The invention relates to a method for producing a diblock copolymer comprising the conversion of at least one aromatic polyester having a melting point in the range from 160 to 350 癈 and at least one polymer diol having a melting point of less than 100 癈 at a temperature greater than 200 癈 producing a mixture (G-a) and the conversion of the mixture (G-a) having at least one diisocyanate wherein the diisocyanate is used in a molar quantity of at least 0.9 based on the alcohol groups of the polymer diols. The invention further relates to diblock copolymers obtained or obtainable by such a method and to the use of such diblock copolymers for producing extruded injection moulded and pressed articles and foams cable sheaths hoses profiles drive belts fibres nonwovens foils molded parts plugs housings damping elements for the electrical industry automobile industry mechanical engineering 3D printing medicine and consumer goods.