Weak flocculation and phase separation in particulate dispersions

4 Weak flocculation and phase separation in particulate dispersions 

As was demonstrated in the Section 6.3.2.3 breakdown of steric stabilisation can lead to weak, reversible flocculation. The main occurrences are summarised below  

For flocculation equilibrium, one may write the classical thermodynamic condition. 

One may also write down the classical Boltzmann relationship for the ratio of the concentrations of the particles in two energy states , that is, the dispersed and flocculated states, 

An aqueous, polymer particle system, which behaves similarly to the Silica-nCis/ cyclohexane system, in the sense that the van der Waals forces may be tuned by varying temperature, has recently been described by Rasmusson et al. (2004). The particles were poly(N-isopropylacrylamide) (PNIPAM) gel microparticles, which carried surface —SO groups from the initiator residues. 

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