Tuning the demixing of colloid-polymer systems through the dispersing solvent

We report measurements on fluid-fluid phase separation in a colloid-polymer mixture by means of confocal scanning laser microscopy and we show that we can access the various coarsening regimes by tuning the properties of the solvent. By increasing the viscosity of the solvent we are able to access the diffusive hydrodynamic regime of spinodal decomposition. By matching the density of the solvent and colloids we are able to grow structures to large length scales before they are destroyed by buoyancy forces. Tuning the solvent's density furthermore gives control over which phase flows up and down, illustrating the flexibility of this particular system.