Structures Built by Amphiphiles and Frustrated Fluid Films

Interfaces between two non miscible liquids, such as water and oil, can be stabilized by amphiphilic molecules, such as soaps, detergents or lipids. The interfacial films formed by these molecules are known to build structures of an extraordinary polymorphism : ordered liquid crystals and "swollen" structures, disordered micellar solutions and microemulsions, liposomes and vesicles. We describe these structures, particularly the liquid crystalline ones, and propose a geometrical approach, which leads to consider them as structures of defects and is the basis of the crystallography of bi-dimensional objects necessary for their analysis.