Track-etched poly(ethylene terephthalate) capillary pore membranes with a pore diameter of 690nm were functionalized via photo-initiated olivingo radical graft polymerization with block copolymers of acrylic acid and N-isopropylacrylamide. Preadsorbed xanthone was more efficient than benzophenone in order to achieve higher grafting efficiency and olivingo character, including the option to reinitiate a grafted homopolymer to obtain grafted diblock copolymers. Characterizations were mainly done with water flux and dextran diffusion experiments at temperatures below and above the lower critical solution temperature (32 degrees C) of poly(N-isopropylacrylamide) and pH values below and above the pKa value (4.5) of poly(acrylic acid). Block sequences and relative block lengths were identified to obtain stimuli-responsive membranes which have no measurable water flux and allow only low dextran diffusion rates at 25 degrees C and pH 7 (oclosed stateo), and which reversibly open their pores by either increase of temperature or decrease of pH, or by the combination of both stimuli.