The invention relates to a method for preparing polyarylethersulfone-polyalkylene oxide block copolymers (PPC) comprising the polycondensation of a reaction mixture (RG) comprising the components: (A1) at least one aromatic dihalogen compound, (B1) at least one aromatic dihydroxyl compound, (B2) at least one polyalkylene oxide having at least two hydroxyl groups, (C) at least one aprotic polar solvent and (D) at least one metal carbonate, where the reaction mixture (RG) does not comprise any substance which forms an azeotrope with water.