Hydroxylated Linear Polyurethanes Derived from Sugar Alditols

A set of linear [ m , n ]‐type polyurethanes was synthesized by reaction of HDI or MDI with conveniently protected sugar alditols L ‐threitol (LTh), L ‐arabinitol (LAr) and xylitol (Xy). $\overline M _{\rm n}$ of the resulting polyurethanes ranged between 10 000 and 60 000 with polydispersities around 2. They were thermally stable, showing no decomposition up to temperatures near 300 °C. They all were amorphous polymers with T g highly dependent on the constitution of the diisocyanate, but scarcely dependent on the structure of the alditol. Hydrogenation of the LThBn‐HDI polyurethane yielded partially debenzylated products with T g values ranging between 20 and 30 °C. Fully benzylated polyurethanes showed high resistance to hydrolytic degradation, whereas polyurethane with free hydroxyl side groups degraded significantly in saline buffer at pH = 10 and 37 °C.