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

Abstract

New thermoplastic nonsegmented thiopolyurethanes were synthesized from the new low-melting aliphatic-aromatic thiodiols bis[4-(2-hydroxyethyl)thiomethylphenyl]methane, bis[4-(3-hydroxypropyl)thiomethylphenyl]methane, and bis[4-(6-hydroxyhexyl)thiomethylphenyl]methane and hexamethylene diisocyanate both by melt and solution polyaddition with dibutyltin dilaurate as a catalyst. All the thiodiols were prepared with high yields by the condensation reaction of bis(4-mercaptomethylphenyl)methane with 2-chloroethanol, 3-chloro-1-propanol, or 6-chloro-1-hexanol. The hard-segment-type polyurethanes obtained were plastic materials with partially crystalline structures. Polymerization in solution produced products with higher molecular weights (ηred = 0.97–1.24 dL/g) than polymerization in melt (ηred = 0.44–1.05 dL/g). The structures of all the polyurethanes were determined with elemental analysis, Fourier transform infrared, and X-ray diffraction analysis. Thermal properties of the polymers obtained in solution were examined by differential scanning calorimetry and thermogravimetric analysis. Shore A/D hardness 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 of 27.8–30.0 MPa at an elongation of 17.4–25.1%. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1767–1773, 2000