Unusual Surfactants

Wormlike micelle (WLM) formation was first reported in cationic surfactants with the addition of electrolytes. Other categories of surfactants (anionic, zwitterionic, non-ionic, etc.) have since been reported to form WLMs, but more recently a number of 'unusual' amphiphiles, which depart from these traditional categories, have also been shown to self-assemble into elongated aggregates. This chapter reviews various classes of WLM-forming surfactants that are 'unusual' either because of the nature of their chemical constituents (e.g. of biological origin) or their configuration (e.g. gemini). The chapter is divided into five sections and covers surfactants of biological origin (which includes amphiphilic peptides, nucleolipids, lipopolysaccharides and saponins); dimeric (gemini) and trimeric surfactants; ionic liquids; fluorosurfactants and surfactants with ultra-long chains.