Polyurethanes containing sulfur. II. New thermoplastic nonsegmented polyurethanes with diphenylmethane unit in their structure

New thermoplastic nonsegmented thiopolyurethanes were synthesized from the new low-melting aliphatic-aromatic thiodiols bis[4-(2-hydroxyethyl)thiometh ylphenyl] methane, bis[4-(3-hydroxypropyl)thiomethylphenyl] methane, and bi s [4-(6-hydroxghexyl)thiomethylphenyl] methane and hexamethylene diisocyana te both by melt and solution polyaddition with dibutyltin dilaurate as a ca talyst. All the thiodiols were prepared with high yields by the condensatio n reaction of bis(4-mercaptomethylphenyl)methane with 2-chloroethanol, 3-ch loro-1-propanol, or 6-chloro-1-hexanol. The hard-segment-type polyurethanes obtained were plastic materials with partially crystalline structures. Pol ymerization in solution produced products with higher molecular weights (et a(red) = 0.97-1.24 dL/g) than polymerization in melt (eta(red) = 0.44-1.05 dL/g). The structures of all the polyurethanes were determined with element al analysis, Fourier transform infrared, and X-ray diffraction analysis. Th ermal properties of the polymers obtained in solution were examined by diff erential scanning calorimetry and thermogravimetric analysis. Shore A/D har dness and tensile properties for all the polyurethanes were also determined . Of the two kinds, the polyurethanes obtained in solution possessed better tensile properties and showed yield stress (tensile strength) in a range o f 27.8-30.0 MPa at an elongation of 17.4-25.1%. (C) 2000 John Wiley & Sons, Inc.