Effect of polyelectrolyte complex layers on the separation properties and the fouling behavior of surface and bulk modified membranes

The consecutive alternating polyelectrolyte adsorption was found to be a versatile tool for the preparation of membranes with controlled surface charge properties and hydrophilicity as demonstrated by ζ-potential measurements. Dense membranes, used in pervaporation, for example, showed an improved water selectivity after the formation of a PEL complex layer system. The permeate flux decreased with increasing selectivity and increasing layer number. It is possible to control the properties of pervaporation membranes by the number of adsorbed polyelectrolyte layers. The adsorption of only two polyelectrolyte layers onto a PAAc-grafted microfiltration membrane surface resulted in a reduced protein adsorption in the case of repulsive electrostatic interactions between the membrane surface and the feed components (e.g proteins). Higher protein retention was simultaneously observed. From these results a reduced fouling of PEL complex layer membranes was deduced when the membrane surface and the feed components are equally charged. These results could easily be achieved with membranes having a low degree of grafting (< 1 wt.-% PAAc). © WILEY-VCH Verlag GmbH, 2000.