the only ionic surfactant that can be used in the food industry. [1] It is basically insoluble in water and has excellent oil emulsification properties. In general, amphoteric surfactants are low in toxicity, antibacterial, excellent in hard water resistance, and have good compatibility with various surfactants. Therefore, it can be used as a foaming agent, a fiber detergent, a bactericide, etc. which are highly safe. For example, alkyl (diaminoethyl) glycine and di(alkylaminoethyl)glycine are amino acid type amphoteric surfactants which can be used as fungicides, and quaternized fatty acid amide glycine, which has mild properties and is almost non-irritating. Can be used in baby shampoos. Lauryl imidazolium betaine is a foaming agent for shampoos. Cocoamidopropyl betaine is an amphoteric surfactant that can be used in mild shampoos and skin cleansers. In general, amphoteric surfactants are rarely used alone, and most of them are used in combination with fatty alcohol sulfates to improve solubility, reduce irritation, increase viscosity, and increase foam stability. Amphoteric surfactants can also be used as antistatic agents for synthetic fibers, metal rust inhibitors, and the like. Because of the high cost, its use is limited. Amphoteric surfactants are rapidly developing varieties in recent years due to their low toxicity during use and low irritation to skin and eyes, and have good biodegradability, hard water resistance, emulsifying properties, dispersibility, Wettability, foaming, antistatic properties, and compatibility with all other types of surfactants, so the use of daily chemicals, textile industry, food, pharmaceuticals, dyes, pigments, etc. is expanding. It can be used as a fabric finishing aid, dyeing auxiliary, dispersing agent and dry cleaning agent. Although the price is still high, due to some of the above advantages, the application in some occasions is sufficient to compensate for the high price defects.