Bilayer in a Liquid Self-Supported Film

The drainage of vertical soap films formed from nonionic surfactant solutions of pentaethylene glycol monododecyl ether (C12E5) was studied using Fourier transform infrared spectroscopy. At relatively low surfactant concentrations in the bulk solution (but above the critical micelle concentration), a transient surfactant bilayer was observed within these soap films. The expulsion of water and of a surfactant bilayer from the film was followed as a function of time. The bilayer found within the film displayed a much higher degree of molecular order than the two outer monolayers of the soap film. This study can serve as a model for similar studies on biomembranes.