AbstractThis performance study deals with isoporous ultrafiltration membranes made through a combination of self-assembly of amphiphilic block copolymers and the non-solvent induced phase separation process (SNIPS). Ten different polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) diblock copolymers were used to prepare membranes with pore sizes increasing with the molecular weight of the polymers. The pore diameters of the membranes vary from 17 to 86 nm. Pure water permeances were studied with respect to pore sizes, P4VP content, thickness of the membranes and flux recovery after protein adsorption. Suitable working conditions were identified and rejection of poly(ethylene glycol) (PEG) molecules with molecular weights between 100 and 1000 kDa were carried out. The characteristics of PS-b-P4VP diblock copolymer membranes were compared with a commercially available polyethersulfone ultrafiltration membrane.