Synthesis and properties of sulfur-containing linear polythioesters derived from bis(4,4'-mercaptophenyl)sulfide (MPS) and various acid dichlorides (AC) have been studied to evaluate the effect of the thioester group in comparison with corresponding linear polyesters. Polycondensations between MPS and azelaoyl chloride (AZC) chosen as a model reaction system were investigated under various conditions by solution polycondensation, to find optimal conditions to get high molecular weight and quantitative yield. The obtained polymer using chloroform as a solvent indicated the highest molecular weight, determined by gel permeation chromatography (GPC). Thus the polythioesters from MPS and AC were synthesized under the above-mentioned conditions. The thermal properties of polythioesters including the NIPS moiety were evaluated by thermogravimetry/differential thermal analysis (TG/DTA), and differential scanning calorimetry (DSC). Those indicated that the polythioesters including the MPS moiety were crystalline polymers with relatively high heat resistance. These polythioesters were found to show an odd-even effect with the glass transition temperature, melting point, and oxygen permeability based on the methylene numbers. The tensile strength and storage modulus decreased with the number of methylene units. (C) 2005 Wiley Periodicals, Inc.