Résumé
Phase separation of concentrated homopolymer solutions is both of fundamental interest (the large difference in viscosity/elasticity of the two phases can lead to unusual behaviors) and of practical importance (novel porous structures can be made by this process). I will first review how 2D phase-field simulations (Fig.1) reveal the influence of the mobility dependance with concentration for capturing features of phase separation like growth laws. On the experimental side I will examine various water-soluble polymers and show how anomalous phase diagrams seem to be closely connected to unusual features of arrested-like phase separation as evidenced by light scattering and confocal microscopy. Thin films of these polymer solutions were used for making membranes (Fig. 2), avoiding the use of organic solvents. The case of homo-polyelectrolytes is also of great interest since the theory is still controversial, as I will briefly recall. First results will be presented about phase separation upon changes in salt concentration, polymer concentration and temperature for a polyelectrolyte whose structure is also promising for membranes.