Polyurethanes with PTMO soft segments and toluene diisocyanate diamide as urethane segment were studied. The toluene diisocyanate diamide urethane segment was monodisperse in length. The soft segment length was changed by extending PTMO with TDI units to a soft segment length varying from 2 250 to 6 500 g · mol−1. Studied were the structure, the morphology, the thermal and thermal mechanical behavior, the elastic behavior, and the tensile properties. The monodisperse diisocyanate diamide urethane segments had a high crystallinity and the crystallites showed a curved nano-ribbon morphology. Extending the PTMO units with TDI groups increased Tg and Tm of PTMO slightly, and the elastic properties at room temperature were not affected.