Transparent sulfur-containing thermoplastic polyurethanes with polyether and polycarbonate soft segments

Abstract

New thermoplastic polyether- and polycarbonate-based segmented polyurethanes were synthesized by a catalyzed one-step melt polyaddition from diphenyl sulfide-derivative diol, i.e., 2,2′-[sulfanediylbis(benzene-1,4-diyloxy)]diethanol as a nonconventional chain extender, 1,1′-methanediylbis(4-isocyanatocyclohexane), and 40, 50, and 60 mol% poly(hexane-1,6-diyl carbonate) diol (PHCD) of overline{M}_{text{n}} = 8 60 ;{text{g}}/{text{mol}} or poly(oxytetramethylene) diol (PTMO) of overline{M}_{text{n}} = 1000 {text{g}}/{text{mol}} as soft segments. The structures and thermal properties of the polymers were examined by FTIR, elemental analysis, differential scanning calorimetry, thermogravimetry (TG), and TG-FTIR. Moreover, their Shore A/D hardness, tensile, physicochemical, adhesive, and optical properties were determined. The obtained colorless, transparent, amorphous materials exhibited elastomeric or plastic properties. The PTMO-based polymers showed lower glass-transition temperatures than those based on PHCD (from −29 to 5 °C vs. from 11 to 43 °C) as well as a higher degree of microphase separation. On the other hand, the polymers with the polycarbonate soft segments revealed better transparency (transmittance at 800 nm: 84–89% vs. 75–82%), higher tensile strength (up to 48.6 MPa vs. up to 28.3 MPa), and hardness in comparison with those with the polyether soft segments. The polymers decomposed in two (in helium) or three (in air) stages and possessed a relatively good thermal stability. Their temperatures of 1% mass loss were contained within the range of 255–274 °C. In inert atmosphere, the values shown by polymers from PTMO were higher than those from PHCD, whereas in oxidative atmosphere, the situation was reversed. The newly synthesized sulfur-containing polymers showed a higher refractive index and adhesive strength to copper than analogous polymers based on butane-1,4-diol as a chain extender.