Non-Linear Continuum Mechanics of Microemulsions and Amphiphilic Monolayers

Microemulsions are objects of chemical physics with great theoretical and practical importance. They consist of curved monomolecular fluid films of amphiphiles in the nano range, which separate oil from water. One way of understanding the variety of shapes and phases is the application of the continuum mechanical theory of surfaces with bending stiffness. The present monograph gives a comprehensive treatment within the framework of full non-linearity. Incorporated are bending and stretching of the film, the monomeric solubility of the amphiphile within the bulk fluids, and the influence of the pressures in the cavities. While the experimentally confirmed three-phase coexistence of a microemulsion with an oil and a water excess cannot be explained on the basis of a linear bending elasticity approach, the nonlinear setting can predict this phenomenon. It is demonstrated that a state of prestress within the amphiphilic film on the microscopic level can give rise to a symmetry breaking of the mesoscopic bending energy function and thus allows the existence of an X point in the macroscopic phase map.