Entropy and fluctuations of monolayers, membranes, and microemulsions

Conformational entropy of the interfaces in microemulsions and surfactant solutions has been predicted, under some circumstances, to have significant effect upon their thermodynamic behavior. Continuum theories have led to a consistent phenomenological description of the effects of undulations, but conclusive experimental evidence for or against the predicted effects remains elusive in all but the lamellar phase. Work on the bicontinuous phases has led to an increasing focus on the role of topology and Gaussian rigidity, and on the role of anharmonic (in curvature) contributions to the bending energy.