New linear polyurethanes derived from 4,4'-bis(6-hydroxyhexylthio)diphenyl ether and methylene bis(4-phenyl isocyanate) were synthesized by either melt or solution polymerization with a strictly equimolar ratio of the monomers. In the solution method, good results were obtained with the aprotic solvent N,N-dimethylformamide at an approximately 20 wt % concentration of the monomers, with dibutyltin dilaurate as a catalyst, the process being conducted at 90-100degreesC for 4 h. The basic physicochemical properties of the polymers were investigated with thermogravimetric analysis and differential scanning calorimetry. The molecular weight distribution was determined by gel permeation chromatography. Shore hardness and tensile test results were also examined. The structures of the resulting products were confirmed with elemental analysis, Fourier transform infrared, and X-ray diffractometry. The properties of the copolyurethanes, containing various amounts of poly(oxytetramethylene) diol (similar to1000) or polycaprolactone diol (similar to1250) and synthesized under the conditions for the nonsegmented polyurethanes, were also examined. (C) 2003 Wiley Periodicals, Inc.