A review. This feature article provides a comprehensive overview on the development of polymeric membranes having advanced or novel functions in the various membrane sepn. processes for liq. and gaseous mixts. (gas sepn., reverse osmosis, pervaporation, nanofiltration, ultrafiltration, microfiltration) and in other important applications of membranes such as biomaterials, catalysis (including fuel cell systems) or lab-on-chip technologies.