A series of new graft copolymers was synthesized by a "grafting to" approach, in the course of which the polymer backbone was build up first by a chain extension reaction of polyether or polycaprolactone diols with bis-N-acyl lactams. During the first reaction step, benzoxazinone groups were introduced into the backbone which served as grafting sites for monoamino-terminated polyamide 12 or polystyrene. Chain extension and grafting could be performed successively and with high selectivity in the melt at 180-220 degrees C.The morphology and the thermo-mechanical behavior of the graft copolymers were strongly influenced by the type of the grafted side chains. Polymers with polyamide grafts exhibited a two phase morphology with a spherulitic superstructure in the micrometer scale. The tensile behavior of these polymers was characterized by a certain elastic component.In contrast, the phase morphology of a polystyrene grafted polymer was much finer. A strong influence on the glass transitions revealed improved compatibility between the components. Pronounced strain hardening was observed during the tensile test of polystyrene grafted samples. (C) 2015 Elsevier Ltd. All rights reserved.