PHASE-SEPARATION IN COLLOIDAL SUSPENSIONS INDUCED BY A SOLVENT PHASE-TRANSITION

A colloidal suspension of macroparticles in a solvent is considered near a solvent first-order phase transition. The solvent phase transition is described by a Ginzburg-Landau model with a one-component order parameter which is coupled to the macroparticles coordinates. Wetting of the macroparticle surface by one of the two coexisting phases can induce phase separation of the colloidal particles. This phase separation is first explained by simple thermodynamic arguments and then confirmed by computer simulation of the Ginzburg-Landau model coupled to the macroparticles. Furthermore a topological diagnosis of the interface between the stable and metastable phase is given near phase separation and possible experimental consequences of the phase separation are discussed.