The introduction of formulations comprising blends of amphoteric and anionic surfactants is regarded as one of the most significant innovations in personal cleansing products over the past six decades.1–4 This can be attributed to the synergistic interaction of anionics and amphoterics, which enables formulators to simultaneously increase the viscosity and foaming ability of cleansers while dramatically decreasing irritation potential to the skin and eyes. “True” amphoterics are surfactants that can exist either in anionic, zwitterionic or cationic form (see Figure 1) depending upon the solution pH. Betaines, on the other hand, can only exist in cationic or zwitterionic forms due to the presence of a quaternary ammonium group, yet they are still frequently referred to as amphoterics.
Although their use has been far surpassed by the more cost-effective betaines, amphoterics still remain an important class of surfactants in personal care, home care and industrial applications due to their mildness and versatility. The present column features one of the oldest and most well-known members of the amphoteric family: sodium lauroamphoacetate (SLAA).
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