Intermolecular interactions and phase equilibria in colloidal systems

Abstract

Colloidal systems often show a rich phase behaviour and the macroscopic properties of a particular system are strongly dependent on the phase characteristics. The study of phase equilibria is thus fundamental for understanding the basic features of colloidal systems. Another classical problem in colloidal science concerns the forces between particles, surfaces or aggregates, which are the result of complex interplay between many molecular degrees of freedom. Even though both the phase equilibrium and force problems have been extensively studied less attention has been given to the question how the forces between aggregates influence the phase behaviour. By way of examples it will be demonstrated how one from measured or calculated force-distance curves can deduce the phase behaviour. Conversely it will also be demonstrated how one can use observed phase behaviour to draw conclusions about surface forces. In addition the phase behaviour also can reveal an interesting interplay between long range and short range forces. By formulating a quantitative model that takes into account both the long range and short range interactions it is possible to obtain a rather detailed understanding of the phase behaviour of a particular system. In the presentation these general aspects will be discussed in relation to the molecular characteristics and phase behaviour of four types of systems. © 1988, Walter de Gruyter. All rights reserved.