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The electrochemical behaviour of polyelectrolyte complex (PELC) membranes, prepared by simultaneous interfacial reaction between aqueous solutions of Na-cellulose sulphate (CS) on the one side and different polycations as well as cationic macroions on the other side, was investigated. Tangential streaming potential and concentration potential measurements were carried out in order to obtain a complete information on the nature and density of their effective surface charges. In the case of PELC membranes obtained from CS and polycations, their weak ion exchange properties are confirmed. On the other hand, in the case of PELC membranes obtained from CS and cationic surfactants, the results of tangential streaming potential measurements lead to a reinterpretation of earlier observations based on concentration potential measurements: Their properties are governed by specific sorption of anions from surrounding solutions. For the case of membrane systems obtained by laminating both types of PELC membranes one over the other, the characterization of gradients with respect to fixed charge density and/or morphology is demonstrated.

The ability of poly(2,6-dimethyl-1,4-phenylene oxide) membranes to separate water-ethanol mixtures by pervaporation was examined. Asymmetric membranes were prepared from solutions containing chloroform as a solvent and 1-butanol as a nonsolvent by the phase-inversion process. Homogeneous, dense membranes were prepared from chloroform solutions by evaporation. Nonporous membranes (membranes precipitated from solutions with a low amount of the nonsolvent or prepared by evaporation) were preferentially permeable to water. Microporous membranes (precipitated from solutions with a high amount of the nonsolvent) were preferentially permeable to ethanol, provided the membrane is not wetted by the feed solution. Die Eignung von Membranen aus Poly(2,6-dimethyl-1,4-phenylenoxid) fur die Trennung von Wasser-Ethanol-Gemischen mittels Pervaporation wurde untersucht. Asymmetrische Membranen entstanden durch Phaseninversion, wobei Chloroform als Losungsmittel und 1-Butanol als Nichtloser zur Anwendung kamen. Homogene, dichte Membranen wurden aus Losungen des Polymeren in Chloroform durch Abdunstung des Losungsmittels erhalten. Nichtporose Membranen, die bevorzugt permeabel fur Wasser sind, entstanden entweder durch Abdunstung oder durch Fallung aus Losungen mit geringem Nichtloseranteil. Mikroporose, aus Losungen mit hohem Nichtloseranteil hergestellte Membranen lassen bevorzugt Ethanol permeieren, vorausgesetzt, das die Feedlosung die Membran nicht benetzt.