ABSTRACT
Since the early 1990’s, gemini surfactants have been a wellspring for colloid scientists [1-5]. Although known before that time [6,7], publications by Zana and Menger focused attention on the multimeric molecules having the schematic form as shown in Figure 29.1 [8-10]. Conventional single-head group/single-chain surfactants are well known to associate into aggregates via selfassembly processes, whereas the gemini surfactant contains two or more individual surfactant units that are covalently associated. These new molecules have provided new challenges and opportunities for researchers inclined to physical, theoretical, or synthetic aspects of surfactants. In many cases, the properties of gemini surfactants are rather ordinary in comparison to their monomeric cousins. In some cases, however, unusual and potentially useful solution phenomena have been observed, where certain geminis prove to be a lot more than the sum of their parts. As a result, gemini surfactants remain promising candidates for commercial production in areas ranging from cosmetic formulation components to gene transfection agents. The quest to discover new geminis has led to a wide range of surfactant structures requiring varying degrees of synthetic sophistication. With the aim of highlighting the rich structural variety that has developed over the past 15 years, this chapter surveys routes to produce gemini surfactants, the different classes that have been reported in publications and patents, and some of the commercially produced geminis.
