MEMBRANES BASED ON BLENDING SOLUTIONS .1. MORPHOLOGY

The morphology of membranes based on blending solutions of a non-ionic polymer and a polyelectrolyte is studied as a function of composition and cation nature hold by the polyelectrolyte. Materials based on poly(vinylalcohol) (PVA) or poly(acrylonitrile) (PAN) blended with sodium poly(styrene sulfonate) (PSSNa) or its acidic form (PSSA) are examined by optical or electronic microscopy. The PAN-PSSNa and PAN-PSSA blends showed no miscibility whatever their composition in each phase. The detection of retrodiffused electrons allowed us to determine the composition in each phase. In the case of PAN-PSSA, an inversion phase phenomena appeared at about 33 wt% PAN. For the PVA-PSSNa and PVA-PSSA mixtures, phase separation was observed only at certain compositions. We concluded then that the polymers are only partly miscible. The influence of the polymer nature and cation of the polyelectrolyte on the phase separation phenomena are discussed.