Theory on the Collapse Pressure of Mixed Insoluble Monolayers with Miscible Components

Using the chemical potential of each component in the surface and the bulk phases an equation was deduced, which allows to predict the collapse pressure of a mixed insoluble monolayer with miscible components, from the collapse pressure of each component separately. It was shown that the collapse of a mixed monolayer, is completely analogue to the distillation or crystallisation from a mixture. The equation deduced previously by Crisp is only of limited value. The present theory allows to investigate interaction at the interface. The theory was illustrated by a few systems cholesterol/cholanic acid, disteraoyllecithin/cholesterol, desoxycholic acid/tripalmitin and soybean lecithin/oleic acid.