Segmented polyurethanes (SPU) have been used as an important biomedical material

the biocompatibility of which will be strongly influenced by the surface properties of the polymer. ESCA has been used in the present study to characterize the surface morphology of SPU samples with different degree of phase segregation. Our experimental results show that (1) the ratio of O/N on polymer-air interface is greater than that in the bulk

i.e. more soft segment is found on the suface than in the bulk average; (2) the soft segment is more abundant on the surface for the samples with better phase segregation

and (3) the compositional variation of the samples with better phase segregation is higher than the samples with less phase segregation.