The heterogeneity in molecular composition of segmented copolymers has been evidenced by studies on structures of different scales . It was proposed that in addition to microphase separation between hard and soft segments

the macrophase separation between segmented molecules of different composition or average segment length should be considered first in discussing the morphology and properties of segmented copolymers. The characterization and control of compositional heterogeneity become problems of importance for these polymers.