The synthesis and characterization of bisester-oligoamides segments with varying segment length that can be used in segmented block copolymers were studied. The bisester-oligoamides segments were made form diamines and terephthalate or isophthalate esters. The diamines used were p-xylylene diamine, m-xylylene diamine and hexamethylene diamine. The esters used are dimethyl terephthalate, diphenyl terephthalate, dimethyl isophthalate and diphenyl isophthalate. Uniform bisester-diamide, bisester-(tetra-ami des) and bisester(hexa-amide) segments were synthesized in steps and characterized by H-1 NMR, MALDI-TOF and DSC. The uniformity of these segments was studied by MALDI-TOF. With the uniform amide segments and polypropylene oxide segments, block copolymers were prepared by high temperature melt polymerization. The amide segment length distribution, which is susceptible to randomization was studied. The analysis of the amide segment distribution after hydrolysis of the ester-linkage groups was by MALDI-TOF. The amide segments were found to have the same narrow distribution as the starting bisester-oligoamide, which strongly supports the fact that randomization of the amide segments during melt polymerization does not take place. The uniformity of the amide segments is, therefore, preserved during high temperature melt polymerization. (c) 2005 Elsevier Ltd. All rights reserved.