Progress in the Synthesis of Zwitterionic Gemini Surfactants

Zwitterionic gemini surfactants have hydrophilic head groups consisting of two polar groups with different charges. Species synthesized to date can be classed as anionic-cationic, anionic-nonionic, and cationic-nonionic. These surfactants not only have a small repulsion between the hydrophilic head groups, but also have a more compact arrangement at the interface, which greatly reduces the surface and interfacial tensions. In addition, owing to the existence of zwitterions, they are endowed with a unique aggregation morphology and unique rheology in solution, so they has the potential for a number of applications. The present research situation and potential research directions of the synthesis methods of the three types of zwitterionic gemini surfactants are discussed in this paper.