Abstract
A method based on statistical thermodynamics has been used to describe concentration distributions of neutral and charged molecules in the vicinity of liquid-liquid or polymer membrane-liquid interfaces. The model is outlined and various applications are shown. One of these is a study of the transition region at the interface of two immiscible liquids. The results show that this transition is not sharp. The width of the interfacial region (where the concentration varies gradually) depends on the mutual solubility of the two liquids and on the size of the molecules. In another application the potential drop across the interfacial region has been calculated as a function of composition of the bulk phases. This type of calculation allowed the numerical simulation of the potentiometric behavior of a recently developed ion-selective electrode which employs negatively charged ion carrier.
