Polymers modified with terminal acid groups and the preparation and use of these polymers

Homopolymers, copolymers or block copolymers obtained from vinylaromatics and/or conjugated dienes and functionally modified at chain ends via amide groups with terminal acid groups or salts thereof, and hydrogenation products of these polymers, which contain salts of functional groups of the formula I, II, III, IV or V I II III IV V wherein N is nitrogen, R1 is alkyl or aryl, R3 is a 2-membered to 20-membered bridge in which at least the members adjacent to the nitrogen atoms consist of -C(R6, R7) radicals, where R6 and R7 are each hydrogen, alkyl, cycloalkyl or aryl, and the more remote members are not only -C(R6, R7) radicals but may furthermore be ether or N-alkyl- or N-arylimino groups, R2 is a divalent organic radical, R4, R5, R8 and R9 are each alkyl or aryl or together form a cyclic bridge, and X is COOH or SO3H or their salts or complexes and a process for preparing the polymers and copolymers. The polymers and copolymers are used as toughening agents to modify polyurethanes, as a component of hot melt adhesives or as a lubricating oil component.