the invention relates to a method for producing a polymer membrane with an isoporous , active separation layer , particularly an ultrafiltration membrane or nanofiltration membrane and to a polymer membrane produced or producible according to the invention . the method comprises the following steps : producing a casting solution having at least one solvent in which at least one amphiphilic block copolymer with at least two different polymer blocks and at least one carbohydrate are dissolved , spreading out the casting solution to form a film , allowing a part of the at least one solvent near the surface to evaporate during a waiting time , precipitating a membrane by immersing the film in a precipitation bath comprising at least one non - solvent for the block copolymer .