Phase Transitions of Hard Spheres Plus Depletants Basics

Phase Transitions of Hard Spheres Plus Depletants Basics 

In this chapter we discuss the basics of the phase behaviour of hard spheres plus depletants. Phase transitions are the result of physical properties of a collection of particles depending on many-body interactions. In Chap. 2 we focused on two-body interactions. As we shall see, depletion elfects are commonly not pair-wise additive. Therefore, the prediction of phase transitions of particles with depletion interaction is not straightforward. As a starting point a description is required for the thermodynamic properties of the pure colloidal dispersion. Here the colloid-atom analogy, recognized by Einstein and exploited by Perrin in his classical experiments, is very useful. Subsequently, we explain the basics of the free volume theory for the phase behaviour of colloids -I- depletants. In this chapter we treat only simplest type of depletant, the penetrable hard sphere. 

The colloid-atom analogy can also be applied to interacting systems. The direct interaction potentials between atoms then have to be replaced by the potential of mean force between the dispersed colloidal particles. In the calculation of the 

Lekkerkerker and R. Tuinier, Colloids and the Depletion Interaction, Lecture Notes in Physics, 833, DOI 10.1007/978-94-007-1223-2 3, 

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