Abstract: A copolymer is described which is prepared by reacting a polyphenylene having two terminal coupling groups X1 and X2 with a flexible chain component which has a flexible chain having two terminal coupling groups Y1 and Y2. A high modulus of elasticity, high media resistance, and cost-effective, large-scale production may be achieved in that the flexible chain has a chain length of less than or equal to 95 chain atoms, and each of coupling groups X1 and X2 reacts with one of coupling groups Y1 and Y2, forming a bond selected from the group composed of carboxylic acid amide, carboxylic acid ester, carboxylic acid imide, urethane, carbonate, urea, thiourea, sulfonic acid amide, sulfonic acid ester, imidazole, oxazole, thiazole, oxazoline, imidazoline, amine, ether, and thioether bonds.