Amphoteric surfactants are well-established as extremely mild. They’re used as primary surfactants in mild formulations. When combined with anionic surfactants, they can reduce irritancy potential.
Amphoteric surfactants may contain two charged groups of different sign. Whereas the positive charge is almost always ammonium, the source of the negative charge may vary (carboxylate, sulphate, sulphonate).
1. Betaines or Betaine Amphoterics
More often used in Europe, betaines are better cleansers, produce more foam and viscosity response than glycinates and propionates (which are more often used in the US). Betaines can improve the quality of foam, making it creamier and finer. Usually used as a secondary surfactant.
Amphoacetate surfactants are extremely mild surfactants used in mild, tear-free shampoos and sensitive skin cleansers. They have a low-irritation profile and irritation-mollifying properties. Amphoacetates/diacetates are excellent foamers, even in hard water, and play exceptionally well with other surfactants.
3. Amine Oxides
Amine oxides are excellent foamers and combined with anionics, they boost foam and improve the structure of the foam. In cosmetics and shampoo, they likely act as non-ionics due to the pH being near neutral, but can become weakly cationic under acidic conditions. Most are used as primary/secondary emulsifiers in a formula and they’re known to play well with quaternary emulsions, even enhancing their preservative action.
4. N-Alkyl Amino acids
N-Alkyl amino acids or diacid amphoterics are compatible with other surfactants, electrolytes and hard water. They show good emulsifying, foaming and wetting properties.
5. Alkyl/Dialkyl Ethylenediamines & derivatives
Similar to betaines, these are compatible with other surfactants and tolerate hard water and electrolytes. Mild on the skin, but show poor to moderate emulsifying abilities.
The global surfactants market is expected to reach USD 46.20 billion by 2022, according to a new report by Grand View Research, Inc. Growth of personal care industry particularly in Asia Pacific, Latin America and Middle East is expected to remain a key driving factor for the global market. Amphoteric surfactants are expected to witness the highest growth of 6.0% from 2015 to 2022. – Source