Preparation method and pervaparation performance of polyelectrolyte complex/PVA blend membranes for dehydration of isopropanol

Poly(diallyldimethylammonium chloride) (PDDA)/sodium polyacrylate (PAANa) polyelectrolyte complex (PEC) was fabricated by adding PDDA dilute aqueous solution dropwise into PAANa dilute aqueous solution with 0.007 M HCl. PEC/PVA(polyvinyl alcohol) blend liquids and their blend membranes were prepared by two blend methods of (a) PVA-solution/PEC-solution blending commonly used and (b) PVA-solid/PEC-solution blending proposed. Both blend liquids obtained were studied by viscometry and particle size analysis meter. Surface morphologies of PEC/PVA blend membranes cast from blend liquids were characterized by atomic force microscopy (AFM) and field emission scanning electron microscope (FESEM). Dynamic water contact angle and equilibrium swelling degree (ESD) of blend membranes in water–isopropanol feed were measured. Pervaporation (PV) dehydration of blend membranes for water–isopropanol feed was investigated. It was found that the structure and property of blend liquids, the surface property and ESD of blend membranes prepared by (b) are quite different from those prepared by (a). The stability and PV performance of PEC/PVA blend membranes prepared by (b) is much better than that prepared by (a). It is attributed to the preparation methods, which led to the difference in the interaction in blend liquids and the transition of fluid property and finally the change of the compatibility between PEC and PVA in blend membranes.