Overview of amphoteric surfactants

This type of surfactant has both positive and negative charged groups in its molecular structure, and can exhibit the properties of cationic or anionic surfactants in media with different pH values.
1. Lecithin
Lecithin is a natural zwitterionic surfactant, mainly derived from soybeans and egg yolks. The composition of lecithin is very complex and is a mixture of various compounds. Because of its different sources and preparation processes, the proportions of each component will also be different, so the performance will also be different. Lecithin is very sensitive to heat and is easily hydrolyzed under the action of acidity, alkalinity and esterase. It is insoluble in water and soluble in organic solvents such as chloroform, diethyl ether and petroleum ether. It is the main excipient for the preparation of injectable emulsions and lipid particles.
2. Amino acid type and betaine type
Amino acids and betaine are synthetic amphoteric surfactants. The anionic part is mainly carboxylate, the cationic part is an amine salt, which is the amino acid type (R-NH2+-CH2CH2COO-), and the quaternary ammonium salt is betaine. Type: R-N+(CH3)2-COO-. Its characteristics are: it behaves like an anionic surfactant in alkaline aqueous solution and has good foaming and decontamination effects; it behaves like a cationic surfactant in acidic solution and has strong bactericidal ability and bactericidal effect. Stronger and less toxic than cationic surfactants.