Studies on thermoplastic polyurethanes based on new diphenylethane-derivative diols. I. Synthesis and characterization of nonsegmented polyurethanes from HDI and MDI

New aliphatic-aromatic alpha,omega-diols containing sulfur in aliphatic chain: 4,4'-(ethane-1,2-diyl)bis(benzenethioethanol) [EBTE], 4,4'-(ethane-1,2-diyl)bis(benzenethiopropanol) [EBTP], 4,4'-(ethane-1,2-diyl)bis(benzenethiohexanol) [EBTH], 4,4'-(ethane-1,2-diyl)bis(benzenetbiodecanol) [EBTD], and 4,4'-(ethane-1,2-diyl)bis(benzenethioundecanol) [EBTU] were prepared by the condensation reaction of 4,4'-(ethane-1,2-diyl)bis(benzenetbiol) with suitable halogen alcohols in aqueous sodium hydroxide solution. Thermoplastic nonsegmented polyurethanes containing sulfide linkages were synthesized from these diols, and hexane-1,6-diyl diisocyanate (HDI) or 4,4'-methylenediphenyl diisocyanate (MDI) by solution and melt polymerization. The reaction was carried out at 1: 1 or 1.05:1 molar ratios of isocyanate and hydroxy groups in the presence of dibutyltin dilaurate as a catalyst. The structures of the diols were determined by using elemental analysis, FTIR and H-1 NMR spectroscopy, and X-ray diffraction analysis. Thermal characteristics of the diols were determined by using differential scanning calorimetry (DSC). The polymers were studied to describe their structures and physicochemical, thermal (by DSC and thermogravimetric analysis) and tensile properties as well as Shore A/D hardness. All the polyurethanes possessed partially crystalline structures. Their melting temperatures were in the range of 94-179 degrees C (HDI) and 105-207 degrees C (MDI). The MDI-based polyurethanes showed higher tensile strengths, up to similar to 50 MPa. (c) 2006 Elsevier Ltd. All rights reserved.