The segregation on crystallization of polyester-polyether segmented copolymer in bulk has been observed

copolymer molecules segregate and form crystals of different melting point located near 140℃ and 160℃. Fraction of different melting point can be separated by thin layer chromatography. Eesults show that molecules of the higher melting point fraction have larger hard segment length and lower hard segment content

in contrast

molecules of the fraction of lower melting point have shorter hard segment length but more hard senment content. The heterogeneity in composition of the copolymer is supposed to be resulted rom the poor compatibility between the components of the polycondensation system.