ampholitic surfactant otherwise zwitterionic surfactant (rus. сурфактант, амфотерный otherwise амфотерное ПАВ; амфолитное ПАВ) — surfactant that can be a donor or an acceptor of the proton depending on the pH of the solution.

Description

Typically, an ampholitic surfactant comprises of one or more basic and acid groups, and can also contain a non-ionic polyglycol group. Depending on the pH, it can have the properties of cation or anion-active surfactants. At some pH, called the isoelectric point, the ampholitic surfactant exists in the form of bipolar ions, or zwitterions. They are neutral molecules containing both positive and negative ion sites. A cationic group can be a primary, secondary or tertiary ammonium group, a pyridine or imidazoline residue. Anionic groups are carboxylates, sulfonates, sulfoethers or phosphate groups.

Alkylbetaine RCH [N+(CH3)3] COO- can be an example of an ampholitic surfactant. Some natural polymers can be referred to as ampholitic surfactants: proteins and polynucleotides.

Authors

  • Eremin Vadim V.
  • Streletskiy Alexey V.

Sources

  1. Surface-active substances // Chemical encyclopedia (in Russian). V. 3. — Moscow: The Great Soviet Encyclopedia, 1992. P. 587–588.
  2. Laurier S. L. Dictionary of Nanotechnology, Colloid and Interface Science. — Wiley, 2008. — 290 p.

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