Intermolecular and Surface Forces, 3rd Edition

Chapter 16 Steric (Polymer-Mediated) and Thermal Fluctuation Forces

16.1 Diffuse Interfaces in Liquids

So far, the particle-solution interface has been assumed to be smooth and rigid, possessing a sharp, well-defined boundary. There are many instances where this is not the case, where interfaces are spatially diffuse, and where the forces between them depend on how their diffuse boundaries overlap. By a diffuse surface or interface we do not mean that it is simply “rough,” but rather that it has thermally mobile surface groups—that is, that it is dynamically rough, not statically rough. There are two common types of such diffuse interfaces.

First, there is the interface that is inherently mobile or fluid-like, as occurs at liquid-liquid, liquid-vapor, ...