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Two series of high-molar-mass thermoplastic poly(carbonate–urethane)s (PCURs) were synthesized from nonconventional sulfur-containing chain extenders, i.e., 2,2′-[sulfanediylbis(benzene-1,4-diyloxy)]diethanol (diol SE) and 2,2′-[methanediylbis(benzene-1,4-diylmethanediylsulfanediyl)]diethanol (diol ME), 1,1′-methanediylbis(4-isocyanatobenzene) and 30, 45 and 60 mol% aliphatic polycarbonate diol of M n = 2000 g mol−1 (Desmophen® C2200, Bayer) via a one-step melt polyaddition. The PCURs were investigated by FTIR, UV–Vis, atomic force microscopy, X-ray diffraction analysis, differential scanning calorimetry, thermogravimetry (TG) and TG-FTIR. Moreover, their Shore A/D hardness, tensile, adhesive and optical properties were determined. The obtained PCURs were transparent or opaque elastomers, possessing amorphous or partially crystalline structures. The polymers based on diol ME showed lower glass transition temperatures (−9 to (−8) vs. −7 to 20 °C) and better microphase separation. All the PCURs exhibited a relatively good thermal stability. Their temperature of 1 % mass loss was within the range of 284–292 °C with somewhat higher values shown by those obtained from diol ME. The PCURs decomposed in two (from diol ME) or three (from diol SE) stages, and for both types of polymers, the main decomposition occurred at the first stage. All the PCURs based on diol SE exhibited higher tensile strength (33.5–41.9 vs. 27.0–31.5 MPa), but smaller elongation at break (300–400 vs. 450–550 %) than polymers derived from diol ME. Somewhat better adhesive properties and a slightly higher refractive index were found for polymer based on diol ME with two sulfur atoms.

New thermoplastic polyurethane elastomers (TPUs) were obtained by a one-step melt polyaddition from 30, 45 and 60 mol% aliphatic polycarbonate diol of M n = 2000 g mol−1 (Desmophen® C2200, Bayer), 1,1′-methanediylbis(4-isocyanatocyclohexane) (HMDI) or 1,6-diisocyanatohexane (HDI) and 2,2′-[sulfanediylbis(benzene-1,4-diyloxy)]diethanol (acting as a chain extender). The TPUs were examined by FTIR, UV–Vis, atomic force microscopy, X-ray diffraction analysis, differential scanning calorimetry, thermogravimetry (TG) and TG–FTIR. Moreover, their Shore A/D hardness, tensile, adhesive and optical properties were determined. The obtained TPUs were transparent or opaque high molar mass materials, showing amorphous or partially crystalline structures. The HDI-based TPUs exhibited lower glass-transition temperatures than those based on HMDI (from −35 to −31 °C vs. from −20 to 1 °C) as well as a higher degree of microphase separation. The TPUs were stable up to 262–272 °C, taking into account the temperature of 1 % mass loss, with somewhat higher values shown by those from HDI. They decomposed in two stages. The main volatile products of the hard-segment decomposition were carbon dioxide, water and carbonyl sulfide, while aliphatic ethers, aldehydes and unsaturated alcohols, as well as carbon dioxide, originated from the soft-segment decomposition. The synthesized TPUs, with hardness in the range of 80–90°Sh A, possessed a good tensile strength (33.0–38.7 MPa), similar to that of the commercial biodurable medical grade TPU ChronoFlex® AL 80A (37.9 MPa), prepared from aliphatic polycarbonate diol, HMDI and butane-1,4-diol.