Polyurethanes with pendant hydroxy groups: polycondensation of D-mannitol-1,2 : 5,6-dicarbonate with diamines

The bis(ethylene carbonate) monomers 3,4-O-isopropylidene-D-mannitol-1,2:5,6-dicarbonate (2) and D-mannitol-1,2:5,6-dicarbonate (1) were prepared from D-mannitol in yields of 81 and 74%. respectively. These AA-type monomers were reacted with alpha, omega-diamines (H2N-(CH2)(x)-NH2; x = 2-10 and 12) as BB-type monomers in the sense of a polycondensation reaction. The molecular weights of the polyurethanes with pendant hydroxy groups obtained were determined by means of gel permeation chromatography in dimethylacetamide/LiCl and are in the range of 20 x 10(3) to 87 x 10(3) with polydispersity indices of ca. 1.6. The polyurethanes show primary and secondary hydroxy groups with a ratio of ca. 15 : 85. This is a consequence of the different direction of opening of the substituted ethylene carbonate ring which results in structurally isomeric repeating units. The polyurethanes obtained from 2 and diamines with two free hydroxy groups and two protected hydroxy groups in the repeating unit are semicrystalline materials with melting points between 160 and 190 degrees C and glass transition temperatures of 64 to 79 degrees C. The polyurethanes derived from I and diamines with four free hydroxy groups in the repeating unit show glass transition temperatures of 50 to 70 degrees C; no melting transition is observed before decomposition starts at ca. 200 degrees C. Polymer analogous esterification reactions were successfully performed with acyl chlorides; the properties of the acylated polyurethanes differ from those of the starting polymers and depend on the acyl chloride used.