Self-Assembly of Gemini Surfactants

The self-assembly of molecules into nano-structured materials is a fascinating process because small changes in intermolecular interactions can have a large impact on the final mesoscopic structures. An interesting goal is directed self-assembly where the chemical nature of the molecules drives the assembly into specific nanostructures. Gemini surfactants are composed of two single-tailed surfactants that are connected by a linker. They form a variety of lyotropic liquid crystalline phases depending on the concentration of surfactant, chemical structure of the molecules, and nature of counterions. Using computer simulation we show that both non-electrostatic and electrostatic interactions play an important role in the self-assembly of these systems. We obtain physical insight into the odd-even effect, where the phase behavior depends on whether the linker has an odd or even number of carbon atoms, and the effect of the counterions. We also investigate the structure and dynamics of the Frank-Kasper sigma phase that has been recently discovered in these systems.